:root {
  --bg: #04070f;
  --bg2: #0a1024;
  --glass: rgba(255, 255, 255, .05);
  --glass2: rgba(255, 255, 255, .08);
  --border: rgba(255, 255, 255, .10);
  --border2: rgba(255, 255, 255, .20);
  --input: rgba(255, 255, 255, .05);
  --text: #eaf0ff;
  --muted: #8fa0c8;
  --accent: #00d4ff;
  --violet: #7c3aed;
  --pink: #ff2ec4;
  --green: #2fe6a6;
  --red: #ff5d7a;
  --yellow: #ffcf4d;
  --grad: linear-gradient(120deg, #00d4ff, #7c3aed 55%, #ff2ec4);
  --shadow: 0 24px 70px rgba(0, 0, 0, .5);
  --glow: 0 0 26px rgba(0, 212, 255, .35);
  --codebg: #090d1c;
  --symbol: rgba(255, 255, 255, .45);
  --gridline: rgba(255, 255, 255, .035);
  --blob1: rgba(0, 212, 255, .30);
  --blob2: rgba(124, 58, 237, .36);
  --blob3: rgba(255, 46, 196, .24);
  --radius: 18px;
  --navy: #0b1226;
}

[data-theme="light"] {
  --bg: #eef3fb;
  --bg2: #e3ebf8;
  --glass: rgba(255, 255, 255, .68);
  --glass2: rgba(255, 255, 255, .9);
  --border: rgba(20, 40, 90, .12);
  --border2: rgba(20, 40, 90, .24);
  --input: #ffffff;
  --text: #101a38;
  --muted: #5a6a94;
  --shadow: 0 24px 60px rgba(30, 50, 120, .16);
  --symbol: rgba(40, 60, 120, .40);
  --gridline: rgba(20, 40, 90, .05);
  --blob1: rgba(0, 140, 255, .16);
  --blob2: rgba(124, 58, 237, .14);
  --blob3: rgba(255, 46, 196, .10);
  --navy: #ffffff;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box
}

html {
  scroll-behavior: smooth
}

body {
  font-family: 'Inter', system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  overflow-x: hidden;
  transition: background .4s, color .4s;
}

h1,
h2,
h3,
h4,
.logo {
  font-family: 'Space Grotesk', sans-serif
}

code,
pre,
.mono {
  font-family: 'JetBrains Mono', monospace
}

a {
  color: inherit;
  text-decoration: none
}

button {
  font-family: inherit;
  cursor: pointer;
  border: 0;
  background: none;
  color: inherit
}

input,
textarea,
select {
  font-family: inherit
}

::selection {
  background: rgba(0, 212, 255, .30)
}

::-webkit-scrollbar {
  width: 10px;
  height: 10px
}

::-webkit-scrollbar-track {
  background: transparent
}

::-webkit-scrollbar-thumb {
  background: linear-gradient(180deg, #1c2a55, #141d3d);
  border-radius: 99px
}

::-webkit-scrollbar-thumb:hover {
  background: #263565
}

/* ---------- Animated background ---------- */
.bg {
  position: fixed;
  inset: 0;
  z-index: -3;
  background:
    radial-gradient(1100px 750px at 85% -10%, rgba(124, 58, 237, .20), transparent 60%),
    radial-gradient(950px 700px at -10% 30%, rgba(0, 212, 255, .14), transparent 60%),
    radial-gradient(900px 600px at 50% 115%, rgba(255, 46, 196, .11), transparent 60%),
    var(--bg);
  transition: background .4s;
}

.bg-grid {
  position: fixed;
  inset: 0;
  z-index: -2;
  background-image: linear-gradient(var(--gridline) 1px, transparent 1px),
    linear-gradient(90deg, var(--gridline) 1px, transparent 1px);
  background-size: 44px 44px;
  -webkit-mask-image: radial-gradient(ellipse at 50% 0%, #000 25%, transparent 75%);
  mask-image: radial-gradient(ellipse at 50% 0%, #000 25%, transparent 75%);
}

.blob {
  position: fixed;
  border-radius: 50%;
  filter: blur(100px);
  z-index: -2;
  animation: blobMove 18s ease-in-out infinite alternate;
  pointer-events: none
}

.blob.b1 {
  width: 430px;
  height: 430px;
  background: var(--blob1);
  top: -130px;
  left: -110px
}

.blob.b2 {
  width: 390px;
  height: 390px;
  background: var(--blob2);
  top: 28%;
  right: -130px;
  animation-delay: -6s
}

.blob.b3 {
  width: 320px;
  height: 320px;
  background: var(--blob3);
  bottom: -120px;
  left: 32%;
  animation-delay: -12s
}

@keyframes blobMove {
  from {
    transform: translate(0, 0) scale(1)
  }

  to {
    transform: translate(70px, 50px) scale(1.18)
  }
}

.symbol {
  position: fixed;
  font-family: 'JetBrains Mono', monospace;
  color: var(--symbol);
  z-index: -2;
  font-weight: 700;
  animation: floatY 9s ease-in-out infinite;
  pointer-events: none;
  user-select: none;
  transition: color .4s
}

@keyframes floatY {

  0%,
  100% {
    transform: translateY(0) rotate(-4deg)
  }

  50% {
    transform: translateY(-28px) rotate(4deg)
  }
}

/* ---------- Navigation ---------- */
.nav {
  position: fixed;
  top: 14px;
  left: 0;
  right: 0;
  margin: 0 auto;
  width: min(1240px, calc(100% - 32px));
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 12px 20px;
  border-radius: 18px;
  background: var(--glass);
  border: 1px solid var(--border);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  box-shadow: var(--shadow);
  z-index: 60;
  transition: background .4s, border-color .4s, transform .25s;
  box-sizing: border-box;
  flex-wrap: nowrap;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 18px;
  white-space: nowrap;
  padding: 8px 10px;
  border-radius: 14px;
  transition: .25s;
  min-height: 44px;
  flex-shrink: 0;
}

.logo:hover {
  background: var(--glass2);
}

.logo-img {
  width: 34px;
  height: 34px;
  border-radius: 12px;
  object-fit: contain;
  background: rgba(255, 255, 255, .06);
  padding: 4px;
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, .08);
}

.logo-text {
  font-size: 17px;
  letter-spacing: .03em;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 1 1 auto;
  min-width: 0;
  justify-content: flex-start;
  margin: 0 14px;
  overflow-x: auto;
  scrollbar-width: none;
}

.nav-links::-webkit-scrollbar {
  display: none;
}

.nav-link {
  padding: 10px 12px;
  border-radius: 14px;
  font-size: 13.2px;
  font-weight: 600;
  color: var(--muted);
  white-space: nowrap;
  transition: color .22s ease, background .22s ease, transform .22s ease;
  position: relative;
  flex-shrink: 0;
}

.nav-link:hover {
  color: var(--text);
  background: rgba(255, 255, 255, .06);
  transform: translateY(-1px);
}

.nav-link.active {
  color: var(--text);
  background: rgba(0, 212, 255, .12);
}

.nav-link.active::after {
  content: "";
  position: absolute;
  left: 12px;
  right: 12px;
  bottom: 6px;
  height: 2px;
  border-radius: 2px;
  background: var(--grad);
}

.nav-right {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-left: 0;
  flex-shrink: 0;
}

.icon-btn {
  width: 44px;
  height: 44px;
  border-radius: 14px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 17px;
  background: var(--glass2);
  border: 1px solid var(--border);
  transition: border-color .25s ease, box-shadow .25s ease, transform .25s ease;
  padding: 0;
}

