/* Codeglass — design system
   Light liquid-glass theme. One accent (cobalt), one support (teal),
   one neutral scale. Glass is layered translucency + edge light, not glow. */

:root {
  --bg: #f4f7fa;
  --bg-2: #ecf1f6;
  --ink: #101418;
  --ink-2: #3c4753;
  --ink-3: #67747f;
  --line: rgba(16, 20, 24, 0.09);
  --accent: #1a4be0;
  --accent-ink: #ffffff;
  --accent-soft: rgba(26, 75, 224, 0.08);
  --teal: #0d7480;
  --ok: #1a7f4e;
  --ok-soft: rgba(26, 127, 78, 0.1);
  --bad: #c2332f;
  --bad-soft: rgba(194, 51, 47, 0.08);

  --glass-bg: rgba(255, 255, 255, 0.55);
  --glass-brd: rgba(255, 255, 255, 0.65);
  --glass-shadow: 0 1px 2px rgba(16, 20, 24, 0.04), 0 12px 32px -12px rgba(16, 20, 24, 0.12);

  --font-sans: "Space Grotesk", -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, Menlo, Consolas, monospace;

  --r-s: 10px;
  --r-m: 16px;
  --r-l: 24px;
  --r-pill: 999px;

  --nav-h: 72px;
  --max-w: 1200px;
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--ink);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}
img, canvas, svg { display: block; max-width: 100%; }
a { color: var(--accent); text-decoration: none; }
button { font: inherit; cursor: pointer; }
code, pre, .mono { font-family: var(--font-mono); }

::selection { background: rgba(26, 75, 224, 0.18); }

/* ---------- type ---------- */
h1, h2, h3 { line-height: 1.12; letter-spacing: -0.02em; margin: 0; text-wrap: balance; }
.h-display { font-size: clamp(2.5rem, 5.2vw + 1rem, 4.5rem); font-weight: 700; }
.h-1 { font-size: clamp(2rem, 3.4vw + 0.8rem, 3rem); font-weight: 700; }
.h-2 { font-size: clamp(1.4rem, 1.8vw + 0.6rem, 1.9rem); font-weight: 600; }
.lede { font-size: clamp(1.05rem, 0.6vw + 0.95rem, 1.25rem); color: var(--ink-2); max-width: 56ch; margin: 0; }
.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--teal);
  margin: 0 0 14px;
}

/* ---------- layout ---------- */
.wrap { max-width: var(--max-w); margin-inline: auto; padding-inline: 24px; }
.section { padding-block: clamp(56px, 6.5vw, 88px); position: relative; }
.section-head { max-width: 640px; margin-bottom: clamp(36px, 5vw, 56px); }
.stack-16 > * + * { margin-top: 16px; }
.stack-24 > * + * { margin-top: 24px; }

/* ---------- glass ---------- */
.glass {
  position: relative;
  background: var(--glass-bg);
  -webkit-backdrop-filter: blur(18px) saturate(1.5);
  backdrop-filter: blur(18px) saturate(1.5);
  border: 1px solid var(--glass-brd);
  border-radius: var(--r-l);
  box-shadow: var(--glass-shadow);
}
/* refracted edge light: a crisp inner line + a faint dispersion rim */
.glass::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  padding: 1px;
  background: linear-gradient(135deg,
    rgba(255, 255, 255, 0.9),
    rgba(255, 255, 255, 0.1) 30%,
    rgba(26, 75, 224, 0.12) 60%,
    rgba(13, 116, 128, 0.18));
  -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
}
.glass::after {
  content: "";
  position: absolute;
  inset: 1px;
  border-radius: inherit;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.5), transparent 18%);
  pointer-events: none;
}
.glass > * { position: relative; }

.card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--r-m);
  box-shadow: 0 1px 2px rgba(16, 20, 24, 0.05);
}

