/* =========================================================
   Python Tutor — Hero landing page
   Dark local-first aesthetic. Amber accent.
   Tokens mirror frontend/base.css so the landing reads as
   the same product as the app.
   ========================================================= */

:root {
  --bg-0: #0c0c0d;
  --bg-1: #141416;
  --bg-2: #1c1c1f;
  --bg-3: #26262a;
  --ink-0: #f4f2ee;
  --ink-1: #d6d3cd;
  --ink-2: #a09b92;
  --ink-3: #6a655d;
  --line-1: rgba(255,255,255,0.06);
  --line-2: rgba(255,255,255,0.10);
  --amber: #e8a13b;
  --amber-soft: #f1b55a;
  --amber-deep: #b87a22;
  --amber-wash: rgba(232,161,59,0.10);
  --leaf: #7aa36b;

  --t-kw: #d49a4b;
  --t-builtin: #c8b88a;
  --t-str: #9ab88d;
  --t-num: #d98f6c;
  --t-com: #6a655d;
  --t-fn: #e8d9a1;

  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Inter, system-ui, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, 'JetBrains Mono', Menlo, Consolas, monospace;

  --r-sm: 6px;
  --r-md: 10px;
  --r-lg: 14px;
  --r-xl: 20px;
  --r-pill: 999px;

  --page-max: 1200px;
  --ease: cubic-bezier(0.2, 0.7, 0.2, 1);
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg-0);
  color: var(--ink-1);
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--amber); text-decoration: none; }
a:hover { color: var(--amber-soft); }
h1, h2, h3, h4, p { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
::selection { background: var(--amber-wash); color: var(--ink-0); }

.skip-link {
  position: absolute; left: -9999px;
}
.skip-link:focus {
  left: 12px; top: 12px;
  background: var(--bg-1); color: var(--ink-0);
  padding: 8px 12px; border-radius: var(--r-sm);
  z-index: 100;
}

/* ============ TOPBAR ============ */
.topbar {
  position: sticky; top: 0; z-index: 40;
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 16px;
  padding: 14px 24px;
  background: color-mix(in oklab, var(--bg-0) 85%, transparent);
  backdrop-filter: saturate(140%) blur(14px);
  -webkit-backdrop-filter: saturate(140%) blur(14px);
  border-bottom: 1px solid var(--line-1);
}
.brand {
  display: inline-flex; align-items: center; gap: 10px;
  color: var(--ink-0); font-weight: 700; letter-spacing: -0.01em;
}
.brand__mark { width: 28px; height: 28px; flex-shrink: 0; }
.brand__name { font-size: 16px; }
.brand__dot { color: var(--amber); }
.topbar__nav { display: none; gap: 8px; justify-self: end; align-items: center; }
.topbar__link {
  color: var(--ink-2); font-size: 14px;
  padding: 8px 12px; border-radius: var(--r-sm);
  transition: color 140ms var(--ease), background 140ms var(--ease);
}
.topbar__link:hover { color: var(--ink-0); background: var(--bg-2); }
.topbar__cta { justify-self: end; }
@media (min-width: 760px) {
  .topbar { padding: 16px 32px; }
  .topbar__nav { display: inline-flex; }
}

/* ============ BUTTONS ============ */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 11px 18px; border-radius: var(--r-md);
  font-weight: 600; font-size: 14.5px; letter-spacing: 0.01em;
  border: 1px solid transparent; cursor: pointer;
  transition: transform 140ms var(--ease), background 140ms var(--ease),
              color 140ms var(--ease), border-color 140ms var(--ease),
              box-shadow 240ms var(--ease);
}
.btn--primary {
  background: var(--amber); color: #1a1206;
  box-shadow: 0 1px 0 rgba(255,255,255,0.18) inset,
              0 10px 30px -12px rgba(232,161,59,0.6);
}
.btn--primary:hover { background: var(--amber-soft); color: #1a1206; transform: translateY(-1px); }
.btn--ghost {
  background: transparent; color: var(--ink-0);
  border-color: var(--line-2);
}
.btn--ghost:hover { background: var(--bg-2); color: var(--ink-0); border-color: var(--line-2); }