.icon-btn:hover {
  border-color: var(--accent);
  box-shadow: var(--glow);
  transform: translateY(-2px)
}

.user-chip {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 12px;
  border-radius: 999px;
  background: var(--glass2);
  border: 1px solid var(--border);
  transition: border-color .25s ease, box-shadow .25s ease, transform .25s ease;
  max-width: 220px;
}

.user-chip:hover {
  border-color: var(--accent);
  box-shadow: var(--glow);
  transform: translateY(-1px);
}

.user-chip .u-avatar {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: var(--grad);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  font-weight: 800;
  color: #fff;
  flex: none;
}

.user-chip .u-name {
  font-size: 13px;
  font-weight: 700;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.hamburger {
  display: none;
  width: 44px;
  height: 44px;
}

.mobile-menu {
  position: fixed;
  top: 76px;
  right: 16px;
  width: min(340px, calc(100% - 32px));
  background: var(--glass);
  border: 1px solid var(--border);
  backdrop-filter: blur(24px);
  border-radius: 18px;
  padding: 12px;
  z-index: 59;
  box-shadow: var(--shadow);
  transform: translateY(-14px);
  opacity: 0;
  pointer-events: none;
  transition: transform .3s ease, opacity .3s ease;
}

.mobile-menu.open {
  transform: none;
  opacity: 1;
  pointer-events: auto;
}

.mobile-menu .nav-link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 14px;
  font-size: 15px;
  border-radius: 14px;
  transition: background .25s ease;
}

.mobile-menu .nav-link.active {
  background: rgba(0, 212, 255, .10);
}

body.auth-mode .nav,
body.auth-mode .mobile-menu {
  display: none;
}

body.auth-mode #app {
  padding: 0
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 13px 28px;
  border-radius: 14px;
  font-weight: 700;
  font-size: 15px;
  color: #fff;
  background: linear-gradient(120deg, #00d4ff, #7c3aed 55%, #ff2ec4);
  background-size: 170% 170%;
  box-shadow: 0 8px 26px rgba(0, 212, 255, .28);
  transition: .3s;
  border: 0;
}

.btn:hover {
  transform: translateY(-2px);
  background-position: 100% 50%;
  box-shadow: 0 12px 34px rgba(124, 58, 237, .45)
}

.btn:active {
  transform: translateY(0) scale(.98)
}

.btn-block {
  width: 100%
}

.btn-lg {
  padding: 16px 36px;
  font-size: 16px;
  border-radius: 16px
}

.btn-sm {
  padding: 9px 18px;
  font-size: 13.5px;
  border-radius: 11px
}

.btn-ghost {
  background: var(--glass2);
  border: 1px solid var(--border2);
  color: var(--text);
  box-shadow: none
}

.pdf-viewer-card {
  border-radius: 22px;
  overflow: hidden;
  background: var(--glass);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: 16px;
  padding: 20px;
}

.pdf-viewer-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}

.pdf-viewer-header h3 {
  margin: 0;
  font-size: 20px;
}

.pdf-frame {
  width: 100%;
  min-height: 620px;
  background: rgba(0, 0, 0, .05);
  border-radius: 18px;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, .08);
}

.pdf-frame iframe {
  width: 100%;
  height: 100%;
  min-height: 560px;
  border: 0;
}

.card-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 16px;
}

@media (max-width:980px) {
  .pdf-viewer-card {
    padding: 18px;
  }

  .pdf-frame {
    min-height: 500px;
  }
}

@media (max-width:680px) {
  .pdf-viewer-card {
    padding: 16px;
  }

  .pdf-frame {
    min-height: 420px;
  }
}

.btn-ghost:hover {
  border-color: var(--accent);
  box-shadow: var(--glow)
}

.btn-green {
  background: linear-gradient(120deg, #12c98e, #2fe6a6);
  box-shadow: 0 8px 26px rgba(47, 230, 166, .25)
}

.btn-green:hover {
  box-shadow: 0 12px 34px rgba(47, 230, 166, .4)
}

.btn-danger {
  background: linear-gradient(120deg, #ff5d7a, #e0245e);
  box-shadow: 0 8px 26px rgba(255, 93, 122, .25)
}

.btn-danger:hover {
  box-shadow: 0 12px 34px rgba(255, 93, 122, .4)
}

.btn:disabled {
  opacity: .55;
  cursor: not-allowed;
  transform: none !important
}

.copy-btn {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 7px 14px;
  border-radius: 9px;
  font-size: 12.5px;
  font-weight: 700;
  background: rgba(0, 212, 255, .12);
  color: var(--accent);
  border: 1px solid rgba(0, 212, 255, .3);
  transition: .25s
}

.copy-btn:hover {
  background: rgba(0, 212, 255, .22);
  box-shadow: 0 0 16px rgba(0, 212, 255, .3)
}

.copy-btn.copied {
  background: rgba(47, 230, 166, .15);
  color: var(--green);
  border-color: rgba(47, 230, 166, .4)
}

/* ---------- Cards / glass / badges ---------- */
.glass {
  background: var(--glass);
  border: 1px solid var(--border);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-radius: var(--radius);
  transition: background .4s, border-color .4s
}

.card {
  padding: 26px;
  border-radius: var(--radius);
  background: var(--glass);
  border: 1px solid var(--border);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  transition: transform .3s, box-shadow .3s, border-color .3s
}

.card:hover {
  transform: translateY(-4px);
  border-color: var(--border2);
  box-shadow: var(--shadow)
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 12px;
  border-radius: 99px;
  font-size: 12px;
  font-weight: 700
}

.b-html {
  background: rgba(255, 122, 89, .13);
  color: #ff9d7a;
  border: 1px solid rgba(255, 122, 89, .35)
}

.b-css {
  background: rgba(0, 212, 255, .12);
  color: var(--accent);
  border: 1px solid rgba(0, 212, 255, .35)
}

.b-js {
  background: rgba(255, 207, 77, .12);
  color: var(--yellow);
  border: 1px solid rgba(255, 207, 77, .35)
}

.b-green {
  background: rgba(47, 230, 166, .12);
  color: var(--green);
  border: 1px solid rgba(47, 230, 166, .35)
}

.grad-text {
  background: var(--grad);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent
}

.muted {
  color: var(--muted)
}

.flex {
  display: flex;
  align-items: center
}

.between {
  display: flex;
  align-items: center;
  justify-content: space-between
}

.gap10 {
  gap: 10px
}

.gap14 {
  gap: 14px
}

.gap20 {
  gap: 20px
}

.mt10 {
  margin-top: 10px
}

.mt16 {
  margin-top: 16px
}

.mt24 {
  margin-top: 24px
}

.mt32 {
  margin-top: 32px
}

.section-title {
  font-size: 20px;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 11px;
  margin-bottom: 18px
}

.section-title::before {
  content: "";
  width: 5px;
  height: 22px;
  border-radius: 4px;
  background: var(--grad)
}

/* ---------- Layout ---------- */
#app {
  max-width: 1240px;
  margin: 0 auto;
  padding: 104px 20px 70px;
  min-height: 100vh
}

.page-head {
  margin-bottom: 30px;
  animation: fadeUp .5s ease both
}

.page-head h1 {
  font-size: clamp(26px, 4vw, 38px);
  font-weight: 700
}

.page-head p {
  color: var(--muted);
  margin-top: 8px;
  max-width: 640px;
  line-height: 1.65
}

