@font-face {
  font-family: 'Space Grotesk';
  src: url('fonts/space-grotesk.woff2') format('woff2');
  font-weight: 300 700;
  font-display: swap;
}
@font-face {
  font-family: 'Inter';
  src: url('fonts/inter.woff2') format('woff2');
  font-weight: 100 900;
  font-display: swap;
}

:root {
  --bg: #070b18;
  --bg-2: #0c1328;
  --panel: rgba(255, 255, 255, 0.04);
  --line: rgba(255, 255, 255, 0.09);
  --ink: #eaf0ff;
  --muted: #a3afd1;
  --cyan: #34e7e4;
  --violet: #8e6cff;
  --amber: #ffb648;
  --grad: linear-gradient(100deg, var(--cyan), var(--violet));
  --display: 'Space Grotesk', ui-sans-serif, system-ui, sans-serif;
  --body: 'Inter', ui-sans-serif, system-ui, -apple-system, 'Segoe UI', sans-serif;
  --radius: 18px;
  color-scheme: dark;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { scroll-behavior: smooth; scroll-padding-top: 80px; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 17px/1.6 var(--body);
  -webkit-font-smoothing: antialiased;
}
h1, h2, h3 { font-family: var(--display); line-height: 1.08; letter-spacing: -0.02em; margin: 0; }
p { margin: 0; }
a { color: var(--cyan); }
:focus-visible { outline: 2px solid var(--amber); outline-offset: 3px; border-radius: 6px; }

.skip { position: absolute; left: -999px; top: 8px; background: var(--amber); color: #111; padding: 8px 14px; border-radius: 8px; z-index: 50; }
.skip:focus { left: 12px; }

.wrap { max-width: 1120px; margin: 0 auto; padding: 0 24px; }
.grad { background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; }

/* Nav */
.nav {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 24px;
  background: rgba(7, 11, 24, 0.6);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; color: var(--ink); text-decoration: none; font: 600 22px/1 var(--display); letter-spacing: -0.03em; }
.brand-mark { width: 30px; height: 30px; }
.nav nav { display: flex; align-items: center; gap: 22px; }
.nav nav a { color: var(--muted); text-decoration: none; font-size: 15px; }
.nav nav a:hover { color: var(--ink); }
.nav nav .nav-cta { color: var(--ink); border: 1px solid var(--line); padding: 8px 14px; border-radius: 999px; background: var(--panel); }
.nav nav .nav-cta:hover { border-color: var(--cyan); }

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 50px;
  padding: 0 24px;
  border-radius: 999px;
  font: 600 16px/1 var(--body);
  text-decoration: none;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.2s ease, background 0.2s ease;
}
.btn-primary { background: var(--grad); color: #06101c; box-shadow: 0 10px 40px -10px rgba(52, 231, 228, 0.55); }
.btn-primary:hover { transform: translateY(-1px); box-shadow: 0 14px 44px -8px rgba(142, 108, 255, 0.6); }
.btn-primary:disabled { opacity: 0.6; cursor: progress; transform: none; }
.btn-ghost { color: var(--ink); border-color: var(--line); background: var(--panel); }
.btn-ghost:hover { border-color: var(--cyan); }
.btn-block { width: 100%; }

/* Hero */
.hero {
  position: relative;
  min-height: 100vh;
  min-height: 100svh;
  display: flex;
  align-items: center;
  overflow: hidden;
  background:
    radial-gradient(900px 500px at 78% 18%, rgba(142, 108, 255, 0.22), transparent 60%),
    radial-gradient(700px 480px at 12% 85%, rgba(52, 231, 228, 0.16), transparent 60%),
    var(--bg);
}
.circuit { position: absolute; inset: 0; width: 100%; height: 100%; }
.hero::after { content: ''; position: absolute; inset: auto 0 0 0; height: 160px; background: linear-gradient(transparent, var(--bg)); pointer-events: none; }
.hero-inner { position: relative; z-index: 1; max-width: 1120px; margin: 0 auto; padding: 120px 24px 80px; width: 100%; }
.eyebrow { display: inline-flex; align-items: center; gap: 10px; font-size: 14px; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); border: 1px solid var(--line); background: rgba(7, 11, 24, 0.55); padding: 7px 14px; border-radius: 999px; }
.dot { width: 8px; height: 8px; border-radius: 50%; background: var(--amber); box-shadow: 0 0 12px var(--amber); animation: pulse 2.4s ease-in-out infinite; }
@keyframes pulse { 50% { opacity: 0.35; } }
.hero h1 { font-size: clamp(44px, 8.4vw, 104px); font-weight: 700; margin: 26px 0 24px; max-width: 12ch; }
.hero h1 em { font-style: normal; background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; }
.lede { font-size: clamp(18px, 2.1vw, 22px); color: var(--muted); max-width: 40ch; }
.lede strong { color: var(--ink); font-weight: 600; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 36px; }