/* ============ HERO ============ */
.hero {
  position: relative;
  padding: 64px 24px 56px;
  overflow: hidden;
}
.hero__bg {
  position: absolute; inset: 0; pointer-events: none;
  background:
    radial-gradient(60% 50% at 75% 20%, rgba(232,161,59,0.10), transparent 70%),
    radial-gradient(50% 40% at 10% 80%, rgba(232,161,59,0.06), transparent 70%),
    linear-gradient(180deg, #0a0a0b 0%, var(--bg-0) 60%);
}
.hero__bg::after {
  content: "";
  position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.025) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.025) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(60% 50% at 50% 30%, #000 30%, transparent 80%);
  -webkit-mask-image: radial-gradient(60% 50% at 50% 30%, #000 30%, transparent 80%);
}
.hero__inner {
  position: relative;
  max-width: var(--page-max);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr;
  gap: 48px;
  align-items: center;
}
@media (min-width: 980px) {
  .hero { padding: 96px 32px 88px; }
  .hero__inner { grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr); gap: 56px; }
}
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 6px 12px; border-radius: var(--r-pill);
  background: var(--amber-wash);
  border: 1px solid rgba(232,161,59,0.25);
  color: var(--amber-soft);
  font-size: 12.5px; letter-spacing: 0.02em;
  margin-bottom: 18px;
}
.eyebrow .dot {
  width: 7px; height: 7px; border-radius: 50%;
  background: var(--amber);
  box-shadow: 0 0 0 4px rgba(232,161,59,0.15);
}
.hero__title {
  font-size: clamp(2.2rem, 5.8vw, 4rem);
  line-height: 1.04;
  letter-spacing: -0.02em;
  color: var(--ink-0);
  font-weight: 800;
  margin-bottom: 18px;
}
.hero__title .accent { color: var(--amber); }
.hero__lede {
  font-size: clamp(1.05rem, 1.5vw, 1.2rem);
  color: var(--ink-1);
  max-width: 56ch;
  margin-bottom: 28px;
}
.hero__lede strong { color: var(--ink-0); font-weight: 600; }
.hero__cta { display: flex; gap: 12px; flex-wrap: wrap; margin-bottom: 22px; }
.hero__chips {
  display: flex; flex-wrap: wrap; gap: 8px;
  font-size: 13px; color: var(--ink-2);
}
.hero__chips li {
  padding: 4px 10px; border-radius: var(--r-pill);
  background: var(--bg-1);
  border: 1px solid var(--line-1);
}