/* ---------- buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 48px;
  padding: 0 24px;
  border-radius: var(--r-pill);
  border: 1px solid transparent;
  font-weight: 600;
  font-size: 0.98rem;
  white-space: nowrap;
  transition: transform 0.25s var(--ease-out), box-shadow 0.25s var(--ease-out),
    background 0.2s ease, border-color 0.2s ease;
}
.btn:active { transform: translateY(1px) scale(0.99); }
.btn-primary {
  background: var(--accent);
  color: var(--accent-ink);
  box-shadow: 0 1px 2px rgba(26, 75, 224, 0.3), 0 8px 20px -8px rgba(26, 75, 224, 0.5);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 2px 4px rgba(26, 75, 224, 0.3), 0 14px 28px -10px rgba(26, 75, 224, 0.55); }
.btn-ghost {
  background: rgba(255, 255, 255, 0.6);
  border-color: var(--line);
  color: var(--ink);
}
.btn-ghost:hover { border-color: rgba(16, 20, 24, 0.22); transform: translateY(-2px); }
.btn[disabled] { opacity: 0.55; pointer-events: none; }

/* ---------- nav ---------- */
.nav {
  position: fixed;
  inset-inline: 0;
  top: 0;
  z-index: 50;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  background: rgba(244, 247, 250, 0.7);
  -webkit-backdrop-filter: blur(16px) saturate(1.4);
  backdrop-filter: blur(16px) saturate(1.4);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s ease;
}
.nav.scrolled { border-bottom-color: var(--line); }
.nav .wrap { width: 100%; display: flex; align-items: center; gap: 24px; }
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.12rem;
  letter-spacing: -0.01em;
  color: var(--ink);
}
.brand-mark { width: 28px; height: 28px; }
.nav-links { display: flex; gap: 4px; margin-left: auto; align-items: center; }
.nav-links a {
  color: var(--ink-2);
  font-size: 0.95rem;
  font-weight: 500;
  padding: 8px 14px;
  border-radius: var(--r-pill);
  transition: color 0.2s ease, background 0.2s ease;
}
.nav-links a:hover { color: var(--ink); background: rgba(16, 20, 24, 0.05); }
.nav-links .btn { min-height: 40px; padding: 0 18px; }

/* ---------- hero ---------- */
.hero {
  position: relative;
  min-height: 100svh;
  display: flex;
  align-items: center;
  padding-top: var(--nav-h);
  overflow: hidden;
}
#glass-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}
.hero .wrap { position: relative; width: 100%; }
.hero-inner { max-width: 640px; padding-block: 96px; }
.hero-panel {
  padding: clamp(28px, 4vw, 48px);
  border-radius: var(--r-l);
}
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 32px; }
.hero-proof {
  display: flex;
  gap: 24px;
  margin-top: 40px;
  font-size: 0.92rem;
  color: var(--ink-3);
}
.hero-proof strong { display: block; font-size: 1.3rem; color: var(--ink); letter-spacing: -0.01em; }

.hero-line { display: block; }
.accent-word { color: var(--accent); }

/* ---------- track cards ---------- */
.tracks-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
}
.track-card {
  display: block;
  padding: 28px;
  border-radius: var(--r-l);
  color: var(--ink);
  transition: transform 0.35s var(--ease-out), box-shadow 0.35s var(--ease-out);
}
.track-card:hover { transform: translateY(-4px); box-shadow: 0 2px 4px rgba(16,20,24,0.05), 0 20px 40px -16px rgba(16,20,24,0.18); }
.track-card .lang-mark {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.85rem;
  margin-bottom: 20px;
  color: #fff;
}
.track-card h3 { font-size: 1.25rem; margin-bottom: 8px; }
.track-card p { color: var(--ink-2); font-size: 0.95rem; margin: 0 0 16px; }
.track-card .meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-3);
}
.track-card .go { color: var(--accent); font-weight: 600; }

/* ---------- how checking works ---------- */
.checker-demo {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  align-items: stretch;
}
@media (max-width: 840px) { .checker-demo { grid-template-columns: 1fr; } }
.demo-editor { padding: 0; overflow: hidden; display: flex; flex-direction: column; }
.demo-editor .editor-head {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-3);
}
.dot { width: 10px; height: 10px; border-radius: 50%; }
.demo-editor textarea {
  flex: 1;
  min-height: 180px;
  border: 0;
  outline: 0;
  resize: none;
  padding: 20px;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--ink);
  background: transparent;
}
.demo-editor .editor-foot { padding: 16px; border-top: 1px solid var(--line); display: flex; gap: 12px; align-items: center; }
.demo-rules { padding: 28px; display: flex; flex-direction: column; gap: 16px; }
.rule-row { display: flex; gap: 12px; align-items: flex-start; }
.rule-row .k {
  flex: none;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 4px 10px;
  border-radius: var(--r-pill);
  margin-top: 2px;
}
.rule-row .k.strict { background: var(--bad-soft); color: var(--bad); }
.rule-row .k.loose { background: var(--ok-soft); color: var(--ok); }
.rule-row p { margin: 0; color: var(--ink-2); font-size: 0.95rem; }
.demo-verdict { font-family: var(--font-mono); font-size: 0.85rem; min-height: 1.4em; }
.demo-verdict.ok { color: var(--ok); }
.demo-verdict.bad { color: var(--bad); }