/* Sections */
section:not(.hero) { padding: 110px 0; }
h2 { font-size: clamp(34px, 5vw, 60px); font-weight: 700; }
.sub { color: var(--muted); font-size: 19px; max-width: 58ch; margin-top: 22px; }
.fineprint { color: var(--muted); font-size: 13px; margin-top: 16px; }
.fineprint a { color: var(--muted); }

.compare { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; margin-top: 56px; }
.compare-col { border: 1px solid var(--line); border-radius: var(--radius); padding: 28px; background: var(--panel); }
.compare-col h3 { font-size: 20px; margin-bottom: 16px; color: var(--muted); }
.compare-col ul { list-style: none; margin: 0; padding: 0; }
.compare-col li { padding: 12px 0 12px 30px; border-top: 1px solid var(--line); position: relative; color: var(--muted); }
.compare-col li::before { content: '–'; position: absolute; left: 4px; color: var(--muted); }
.compare-col-us { border-color: rgba(52, 231, 228, 0.35); background: linear-gradient(160deg, rgba(52, 231, 228, 0.09), rgba(142, 108, 255, 0.09)); }
.compare-col-us h3 { color: var(--ink); }
.compare-col-us li { color: var(--ink); }
.compare-col-us li::before { content: '✓'; color: var(--cyan); }

/* Demo */
.demo { background: linear-gradient(180deg, var(--bg), var(--bg-2) 30%, var(--bg-2) 70%, var(--bg)); }
.demo-grid { display: grid; grid-template-columns: minmax(0, 5fr) minmax(0, 7fr); gap: 24px; margin-top: 52px; align-items: start; }
.topics { display: grid; gap: 12px; }
.topic {
  text-align: left;
  font: inherit;
  color: var(--ink);
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 18px 20px;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s, transform 0.15s;
}
.topic:hover { border-color: rgba(52, 231, 228, 0.5); transform: translateX(3px); }
.topic[aria-selected='true'] { border-color: var(--cyan); background: linear-gradient(120deg, rgba(52, 231, 228, 0.12), rgba(142, 108, 255, 0.12)); }
.topic-tag { display: block; font-size: 12px; letter-spacing: 0.1em; text-transform: uppercase; color: var(--cyan); margin-bottom: 4px; }
.topic-q { display: block; font-family: var(--display); font-size: 19px; font-weight: 600; }

.chat { border: 1px solid var(--line); border-radius: var(--radius); background: rgba(5, 8, 18, 0.75); box-shadow: 0 30px 80px -30px rgba(142, 108, 255, 0.45); overflow: hidden; min-height: 520px; display: flex; flex-direction: column; }
.chat-head { display: flex; align-items: center; gap: 12px; padding: 14px 18px; border-bottom: 1px solid var(--line); font-size: 13px; color: var(--muted); }
.chat-dots { display: flex; gap: 6px; }
.chat-dots i { width: 10px; height: 10px; border-radius: 50%; background: rgba(255, 255, 255, 0.14); }
.replay { margin-left: auto; font: inherit; font-size: 13px; color: var(--ink); background: none; border: 1px solid var(--line); border-radius: 999px; padding: 5px 12px; cursor: pointer; }
.replay:hover { border-color: var(--cyan); }
.chat-log { list-style: none; margin: 0; padding: 22px 18px 8px; display: flex; flex-direction: column; gap: 12px; flex: 1; }
.msg { max-width: 85%; padding: 12px 16px; border-radius: 16px; animation: rise 0.35s ease both; }
.msg-learner { align-self: flex-end; background: rgba(255, 255, 255, 0.08); border-bottom-right-radius: 4px; }
.msg-guide { align-self: flex-start; background: linear-gradient(135deg, rgba(52, 231, 228, 0.16), rgba(142, 108, 255, 0.16)); border: 1px solid rgba(52, 231, 228, 0.22); border-bottom-left-radius: 4px; }
.msg-who { display: block; font-size: 11px; letter-spacing: 0.1em; text-transform: uppercase; color: var(--muted); margin-bottom: 2px; }
.msg-guide .msg-who { color: var(--cyan); }
.msg-aha { border-color: rgba(255, 182, 72, 0.6); background: linear-gradient(135deg, rgba(255, 182, 72, 0.18), rgba(142, 108, 255, 0.14)); }
.msg-aha .msg-who { color: var(--amber); }
.typing { align-self: flex-start; display: flex; gap: 5px; padding: 14px 16px; border-radius: 16px; background: rgba(255, 255, 255, 0.05); }
.typing i { width: 7px; height: 7px; border-radius: 50%; background: var(--muted); animation: blink 1s infinite ease-in-out; }
.typing i:nth-child(2) { animation-delay: 0.15s; }
.typing i:nth-child(3) { animation-delay: 0.3s; }
@keyframes blink { 0%, 80%, 100% { opacity: 0.25; } 40% { opacity: 1; } }
@keyframes rise { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }
.chat-moment { margin: 6px 18px 20px; padding: 12px 16px; border-radius: 12px; color: var(--amber); font-family: var(--display); font-weight: 600; font-size: 18px; border: 1px dashed rgba(255, 182, 72, 0.45); animation: rise 0.5s ease both; }