.grid {
  display: grid;
  gap: 20px
}

.grid-2 {
  grid-template-columns: repeat(2, 1fr)
}

.grid-3 {
  grid-template-columns: repeat(3, 1fr)
}

.grid-4 {
  grid-template-columns: repeat(4, 1fr)
}

@keyframes fadeUp {
  from {
    opacity: 0;
    transform: translateY(22px)
  }

  to {
    opacity: 1;
    transform: none
  }
}

@keyframes pop {
  0% {
    transform: scale(.7);
    opacity: 0
  }

  100% {
    transform: scale(1);
    opacity: 1
  }
}

/* ---------- Auth pages (login / register) ---------- */
.auth-wrap {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 70px;
  padding: 40px 20px;
  animation: fadeUp .55s ease both
}

.auth-side {
  max-width: 520px;
  flex: 1 1 480px
}

.auth-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 22px;
  font-weight: 700;
  margin-bottom: 26px
}

.auth-side h1 {
  font-size: clamp(30px, 4.6vw, 48px);
  line-height: 1.14;
  font-weight: 700;
  margin-bottom: 18px
}

.auth-side .lead {
  color: var(--muted);
  font-size: 16.5px;
  line-height: 1.7;
  margin-bottom: 26px
}

.auth-points {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-bottom: 28px
}

.auth-points div {
  display: flex;
  gap: 9px;
  align-items: center;
  font-size: 14px;
  font-weight: 600;
  padding: 11px 14px;
  border-radius: 13px;
  background: var(--glass);
  border: 1px solid var(--border)
}

.auth-points span {
  color: var(--green);
  font-weight: 800
}

.auth-code {
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid var(--border);
  background: var(--codebg);
  box-shadow: var(--shadow);
  animation: floatY 8s ease-in-out infinite
}

.auth-code .code-head {
  display: flex;
  gap: 7px;
  padding: 12px 16px;
  background: rgba(255, 255, 255, .05);
  border-bottom: 1px solid rgba(255, 255, 255, .08)
}

.auth-code .dot {
  width: 11px;
  height: 11px;
  border-radius: 50%
}

.auth-code pre {
  padding: 18px;
  font-size: 13px;
  line-height: 1.75;
  color: #c8d6f5;
  overflow-x: auto
}

.auth-card {
  position: relative;
  width: min(440px, 100%);
  flex: none;
  padding: 38px 36px;
  border-radius: 24px;
  background: var(--glass);
  backdrop-filter: blur(26px);
  -webkit-backdrop-filter: blur(26px);
  border: 1px solid var(--border);
  box-shadow: var(--shadow), 0 0 90px rgba(124, 58, 237, .14);
  animation: pop .5s .12s ease both
}

.auth-card::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 24px;
  padding: 1.5px;
  background: var(--grad);
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
  opacity: .65
}

.auth-card h2 {
  font-size: 26px;
  margin-bottom: 6px
}

.auth-card .sub {
  color: var(--muted);
  font-size: 14px;
  margin-bottom: 26px
}

.field {
  position: relative;
  margin-bottom: 15px
}

.field .ic {
  position: absolute;
  left: 15px;
  top: 50%;
  transform: translateY(-50%);
  opacity: .55;
  font-size: 16px;
  pointer-events: none
}

.field input {
  width: 100%;
  padding: 14px 16px 14px 46px;
  border-radius: 13px;
  background: var(--input);
  border: 1px solid var(--border);
  color: var(--text);
  font-size: 15px;
  outline: none;
  transition: .25s
}

.field input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(0, 212, 255, .15);
  background: var(--glass2)
}

.field input::placeholder {
  color: var(--muted);
  opacity: .7
}

.name-hint {
  font-size: 12px;
  color: var(--muted);
  margin: -6px 0 14px
}

.form-error {
  color: var(--red);
  font-size: 13px;
  font-weight: 600;
  margin: -6px 0 12px;
  display: none
}

.form-error.show {
  display: block;
  animation: fadeUp .3s ease
}

.auth-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 13.5px;
  margin: 4px 0 20px
}

.auth-row label {
  display: flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  font-weight: 600
}

.auth-row input[type=checkbox] {
  accent-color: var(--accent);
  width: 15px;
  height: 15px;
  cursor: pointer
}

.link {
  color: var(--accent);
  font-weight: 700;
  transition: .2s
}

.link:hover {
  text-shadow: 0 0 14px rgba(0, 212, 255, .6)
}

.auth-alt {
  text-align: center;
  font-size: 14px;
  color: var(--muted);
  margin-top: 20px
}

.demo-hint {
  margin-top: 18px;
  padding: 12px 15px;
  border-radius: 13px;
  background: rgba(255, 207, 77, .07);
  border: 1px dashed rgba(255, 207, 77, .4);
  font-size: 13px;
  color: var(--muted);
  line-height: 1.6
}

.demo-hint b {
  color: var(--yellow);
  font-family: 'JetBrains Mono', monospace
}

/* ---------- Dashboard ---------- */
.hero {
  padding: 34px;
  border-radius: 24px;
  position: relative;
  overflow: hidden;
  margin-bottom: 26px;
  animation: fadeUp .5s ease both
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 24px;
  padding: 1.5px;
  background: var(--grad);
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
  opacity: .8
}

.hero::after {
  content: "</>";
  position: absolute;
  right: 26px;
  top: 50%;
  transform: translateY(-50%);
  font-family: 'JetBrains Mono', monospace;
  font-size: clamp(70px, 12vw, 150px);
  font-weight: 700;
  color: rgba(255, 255, 255, .05);
  pointer-events: none;
  user-select: none
}

.hero h1 {
  font-size: clamp(26px, 4vw, 40px);
  margin-bottom: 10px
}

.hero p {
  color: var(--muted);
  font-size: 16px;
  max-width: 560px;
  line-height: 1.65
}

.stat-card {
  padding: 20px;
  border-radius: var(--radius);
  display: flex;
  gap: 15px;
  align-items: center;
  transition: .3s
}

.stat-card:hover {
  transform: translateY(-4px);
  border-color: var(--border2);
  box-shadow: var(--shadow)
}

.stat-ico {
  width: 48px;
  height: 48px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 22px;
  flex: none;
  background: var(--glass2);
  border: 1px solid var(--border)
}

.stat-num {
  font-size: 23px;
  font-weight: 800;
  font-family: 'Space Grotesk', sans-serif
}

.stat-label {
  font-size: 12.5px;
  color: var(--muted);
  font-weight: 600
}

.course-card {
  padding: 28px;
  border-radius: 22px;
  position: relative;
  overflow: hidden;
  cursor: pointer;
  transition: transform .3s, box-shadow .3s, border-color .3s;
  animation: fadeUp .5s ease both
}

.course-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow)
}

.course-card::before {
  content: "";
  position: absolute;
  top: -70px;
  right: -70px;
  width: 190px;
  height: 190px;
  border-radius: 50%;
  background: radial-gradient(circle, var(--cc2), transparent 70%);
  opacity: .5;
  transition: .4s
}

.course-card:hover::before {
  transform: scale(1.3);
  opacity: .8
}

.course-ico {
  width: 58px;
  height: 58px;
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 27px;
  font-weight: 800;
  margin-bottom: 16px;
  background: linear-gradient(135deg, var(--cc), var(--cc2));
  box-shadow: 0 10px 26px var(--cc-glow);
  color: #fff
}