/* ---------- curriculum preview ---------- */
.curr-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 20px; }
.curr-card { padding: 28px; }
.curr-card ol { margin: 16px 0 0; padding: 0; list-style: none; counter-reset: step; }
.curr-card li {
  counter-increment: step;
  display: flex;
  gap: 12px;
  align-items: baseline;
  padding: 10px 0;
  border-top: 1px solid var(--line);
  font-size: 0.95rem;
  color: var(--ink-2);
}
.curr-card li::before {
  content: counter(step, decimal-leading-zero);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--ink-3);
  flex: none;
}

/* ---------- CTA band ---------- */
.cta-band { padding: clamp(40px, 6vw, 72px); text-align: center; }
.cta-band .lede { margin-inline: auto; }

/* ---------- footer ---------- */
.footer {
  border-top: 1px solid var(--line);
  padding: 48px 0;
  color: var(--ink-3);
  font-size: 0.9rem;
}
.footer .wrap { display: flex; gap: 24px; flex-wrap: wrap; align-items: center; justify-content: space-between; }
.footer a { color: var(--ink-2); }

/* ---------- reveal on scroll ---------- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s var(--ease-out), transform 0.7s var(--ease-out);
  transition-delay: var(--d, 0s);
}
.reveal.in { opacity: 1; transform: none; }

/* ---------- auth pages ---------- */
.auth-wrap {
  min-height: 100svh;
  display: grid;
  place-items: center;
  padding: 96px 24px 48px;
  position: relative;
  overflow: hidden;
}
.auth-card { width: 100%; max-width: 420px; padding: 36px; }
.auth-card h1 { font-size: 1.5rem; margin: 0 0 8px; }
.auth-card .sub { color: var(--ink-2); font-size: 0.95rem; margin: 0 0 24px; }
.field label { display: block; font-size: 0.85rem; font-weight: 600; margin-bottom: 8px; }
.field input[type="email"], .field input[type="text"] {
  width: 100%;
  min-height: 48px;
  border: 1px solid var(--line);
  border-radius: var(--r-s);
  padding: 0 14px;
  font: inherit;
  background: #fff;
  color: var(--ink);
  outline: none;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.field input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(26, 75, 224, 0.14); }
.field { margin-bottom: 20px; }
.otp-row { display: flex; gap: 8px; justify-content: space-between; margin-bottom: 20px; }
.otp-row input {
  width: 100%;
  max-width: 52px;
  aspect-ratio: 5 / 6;
  text-align: center;
  font-family: var(--font-mono);
  font-size: 1.4rem;
  font-weight: 600;
  border: 1px solid var(--line);
  border-radius: var(--r-s);
  background: #fff;
  outline: none;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.otp-row input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(26, 75, 224, 0.14); }
.form-error { color: var(--bad); font-size: 0.88rem; min-height: 1.4em; margin: -8px 0 12px; }
.form-note { color: var(--ink-3); font-size: 0.85rem; margin-top: 16px; }
.form-note button { background: none; border: 0; color: var(--accent); font-weight: 600; padding: 0; }

/* ---------- app (learn) ---------- */
.app-main { padding-top: var(--nav-h); min-height: 100svh; }
.dash-head { padding-block: 48px 8px; }
.stat-row { display: flex; gap: 16px; flex-wrap: wrap; margin-top: 24px; }
.stat-chip {
  padding: 14px 20px;
  border-radius: var(--r-m);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--ink-2);
}
.stat-chip strong { color: var(--ink); font-size: 1.05rem; margin-right: 6px; }