/* Approach */
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin-top: 52px; }
.card { position: relative; border: 1px solid var(--line); border-radius: var(--radius); padding: 30px 28px; background: var(--panel); overflow: hidden; }
.card::before { content: ''; position: absolute; inset: 0 0 auto 0; height: 3px; background: var(--grad); opacity: 0.8; }
.card-num { font: 700 15px/1 var(--display); color: var(--cyan); }
.card h3 { font-size: 26px; margin: 18px 0 12px; }
.card p { color: var(--muted); }

.domains { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; margin-top: 18px; }
.domain { border: 1px solid var(--line); border-radius: var(--radius); padding: 26px 24px; background: linear-gradient(180deg, rgba(142, 108, 255, 0.08), transparent); }
.domain svg { width: 40px; height: 40px; color: var(--cyan); }
.domain h3 { font-size: 21px; margin: 14px 0 6px; }
.domain p { color: var(--muted); font-size: 15px; }

/* Briefing */
.briefing { background: radial-gradient(800px 500px at 15% 50%, rgba(142, 108, 255, 0.18), transparent 60%), var(--bg); }
.briefing-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 56px; align-items: start; }
.form { border: 1px solid var(--line); border-radius: var(--radius); background: rgba(5, 8, 18, 0.7); padding: 28px; }
.field { margin-bottom: 16px; }
.field label { display: block; font-size: 14px; font-weight: 600; margin-bottom: 6px; }
.opt { color: var(--muted); font-weight: 400; }
.field input, .field select, .field textarea {
  width: 100%;
  font: inherit;
  font-size: 16px;
  color: var(--ink);
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.18);
  border-radius: 10px;
  padding: 12px 14px;
}
.field select option { background: var(--bg-2); }
.field input:focus, .field select:focus, .field textarea:focus { outline: none; border-color: var(--cyan); box-shadow: 0 0 0 3px rgba(52, 231, 228, 0.2); }
.field input[aria-invalid='true'] { border-color: #ff7a8a; }
.hp { position: absolute; left: -9999px; width: 1px; height: 1px; overflow: hidden; }
.form-status { margin-top: 14px; font-weight: 600; min-height: 1.6em; }
.form-status.ok { color: var(--cyan); }
.form-status.err { color: #ff8f9c; }

/* Footer */
.footer { border-top: 1px solid var(--line); padding: 32px 0 40px; color: var(--muted); font-size: 14px; }
.footer-inner { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 12px; }
.footer a { color: var(--muted); }
.footer a:hover { color: var(--ink); }

/* Home page: the call-out into the lesson */
.try-callout { margin-top: 28px; display: flex; flex-wrap: wrap; gap: 18px; align-items: center; justify-content: space-between; padding: 24px 28px; border-radius: var(--radius); border: 1px solid rgba(255, 182, 72, 0.45); background: linear-gradient(130deg, rgba(255, 182, 72, 0.12), rgba(142, 108, 255, 0.12)); }
.try-callout h3 { font-size: 24px; }
.try-callout p { color: var(--muted); margin-top: 6px; }

/* Privacy page */
.doc { max-width: 720px; margin: 0 auto; padding: 140px 24px 80px; }
.doc h1 { font-size: clamp(36px, 6vw, 56px); margin-bottom: 12px; }
.doc h2 { font-size: 24px; margin: 36px 0 10px; }
.doc p, .doc li { color: var(--muted); }
.doc p + p { margin-top: 12px; }

@media (max-width: 900px) {
  .demo-grid, .briefing-grid { grid-template-columns: 1fr; }
  .cards { grid-template-columns: 1fr; }
  .domains { grid-template-columns: 1fr 1fr; }
  .topics { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 620px) {
  .nav nav a:not(.nav-cta) { display: none; }
  .compare { grid-template-columns: 1fr; }
  .topics { grid-template-columns: 1fr; }
  .topic-q { font-size: 17px; }
  .domains { grid-template-columns: 1fr; }
  .chat { min-height: 460px; }
  .msg { max-width: 92%; }
  section:not(.hero) { padding: 80px 0; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
}