.course-card h3 {
  font-size: 21px;
  margin-bottom: 7px
}

.course-card p {
  color: var(--muted);
  font-size: 14px;
  line-height: 1.6;
  margin-bottom: 18px
}

.c-html {
  --cc: #ff7a59;
  --cc2: #ff3d7f;
  --cc-glow: rgba(255, 90, 90, .35);
  --cc-soft: rgba(255, 122, 89, .12)
}

.c-css {
  --cc: #00d4ff;
  --cc2: #7c3aed;
  --cc-glow: rgba(0, 212, 255, .35);
  --cc-soft: rgba(0, 212, 255, .12)
}

.c-js {
  --cc: #ffcf4d;
  --cc2: #ff8a3d;
  --cc-glow: rgba(255, 207, 77, .35);
  --cc-soft: rgba(255, 207, 77, .12)
}

.course-card {
  background: linear-gradient(160deg, var(--cc-soft), var(--glass) 55%);
  border: 1px solid var(--border);
  backdrop-filter: blur(18px)
}

.pbar {
  height: 9px;
  border-radius: 99px;
  background: rgba(255, 255, 255, .09);
  overflow: hidden
}

.pbar i {
  display: block;
  height: 100%;
  border-radius: 99px;
  background: var(--grad);
  width: 0;
  transition: width 1.3s cubic-bezier(.22, 1, .36, 1)
}

.pbar-label {
  display: flex;
  justify-content: space-between;
  font-size: 12.5px;
  font-weight: 700;
  margin-bottom: 7px
}

.pbar-label b {
  color: var(--accent)
}

.tool-card {
  padding: 22px;
  border-radius: var(--radius);
  display: flex;
  flex-direction: column;
  gap: 10px;
  transition: .3s;
  cursor: pointer;
  align-items: flex-start
}

.tool-card:hover {
  transform: translateY(-5px);
  border-color: var(--accent);
  box-shadow: var(--glow)
}

.tool-ico {
  width: 46px;
  height: 46px;
  border-radius: 13px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 21px;
  background: var(--glass2);
  border: 1px solid var(--border)
}

.tool-card h4 {
  font-size: 15.5px
}

.tool-card p {
  font-size: 12.5px;
  color: var(--muted);
  line-height: 1.5
}

/* ---------- Course overview / lesson cards ---------- */
.course-banner {
  padding: 32px;
  border-radius: 22px;
  margin-bottom: 28px;
  position: relative;
  overflow: hidden;
  animation: fadeUp .5s ease both
}

.course-banner::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 22px;
  padding: 1.5px;
  background: linear-gradient(120deg, var(--cc), var(--cc2));
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
  opacity: .75
}

.course-banner .big {
  font-size: 46px;
  width: 74px;
  height: 74px;
  border-radius: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--cc), var(--cc2));
  box-shadow: 0 12px 30px var(--cc-glow);
  margin-bottom: 16px
}

.course-banner h1 {
  font-size: clamp(24px, 3.6vw, 34px);
  margin-bottom: 10px
}

.course-banner p {
  color: var(--muted);
  line-height: 1.7;
  max-width: 760px;
  font-size: 15px
}

.lesson-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(265px, 1fr));
  gap: 16px
}

.lesson-card {
  padding: 20px;
  border-radius: 18px;
  cursor: pointer;
  transition: .3s;
  position: relative;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  gap: 10px
}

.lesson-card:hover {
  transform: translateY(-5px);
  border-color: var(--border2);
  box-shadow: var(--shadow)
}

.lesson-card.done {
  border-color: rgba(47, 230, 166, .45)
}

.lesson-num {
  width: 38px;
  height: 38px;
  border-radius: 12px;
  background: var(--glass2);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 14px;
  font-family: 'JetBrains Mono', monospace;
  color: var(--muted)
}

.lesson-card.done .lesson-num {
  background: rgba(47, 230, 166, .15);
  border-color: rgba(47, 230, 166, .5);
  color: var(--green)
}

.lesson-card h4 {
  font-size: 15px;
  line-height: 1.4
}

.lesson-meta {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 11.5px;
  color: var(--muted);
  font-weight: 600;
  margin-top: auto
}

/* ---------- Lesson page ---------- */
.crumbs {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: 600;
  color: var(--muted);
  margin-bottom: 22px;
  flex-wrap: wrap
}

.crumbs a:hover {
  color: var(--accent)
}

.crumbs .sep {
  opacity: .4
}

.lesson-title {
  font-size: clamp(24px, 3.6vw, 34px);
  margin-bottom: 12px;
  animation: fadeUp .4s ease both
}

.lesson-desc {
  color: var(--muted);
  line-height: 1.75;
  font-size: 15.5px;
  max-width: 800px;
  margin-bottom: 26px;
  animation: fadeUp .5s .05s ease both
}

.lesson-sec {
  margin-bottom: 28px;
  animation: fadeUp .5s ease both
}

.lesson-sec h3 {
  font-size: 19px;
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 10px
}

.lesson-sec h3 .n {
  width: 30px;
  height: 30px;
  border-radius: 10px;
  background: var(--grad);
  color: #fff;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  flex: none
}

.video-container {
  width: 100%;
  aspect-ratio: 16/9;
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid var(--border);
  box-shadow: var(--shadow)
}

.video-container iframe {
  width: 100%;
  height: 100%;
  border: 0;
  border-radius: 16px;
  display: block
}

.video-thumb {
  position: relative;
  width: 100%;
  aspect-ratio: 16/9;
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  overflow: hidden;
  border: 1px solid var(--border);
  transition: .3s
}

.video-thumb:hover {
  border-color: var(--accent);
  box-shadow: 0 0 30px rgba(0, 212, 255, .25)
}

.video-thumb::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(600px 300px at 30% 20%, rgba(0, 212, 255, .25), transparent 60%), radial-gradient(500px 300px at 80% 80%, rgba(124, 58, 237, .3), transparent 60%), linear-gradient(150deg, #101a3d, #070b1c)
}

.video-thumb .t-play {
  position: relative;
  width: 64px;
  height: 64px;
  border-radius: 50%;
  background: var(--grad);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  color: #fff;
  padding-left: 4px;
  box-shadow: 0 0 40px rgba(0, 212, 255, .5);
  animation: pulse 2.2s infinite;
  transition: .3s
}

.video-thumb:hover .t-play {
  transform: scale(1.12)
}

@keyframes pulse {
  0% {
    box-shadow: 0 0 0 0 rgba(0, 212, 255, .45)
  }

  70% {
    box-shadow: 0 0 0 22px rgba(0, 212, 255, 0)
  }

  100% {
    box-shadow: 0 0 0 0 rgba(0, 212, 255, 0)
  }
}

.learn-list {
  list-style: none;
  display: grid;
  gap: 10px
}

.learn-list li {
  display: flex;
  gap: 11px;
  align-items: flex-start;
  padding: 12px 15px;
  border-radius: 13px;
  background: var(--glass);
  border: 1px solid var(--border);
  font-size: 14.5px;
  line-height: 1.55
}

.learn-list li::before {
  content: "✓";
  flex: none;
  width: 22px;
  height: 22px;
  border-radius: 8px;
  background: rgba(47, 230, 166, .15);
  color: var(--green);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  font-weight: 800;
  margin-top: 1px
}

.code-block {
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, .1);
  background: var(--codebg);
  box-shadow: 0 14px 40px rgba(0, 0, 0, .35)
}