.lesson-list { display: flex; flex-direction: column; gap: 10px; }
.lesson-row {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 16px 20px;
  border-radius: var(--r-m);
  background: #fff;
  border: 1px solid var(--line);
  color: var(--ink);
  transition: transform 0.25s var(--ease-out), border-color 0.2s ease;
}
.lesson-row:hover { transform: translateX(4px); border-color: rgba(26, 75, 224, 0.4); }
.lesson-row .n {
  flex: none;
  width: 34px;
  height: 34px;
  border-radius: 10px;
  display: grid;
  place-items: center;
  background: var(--bg-2);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-3);
}
.lesson-row.done .n { background: var(--ok-soft); color: var(--ok); }
.lesson-row .t { flex: 1; min-width: 0; }
.lesson-row .t .title { font-weight: 600; font-size: 0.98rem; }
.lesson-row .t .kind { font-size: 0.8rem; color: var(--ink-3); font-family: var(--font-mono); }
.lesson-row .xp { font-family: var(--font-mono); font-size: 0.78rem; color: var(--ink-3); flex: none; }
.level-label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-3);
  margin: 32px 0 12px;
}
.progressbar { height: 6px; border-radius: 999px; background: var(--bg-2); overflow: hidden; }
.progressbar i { display: block; height: 100%; border-radius: inherit; background: var(--accent); transition: width 0.6s var(--ease-out); }

/* ---------- lesson player ---------- */
.lesson-shell {
  display: grid;
  grid-template-columns: minmax(340px, 5fr) minmax(420px, 7fr);
  gap: 20px;
  align-items: start;
  padding-block: 32px 64px;
}
@media (max-width: 980px) { .lesson-shell { grid-template-columns: 1fr; } }
.teach-panel { padding: 28px; position: sticky; top: calc(var(--nav-h) + 20px); }
@media (max-width: 980px) { .teach-panel { position: static; } }
.teach-panel h1 { font-size: 1.35rem; margin-bottom: 16px; }
.teach-panel p { color: var(--ink-2); font-size: 0.96rem; margin: 0 0 14px; }
.teach-panel .codeblock {
  background: #0f1419;
  color: #e6edf3;
  border-radius: var(--r-s);
  padding: 16px;
  font-family: var(--font-mono);
  font-size: 0.88rem;
  line-height: 1.7;
  overflow-x: auto;
  margin: 0 0 14px;
  white-space: pre;
}
.teach-panel .note {
  border-left: 3px solid var(--accent);
  background: var(--accent-soft);
  padding: 12px 16px;
  border-radius: 0 var(--r-s) var(--r-s) 0;
  color: var(--ink-2);
  font-size: 0.92rem;
  margin: 0 0 14px;
}
.task-line {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  background: var(--accent-soft);
  border: 1px solid rgba(26, 75, 224, 0.25);
  border-radius: var(--r-s);
  padding: 14px 16px;
  font-weight: 500;
  font-size: 0.95rem;
  margin-top: 20px;
}
.strict-flag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--bad);
  background: var(--bad-soft);
  border-radius: var(--r-pill);
  padding: 4px 10px;
  margin-bottom: 12px;
}

.player-panel { overflow: hidden; }
.player-head {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--line);
}
.player-head .file-name { font-family: var(--font-mono); font-size: 0.8rem; color: var(--ink-3); margin-left: 4px; }
.player-head .spacer { flex: 1; }
.code-editor {
  width: 100%;
  min-height: 320px;
  border: 0;
  outline: 0;
  resize: vertical;
  padding: 20px;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--ink);
  background: #fff;
  tab-size: 4;
}
.player-foot {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px;
  border-top: 1px solid var(--line);
  flex-wrap: wrap;
}
.verdict { font-size: 0.92rem; font-weight: 500; min-height: 1.4em; }
.verdict.ok { color: var(--ok); }
.verdict.bad { color: var(--bad); }

/* ---------- misc ---------- */
.page-bg {
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(760px 520px at 82% -10%, rgba(26, 75, 224, 0.07), transparent 60%),
    radial-gradient(680px 500px at -10% 30%, rgba(13, 116, 128, 0.06), transparent 60%),
    var(--bg);
}
.empty-note { color: var(--ink-3); font-size: 0.95rem; }

@media (max-width: 640px) {
  .hero-proof { flex-wrap: wrap; gap: 16px; }
  .hero-actions .btn { flex: 1 1 auto; }
  .otp-row input { max-width: none; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
  *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
}

@media (max-width: 720px) {
  .nav .wrap { gap: 12px; padding-inline: 16px; }
  .nav-links a:not(.btn) { display: none; }
  .nav-links { margin-left: auto; }
}