.code-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 16px;
  background: rgba(255, 255, 255, .045);
  border-bottom: 1px solid rgba(255, 255, 255, .08);
  gap: 10px
}

.code-head .lang {
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px;
  letter-spacing: 1.5px;
  color: var(--accent);
  font-weight: 700;
  text-transform: uppercase
}

.code-head .dots {
  display: flex;
  gap: 6px
}

.code-head .dots i {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: #ff5f57
}

.code-head .dots i:nth-child(2) {
  background: #febc2e
}

.code-head .dots i:nth-child(3) {
  background: #28c840
}

.code-block pre {
  padding: 18px 20px;
  overflow-x: auto;
  font-size: 13.5px;
  line-height: 1.75;
  color: #c8d6f5;
  tab-size: 2
}

.code-block pre code {
  font-family: 'JetBrains Mono', monospace
}

.tk-tag {
  color: #ff8ab5
}

.tk-attr {
  color: #8be9fd
}

.tk-str {
  color: #a6e22e
}

.tk-kw {
  color: #ff79c6
}

.tk-com {
  color: #5f6f9e;
  font-style: italic
}

.tk-num {
  color: #bd93f9
}

.tk-prop {
  color: #8be9fd
}

.tk-val {
  color: #a6e22e
}

.tk-fn {
  color: #ffb86c
}

.activity-box {
  padding: 22px 24px;
  border-radius: 16px;
  background: var(--glass);
  border: 1px solid var(--border);
  border-left: 4px solid var(--yellow);
  line-height: 1.7;
  font-size: 14.5px
}

.activity-box b {
  color: var(--yellow)
}

.lesson-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  flex-wrap: wrap;
  margin-top: 34px;
  padding-top: 24px;
  border-top: 1px solid var(--border)
}

/* ---------- Videos page ---------- */
.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px
}

.video-card {
  border-radius: 22px;
  overflow: hidden;
  background: var(--glass);
  border: 1px solid var(--border);
  transition: .3s ease, border-color .3s ease;
}

.video-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow);
  border-color: var(--accent)
}

.video-card .video-thumb {
  display: grid;
  place-items: center;
  border: 0;
  border-radius: 0;
  aspect-ratio: 16/9;
  position: relative;
  overflow: hidden;
}

.video-card .video-thumb .video-label {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  padding: 12px 14px;
  background: linear-gradient(180deg, rgba(2, 8, 27, 0) 0%, rgba(2, 8, 27, .94) 100%);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  color: #fff;
  font-size: 13px;
  line-height: 1.2;
}

.video-card .video-thumb .video-label span {
  opacity: .9;
}

.video-card .video-thumb .video-label strong {
  font-size: 13px;
}

.video-card .video-thumb .t-play {
  z-index: 1;
}

.video-info {
  padding: 18px;
}

.video-card .video-thumb .t-play {
  width: 54px;
  height: 54px;
  font-size: 17px
}

.video-info {
  padding: 16px
}

.video-main-grid {
  display: grid;
  grid-template-columns: 1.7fr 1fr;
  gap: 24px;
  align-items: start;
  margin-top: 24px;
}

.video-player-panel,
.video-playlist-panel {
  border-radius: 28px;
  overflow: hidden;
  background: rgba(13, 20, 44, .82);
  border: 1px solid rgba(255, 255, 255, .06);
  box-shadow: 0 24px 70px rgba(7, 11, 25, .25);
}

.video-player-info {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
  padding: 24px;
  border-bottom: 1px solid rgba(255, 255, 255, .06);
}

.video-player-info h2 {
  font-size: 26px;
  margin: 0;
}

.video-player-info .muted {
  color: rgba(255, 255, 255, .65);
  margin-top: 8px;
  max-width: 520px;
}

.video-player-frame {
  padding: 24px;
}

.main-video {
  width: 100%;
  height: auto;
  border-radius: 20px;
  background: #000;
  border: 1px solid rgba(255, 255, 255, .08);
  box-shadow: 0 24px 40px rgba(0, 0, 0, .35);
}

.video-fallback {
  min-height: 320px;
  display: grid;
  place-items: center;
  border-radius: 20px;
  background: rgba(255, 255, 255, .02);
  border: 1px dashed rgba(255, 255, 255, .1);
  color: rgba(255, 255, 255, .75);
}

.video-playlist-panel {
  display: flex;
  flex-direction: column;
  min-height: 680px;
}

.playlist-header {
  padding: 24px;
  border-bottom: 1px solid rgba(255, 255, 255, .06);
}

.playlist-header h3 {
  margin: 0 0 10px;
}

.playlist-list {
  display: grid;
  gap: 14px;
  padding: 24px;
  overflow: auto;
  max-height: calc(100vh - 220px);
}

.video-playlist-card {
  display: grid;
  grid-template-columns: 72px 1fr auto;
  gap: 14px;
  align-items: center;
  padding: 18px 18px 18px 16px;
  border-radius: 18px;
  background: rgba(255, 255, 255, .025);
  border: 1px solid rgba(255, 255, 255, .06);
  color: #fff;
  text-align: left;
  cursor: pointer;
  transition: transform .2s ease, border-color .2s ease, background .2s ease;
}

.video-playlist-card:hover {
  transform: translateX(3px);
  border-color: rgba(0, 215, 255, .25);
  background: rgba(0, 215, 255, .06);
}

.video-playlist-card.active {
  border-color: rgba(0, 255, 191, .3);
  background: rgba(0, 255, 191, .08);
}

.playlist-thumb {
  width: 72px;
  height: 72px;
  border-radius: 18px;
  display: grid;
  place-items: center;
  background: rgba(255, 255, 255, .06);
  color: #fff;
  flex-shrink: 0;
}

.playlist-meta strong {
  display: block;
  font-size: 15px;
  line-height: 1.4;
  margin-bottom: 8px;
}

.playlist-meta .badge {
  display: inline-flex;
  padding: 4px 10px;
  border-radius: 999px;
  font-size: 12px;
}

.playlist-status {
  color: rgba(255, 255, 255, .7);
  font-size: 13px;
  white-space: nowrap;
}

.playlist-tabs {
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 10px;
}

@media (max-width: 1080px) {
  .video-main-grid {
    grid-template-columns: 1fr;
  }

  .video-playlist-panel {
    min-height: auto;
  }
}

@media (max-width: 720px) {
  .video-player-info {
    flex-direction: column;
    align-items: stretch;
  }

  .video-playlist-card {
    grid-template-columns: 1fr;
  }

  .playlist-status {
    margin-top: 10px;
  }
}

.video-info h4 {
  font-size: 14.5px;
  line-height: 1.45;
  margin-bottom: 7px
}

.video-info .row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 12px;
  color: var(--muted);
  font-weight: 600
}

.video-info .watched {
  color: var(--green)
}

/* ---------- Practice / quizzes ---------- */
.tabs {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 24px
}

.tab {
  padding: 11px 22px;
  border-radius: 12px;
  font-weight: 700;
  font-size: 14px;
  background: var(--glass2);
  border: 1px solid var(--border);
  color: var(--muted);
  transition: .25s
}

.tab:hover {
  color: var(--text);
  border-color: var(--border2)
}

.tab.active {
  background: var(--grad);
  color: #fff;
  box-shadow: 0 6px 20px rgba(124, 58, 237, .35);
  border-color: transparent
}

.quiz-card {
  padding: 32px;
  border-radius: 22px;
  max-width: 760px;
  margin: 0 auto;
  animation: fadeUp .45s ease both
}

.q-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
  gap: 12px;
  flex-wrap: wrap
}

.q-count {
  font-size: 13px;
  font-weight: 800;
  color: var(--muted);
  font-family: 'JetBrains Mono', monospace
}

.q-score {
  padding: 7px 15px;
  border-radius: 99px;
  background: rgba(255, 207, 77, .12);
  border: 1px solid rgba(255, 207, 77, .35);
  color: var(--yellow);
  font-weight: 800;
  font-size: 13px
}

.q-bar {
  height: 7px;
  border-radius: 99px;
  background: rgba(255, 255, 255, .09);
  overflow: hidden;
  margin-bottom: 26px
}

.q-bar i {
  display: block;
  height: 100%;
  border-radius: 99px;
  background: var(--grad);
  transition: width .5s ease
}

.quiz-q {
  font-size: 19px;
  font-weight: 700;
  line-height: 1.5;
  margin-bottom: 22px
}

.quiz-opt {
  display: flex;
  gap: 13px;
  width: 100%;
  text-align: left;
  padding: 14px 16px;
  border-radius: 14px;
  background: var(--glass2);
  border: 1px solid var(--border);
  color: var(--text);
  font-size: 15px;
  transition: .2s;
  margin-bottom: 11px;
  align-items: center
}

.quiz-opt:hover:not(.locked) {
  border-color: var(--accent);
  transform: translateX(5px)
}

.opt-letter {
  width: 31px;
  height: 31px;
  border-radius: 9px;
  background: rgba(255, 255, 255, .09);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 13px;
  flex: none
}

.quiz-opt.correct {
  border-color: var(--green);
  background: rgba(47, 230, 166, .13)
}

.quiz-opt.correct .opt-letter {
  background: var(--green);
  color: #03251a
}

.quiz-opt.wrong {
  border-color: var(--red);
  background: rgba(255, 93, 122, .13)
}

.quiz-opt.wrong .opt-letter {
  background: var(--red);
  color: #fff
}

.quiz-opt.locked {
  cursor: default;
  opacity: .8
}

.quiz-fb {
  display: none;
  margin-top: 18px;
  padding: 16px 18px;
  border-radius: 14px;
  font-size: 14.5px;
  line-height: 1.65;
  animation: fadeUp .35s ease
}

.quiz-fb.show {
  display: block
}

.quiz-fb.good {
  background: rgba(47, 230, 166, .1);
  border: 1px solid rgba(47, 230, 166, .4)
}

.quiz-fb.bad {
  background: rgba(255, 93, 122, .1);
  border: 1px solid rgba(255, 93, 122, .4)
}

.quiz-fb b {
  display: block;
  margin-bottom: 4px;
  font-size: 15px
}

.result-wrap {
  text-align: center;
  padding: 20px 0;
  animation: pop .5s ease both
}

.ring-wrap {
  position: relative;
  width: 158px;
  height: 158px;
  margin: 6px auto 22px
}

.ring-wrap svg {
  transform: rotate(-90deg)
}

.ring-bg {
  fill: none;
  stroke: rgba(255, 255, 255, .09);
  stroke-width: 11
}

.ring-fg {
  fill: none;
  stroke: url(#gradRing);
  stroke-width: 11;
  stroke-linecap: round;
  transition: stroke-dashoffset 1.4s cubic-bezier(.22, 1, .36, 1)
}

.ring-num {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center
}

.ring-num b {
  font-size: 36px;
  font-family: 'Space Grotesk', sans-serif
}

.ring-num span {
  font-size: 12px;
  color: var(--muted);
  font-weight: 700
}

.result-msg {
  font-size: clamp(22px, 3vw, 30px);
  font-weight: 700;
  margin-bottom: 10px
}

.result-sub {
  color: var(--muted);
  margin-bottom: 24px;
  line-height: 1.6
}

/* ---------- Projects ---------- */
.proj-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(270px, 1fr));
  gap: 18px
}

.proj-card {
  padding: 24px;
  border-radius: 20px;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: .3s;
  animation: fadeUp .5s ease both
}

.proj-card:hover {
  transform: translateY(-5px);
  border-color: var(--accent);
  box-shadow: var(--glow)
}

.proj-ico {
  width: 52px;
  height: 52px;
  border-radius: 15px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  background: var(--glass2);
  border: 1px solid var(--border)
}

.proj-card h4 {
  font-size: 16.5px
}

.proj-card p {
  font-size: 13px;
  color: var(--muted);
  line-height: 1.6;
  flex: 1
}

.diff {
  display: flex;
  gap: 4px;
  font-size: 12px
}

.diff .star {
  color: var(--yellow)
}

.diff .star.off {
  opacity: .25
}

.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(3, 6, 16, .72);
  backdrop-filter: blur(8px);
  z-index: 120;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 22px;
  animation: fadeUp .25s ease;
  overflow-y: auto
}

.modal {
  width: min(860px, 100%);
  max-height: 92vh;
  overflow-y: auto;
  border-radius: 22px;
  padding: 30px;
  position: relative;
  animation: pop .35s ease both;
  background: var(--glass);
  backdrop-filter: blur(28px);
  -webkit-backdrop-filter: blur(28px);
  border: 1px solid var(--border2);
  box-shadow: var(--shadow)
}

.modal-close {
  position: absolute;
  top: 16px;
  right: 16px;
  width: 36px;
  height: 36px;
  border-radius: 11px;
  background: var(--glass2);
  border: 1px solid var(--border);
  font-size: 15px;
  transition: .25s;
  z-index: 5
}

.modal-close:hover {
  background: rgba(255, 93, 122, .2);
  border-color: var(--red);
  color: var(--red)
}

.proj-steps {
  list-style: none;
  counter-reset: st;
  display: grid;
  gap: 10px
}

.proj-steps li {
  counter-increment: st;
  display: flex;
  gap: 12px;
  align-items: flex-start;
  font-size: 14px;
  line-height: 1.6;
  padding: 11px 14px;
  border-radius: 13px;
  background: var(--glass);
  border: 1px solid var(--border)
}

.proj-steps li::before {
  content: counter(st);
  flex: none;
  width: 26px;
  height: 26px;
  border-radius: 9px;
  background: var(--grad);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12.5px;
  font-weight: 800
}

.learn-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 8px
}

.learn-chips span {
  padding: 6px 13px;
  border-radius: 99px;
  font-size: 12.5px;
  font-weight: 700;
  background: rgba(0, 212, 255, .1);
  border: 1px solid rgba(0, 212, 255, .3);
  color: var(--accent)
}

.preview-frame {
  width: 100%;
  height: 430px;
  border: 0;
  border-radius: 14px;
  background: #fff;
  box-shadow: inset 0 0 0 1px rgba(0, 0, 0, .06)
}

/* ---------- Cheat sheets ---------- */
.cheat-sec {
  margin-bottom: 26px;
  animation: fadeUp .5s ease both
}

.cheat-sec h3 {
  font-size: 17px;
  margin-bottom: 12px;
  color: var(--accent)
}

.cheat-table {
  overflow: hidden;
  border-radius: 16px;
  border: 1px solid var(--border)
}

.cheat-row {
  display: grid;
  grid-template-columns: minmax(150px, 1.1fr) minmax(200px, 1.6fr) minmax(180px, 1.5fr);
  gap: 14px;
  padding: 13px 16px;
  align-items: center;
  border-bottom: 1px solid var(--border);
  background: var(--glass);
  transition: .2s
}

.cheat-row:last-child {
  border-bottom: 0
}

.cheat-row:hover {
  background: var(--glass2)
}

.cheat-term {
  font-family: 'JetBrains Mono', monospace;
  font-size: 13px;
  font-weight: 700;
  color: var(--yellow)
}

.cheat-desc {
  font-size: 13.5px;
  color: var(--muted);
  line-height: 1.5
}

.cheat-ex {
  background: var(--codebg);
  border: 1px solid rgba(255, 255, 255, .09);
  border-radius: 11px;
  padding: 10px 12px;
  font-size: 12px;
  color: #c8d6f5;
  overflow-x: auto;
  display: flex;
  align-items: center;
  gap: 8px;
  justify-content: space-between
}

.cheat-ex code {
  font-family: 'JetBrains Mono', monospace;
  white-space: pre
}

.cheat-ex .copy-btn {
  flex: none;
  padding: 5px 10px;
  font-size: 11px
}

/* ---------- Playground ---------- */
.pg-editor {
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid var(--border);
  background: var(--codebg);
  box-shadow: 0 14px 40px rgba(0, 0, 0, .3)
}

.pg-editor textarea {
  width: 100%;
  min-height: 250px;
  background: var(--codebg);
  border: 0;
  outline: none;
  color: #c8d6f5;
  padding: 18px 20px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 13.5px;
  line-height: 1.7;
  resize: vertical;
  tab-size: 2;
  white-space: pre
}

.pg-editor textarea::selection {
  background: rgba(0, 212, 255, .35)
}

.pg-preview {
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid var(--border);
  background: #fff
}

.pg-preview .preview-frame {
  height: 460px;
  display: block;
  width: 100%
}

.pg-select {
  padding: 10px 15px;
  border-radius: 12px;
  background: var(--glass2);
  border: 1px solid var(--border);
  color: var(--text);
  font-size: 14px;
  font-weight: 600;
  outline: none;
  cursor: pointer
}

.pg-select option {
  background: #0b1226;
  color: #eaf0ff
}

/* ---------- Profile / progress ---------- */
.avatar-lg {
  width: 86px;
  height: 86px;
  border-radius: 50%;
  background: var(--grad);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 30px;
  font-weight: 800;
  color: #fff;
  box-shadow: 0 0 40px rgba(124, 58, 237, .5);
  flex: none
}

.info-row {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 13px 16px;
  border-radius: 13px;
  background: var(--glass);
  border: 1px solid var(--border);
  font-size: 14px;
  margin-bottom: 10px
}

.info-row .k {
  color: var(--muted);
  min-width: 130px;
  font-weight: 600
}

.info-row .v {
  font-weight: 700;
  word-break: break-all
}

.score-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 15px;
  border-radius: 99px;
  font-weight: 800;
  font-size: 13px;
  background: var(--glass2);
  border: 1px solid var(--border);
  font-family: 'JetBrains Mono', monospace
}

.score-chip.good {
  border-color: rgba(47, 230, 166, .4);
  color: var(--green)
}

.score-chip.mid {
  border-color: rgba(255, 207, 77, .4);
  color: var(--yellow)
}

.score-chip.low {
  border-color: rgba(255, 93, 122, .4);
  color: var(--red)
}

.big-stat {
  text-align: center;
  padding: 26px 14px
}

.big-stat b {
  font-size: 34px;
  font-family: 'Space Grotesk', sans-serif;
  display: block;
  background: var(--grad);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent
}

.big-stat span {
  font-size: 12.5px;
  color: var(--muted);
  font-weight: 600
}

/* ---------- Toasts & modal ---------- */
.toasts {
  position: fixed;
  bottom: 22px;
  right: 22px;
  z-index: 300;
  display: flex;
  flex-direction: column;
  gap: 10px
}

.toast {
  padding: 14px 19px;
  border-radius: 15px;
  background: var(--glass);
  backdrop-filter: blur(18px);
  border: 1px solid var(--border2);
  box-shadow: var(--shadow);
  font-weight: 600;
  font-size: 14px;
  display: flex;
  gap: 10px;
  align-items: center;
  animation: toastIn .4s cubic-bezier(.22, 1, .36, 1) both;
  max-width: 360px
}

.toast.t-success {
  border-color: rgba(47, 230, 166, .55)
}

.toast.t-error {
  border-color: rgba(255, 93, 122, .55)
}

.toast.t-info {
  border-color: rgba(0, 212, 255, .55)
}

.toast.out {
  animation: toastOut .35s ease both
}

@keyframes toastIn {
  from {
    transform: translateX(130%);
    opacity: 0
  }

  to {
    transform: none;
    opacity: 1
  }
}

@keyframes toastOut {
  to {
    transform: translateX(130%);
    opacity: 0
  }
}

/* ---------- Responsive ---------- */
@media (max-width:1150px) {
  .nav {
    width: calc(100% - 24px);
    padding: 12px 16px;
  }

  .nav-links {
    gap: 10px;
    margin: 0 8px;
  }

  .nav-link {
    padding: 9px 12px;
    font-size: 13px;
  }

  .hamburger {
    display: flex;
  }

  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width:980px) {
  .nav {
    padding: 12px 14px;
  }

  .nav-links {
    margin: 0 6px;
  }

  .nav-link {
    padding: 9px 10px;
    font-size: 12.8px;
  }

  .logo-text {
    display: inline-block;
  }

  .nav-right {
    gap: 8px;
  }
}

@media (max-width:860px) {
  .nav {
    min-height: 60px;
    padding: 12px 14px;
  }

  .nav-links {
    display: none;
  }

  .nav-right {
    gap: 8px;
  }

  .hamburger {
    display: flex;
  }
}

@media (max-width:680px) {
  .logo-text {
    font-size: 15px;
  }

  .nav {
    padding: 10px 12px;
  }

  .icon-btn,
  .hamburger,
  .user-chip {
    min-width: 44px;
    min-height: 44px;
  }

  .user-chip {
    padding: 8px 10px;
    gap: 8px;
  }

  .user-chip .u-name {
    max-width: 100px;
  }
}

@media (max-width:560px) {
  .nav {
    width: calc(100% - 16px);
    padding: 10px 12px;
  }

  .logo {
    gap: 8px;
  }

  .nav-right {
    gap: 6px;
  }

  .user-chip {
    display: none;
  }
}

/* ============================================================
   ABOUT DEVELOPER — Dula Dev
   ============================================================ */
.about-hero {
  display: grid;
  grid-template-columns: 320px 1fr;
  gap: 32px;
  align-items: center;
  padding: 36px;
  border-radius: 24px;
  margin-bottom: 32px;
  position: relative;
  overflow: hidden;
}

.about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 24px;
  padding: 1.5px;
  background: linear-gradient(120deg, #00d4ff, #7c3aed 55%, #ff2ec4);
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
  opacity: .9
}

.about-photo-wrap {
  position: relative;
  width: 100%;
  aspect-ratio: 1/1;
  border-radius: 22px;
  overflow: hidden;
  background: #0b1226;
  border: 1px solid rgba(255, 255, 255, .1);
  box-shadow: 0 20px 60px rgba(0, 0, 0, .5), 0 0 50px rgba(0, 212, 255, .18);
}

.about-photo-wrap img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.about-photo-wrap::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, transparent 50%, rgba(0, 0, 0, .5));
}

.about-hero h1 {
  font-size: clamp(26px, 3.5vw, 36px);
  margin-bottom: 6px
}

.about-hero h2 {
  font-size: 19px;
  color: var(--accent);
  margin-bottom: 16px;
  font-weight: 700
}

.about-hero .lead {
  color: var(--muted);
  line-height: 1.8;
  font-size: 15.5px
}

.about-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 7px 14px;
  border-radius: 99px;
  background: rgba(0, 212, 255, .1);
  border: 1px solid rgba(0, 212, 255, .3);
  color: var(--accent);
  font-weight: 700;
  font-size: 13px;
  margin-bottom: 14px
}

.about-section {
  padding: 28px;
  border-radius: 22px;
  margin-bottom: 22px;
  animation: fadeUp .5s ease both;
}

.about-section h2 {
  font-size: 22px;
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 12px
}

.about-section h2 .ico {
  width: 42px;
  height: 42px;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--accent), var(--violet));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  color: #fff;
  box-shadow: 0 8px 22px rgba(0, 212, 255, .3)
}

.about-section h3 {
  font-size: 18px;
  margin: 22px 0 12px;
  color: var(--text)
}

.about-section p {
  color: var(--muted);
  line-height: 1.85;
  font-size: 15px;
  margin-bottom: 12px
}

.about-section ul {
  list-style: none;
  display: grid;
  gap: 10px;
  margin: 12px 0 18px
}

.about-section ul li {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 12px 14px;
  border-radius: 13px;
  background: var(--glass);
  border: 1px solid var(--border);
  font-size: 14.5px;
  line-height: 1.6
}

.about-section ul li::before {
  content: "•";
  color: var(--accent);
  font-weight: 900;
  font-size: 18px;
  flex: none;
  margin-top: -2px
}

.about-list-check li::before {
  content: "✓" !important;
  background: rgba(47, 230, 166, .15);
  color: var(--green) !important;
  width: 22px;
  height: 22px;
  border-radius: 7px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px
}

.about-quote {
  padding: 20px 22px;
  border-left: 4px solid var(--accent);
  background: linear-gradient(90deg, rgba(0, 212, 255, .08), transparent);
  border-radius: 0 14px 14px 0;
  font-style: italic;
  color: var(--text);
  font-weight: 600;
  margin: 18px 0;
  font-size: 16px;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, .06)
}

/* Professional Standards — programming languages grid like the reference image */
.standards-wrap {
  position: relative;
  padding: 36px 28px;
  border-radius: 22px;
  background:
    radial-gradient(800px 400px at 20% 0%, rgba(0, 255, 170, .06), transparent 60%),
    radial-gradient(700px 500px at 80% 100%, rgba(0, 255, 170, .04), transparent 60%),
    linear-gradient(180deg, rgba(4, 7, 15, .98), rgba(5, 9, 20, .98)),
    url("data:image/svg+xml,%3Csvg width='100' height='100' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M0 0 L100 0 L100 100 L0 100 Z' fill='none' stroke='rgba(255,255,255,0.03)'/%3E%3C/svg%3E");
  border: 1px solid rgba(255, 255, 255, .06);
  overflow: hidden;
  margin: 18px 0 24px;
}

.standards-wrap::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(0, 255, 120, .08) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 255, 120, .06) 1px, transparent 1px);
  background-size: 52px 52px;
  opacity: .12;
  pointer-events: none;
}

.standards-header {
  text-align: center;
  position: relative;
  z-index: 1;
  margin-bottom: 26px
}

.standards-header h2 {
  justify-content: center;
  font-size: 28px
}

.standards-header p {
  max-width: 620px;
  margin: 12px auto 0;
  color: #7a8db0;
  line-height: 1.6;
  font-size: 14px
}

.standards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(148px, 1fr));
  gap: 14px;
  position: relative;
  z-index: 1;
}

.standard-card {
  position: relative;
  padding: 22px 16px 18px;
  border-radius: 16px;
  background: linear-gradient(180deg, rgba(255, 255, 255, .035), rgba(255, 255, 255, .015));
  border: 1px solid rgba(255, 255, 255, .07);
  text-align: center;
  transition: .3s;
  backdrop-filter: blur(10px);
  overflow: hidden;
}

.standard-card::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 16px;
  padding: 1px;
  background: linear-gradient(135deg, var(--clr, rgba(0, 212, 255, .5)), transparent 60%);
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  opacity: .7;
  transition: .3s
}

.standard-card:hover {
  transform: translateY(-5px);
  border-color: rgba(255, 255, 255, .15);
  box-shadow: 0 16px 40px rgba(0, 0, 0, .5), 0 0 24px color-mix(in srgb, var(--clr) 18%, transparent);
}

.standard-card:hover::before {
  opacity: 1
}

.s-icon {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 12px;
  font-size: 22px;
  background: rgba(255, 255, 255, .06);
  border: 1px solid rgba(255, 255, 255, .08);
  color: var(--clr);
  box-shadow: 0 0 18px color-mix(in srgb, var(--clr) 20%, transparent);
}

.standard-card span:last-child {
  font-weight: 700;
  font-size: 13.5px;
  color: #d0dbf5;
  letter-spacing: .2px
}

.teams-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 16px;
  margin: 16px 0
}

.team-card {
  padding: 20px;
  border-radius: 16px;
  background: var(--glass);
  border: 1px solid var(--border);
  transition: .3s
}

.team-card:hover {
  transform: translateY(-4px);
  border-color: var(--border2);
  box-shadow: var(--shadow)
}

.team-card h4 {
  font-size: 15px;
  margin-bottom: 6px
}

.team-card p {
  font-size: 13.5px;
  color: var(--muted);
  line-height: 1.6;
  margin: 0
}

.info-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 12px;
  margin: 16px 0
}

.info-pill {
  padding: 14px 16px;
  border-radius: 14px;
  background: var(--glass);
  border: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 4px
}

.info-pill b {
  font-size: 13px;
  color: var(--muted);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .6px
}

.info-pill span {
  font-size: 15px;
  font-weight: 700;
  color: var(--text)
}

.mantra {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 18px 0
}

.mantra span {
  padding: 8px 16px;
  border-radius: 99px;
  background: rgba(0, 212, 255, .1);
  border: 1px solid rgba(0, 212, 255, .25);
  color: var(--accent);
  font-weight: 700;
  font-size: 13px;
  font-family: 'JetBrains Mono', monospace
}

@media (max-width:920px) {
  .about-hero {
    grid-template-columns: 1fr;
    gap: 22px
  }

  .about-photo-wrap {
    max-width: 320px;
    margin: 0 auto
  }
}

@media (max-width:640px) {
  #app {
    padding: 96px 14px 60px
  }

  .hero {
    padding: 26px 22px
  }

  .hero::after {
    font-size: 80px;
    right: 16px
  }

  .grid-4 {
    grid-template-columns: 1fr 1fr
  }

  .auth-points {
    grid-template-columns: 1fr
  }

  .lesson-nav {
    flex-direction: column;
    align-items: stretch
  }

  .lesson-nav .btn {
    width: 100%
  }

  .toasts {
    left: 14px;
    right: 14px;
    bottom: 14px
  }

  .toast {
    max-width: none
  }

  .stat-card {
    padding: 16px
  }

  .user-chip .u-name {
    display: none
  }

  .modal {
    padding: 22px
  }

  .symbol {
    display: none
  }

  .preview-frame {
    height: 340px
  }

  .about-hero {
    padding: 22px
  }

  .standards-wrap {
    padding: 22px 16px
  }

  .standards-grid {
    grid-template-columns: repeat(2, 1fr)
  }
}