/* ============ MOCK APP ============ */
.hero__mock { perspective: 1400px; }
.mock {
  background: var(--bg-1);
  border: 1px solid var(--line-2);
  border-radius: var(--r-lg);
  box-shadow:
    0 1px 0 rgba(255,255,255,0.04) inset,
    0 30px 80px -30px rgba(0,0,0,0.75),
    0 0 0 1px rgba(232,161,59,0.05);
  overflow: hidden;
  transform: rotateX(2deg);
}
.mock__chrome {
  display: flex; align-items: center; gap: 8px;
  padding: 10px 14px;
  background: linear-gradient(180deg, #18181a, #131315);
  border-bottom: 1px solid var(--line-1);
}
.mock__dot { width: 10px; height: 10px; border-radius: 50%; }
.mock__dot--r { background: #ef6a5a; }
.mock__dot--y { background: #efc05a; }
.mock__dot--g { background: #7aa36b; }
.mock__url {
  margin-left: 10px; font-family: var(--font-mono);
  font-size: 12px; color: var(--ink-3);
}
.mock__body {
  display: grid;
  grid-template-columns: 150px 1fr;
  min-height: 360px;
}
.mock__side {
  padding: 16px 14px;
  background: #101012;
  border-right: 1px solid var(--line-1);
}
.mock__side-title {
  text-transform: uppercase;
  font-size: 10.5px; letter-spacing: 0.12em;
  color: var(--ink-3);
  margin-bottom: 10px;
}
.mock__list li {
  font-size: 13px; color: var(--ink-2);
  padding: 7px 9px; border-radius: var(--r-sm);
  margin-bottom: 2px;
}
.mock__list li.is-active {
  background: var(--amber-wash);
  color: var(--amber-soft);
  border: 1px solid rgba(232,161,59,0.22);
}
.mock__list li.is-muted { color: var(--ink-3); font-style: italic; }
.mock__main { padding: 18px 18px 22px; min-width: 0; }
.mock__h {
  font-size: 18px; color: var(--ink-0); font-weight: 700;
  margin-bottom: 6px; letter-spacing: -0.01em;
}
.mock__p { font-size: 13.5px; color: var(--ink-2); margin-bottom: 14px; }
.mock__lab {
  border: 1px solid var(--line-1);
  border-radius: var(--r-md);
  background: var(--bg-3);
  overflow: hidden;
}
.mock__lab-head {
  display: flex; justify-content: space-between; align-items: center;
  padding: 8px 12px;
  background: #1a1a1c;
  border-bottom: 1px solid var(--line-1);
  font-size: 11.5px;
}
.mock__tag {
  color: var(--ink-3); text-transform: uppercase; letter-spacing: 0.1em;
}
.mock__run { color: var(--amber); font-weight: 600; }
.mock__code {
  margin: 0;
  padding: 12px 14px;
  font-family: var(--font-mono);
  font-size: 13.5px;
  line-height: 1.65;
  color: var(--ink-1);
  white-space: pre-wrap;
  word-break: break-word;
  overflow-x: auto;
}
.mock__code .t-com { color: var(--t-com); font-style: italic; }
.mock__code .t-kw { color: var(--t-kw); }
.mock__code .t-fn { color: var(--t-fn); }
.mock__code .t-str { color: var(--t-str); }
.mock__code .t-num { color: var(--t-num); }
.mock__out {
  display: flex; align-items: center; gap: 12px;
  padding: 10px 14px;
  background: rgba(122,163,107,0.08);
  border-top: 1px solid rgba(122,163,107,0.18);
  font-family: var(--font-mono);
  font-size: 13px;
}
.mock__ok { color: var(--leaf); font-weight: 600; }
.mock__out code { color: var(--ink-1); }
.mock__chat {
  margin-top: 14px;
  background: var(--bg-2);
  border: 1px solid var(--line-2);
  border-radius: var(--r-md);
  box-shadow: 0 18px 40px -18px rgba(0,0,0,0.7);
  overflow: hidden;
}
.mock__chat-head {
  display: flex; justify-content: space-between; align-items: center;
  padding: 8px 12px;
  background: #19191c;
  border-bottom: 1px solid var(--line-1);
  font-size: 12.5px;
}
.mock__chat-title { color: var(--ink-0); font-weight: 600; }
.mock__chat-x { color: var(--ink-3); }
.mock__chat-body { padding: 10px 12px 12px; display: grid; gap: 8px; }
.mock__bubble {
  font-size: 12.5px; line-height: 1.5;
  padding: 8px 10px; border-radius: 10px;
}
.mock__bubble code {
  font-family: var(--font-mono);
  background: rgba(255,255,255,0.06);
  padding: 0 4px; border-radius: 4px; font-size: 11.5px;
}
.mock__bubble--you {
  background: var(--bg-3); color: var(--ink-1);
  justify-self: end; max-width: 80%;
}
.mock__bubble--bot {
  background: var(--amber-wash);
  color: var(--ink-0);
  border: 1px solid rgba(232,161,59,0.18);
  max-width: 92%;
}
.mock__cite {
  display: inline-block; margin-top: 4px;
  color: var(--amber); font-size: 11.5px;
}

@media (max-width: 520px) {
  .mock__body { grid-template-columns: 1fr; }
  .mock__side { display: none; }
}

/* ============ SECTION SHELL ============ */
.section__title {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  letter-spacing: -0.015em;
  color: var(--ink-0);
  font-weight: 700;
  margin-bottom: 6px;
}
.section__lede {
  color: var(--ink-2);
  font-size: 1.05rem;
  margin-bottom: 32px;
  max-width: 56ch;
}

/* ============ ROWS (useful / private / credible) ============ */
.rows { padding: 72px 24px; border-top: 1px solid var(--line-1); }
.rows__inner { max-width: var(--page-max); margin: 0 auto; }
.rows__list { display: grid; gap: 16px; margin-top: 28px; }
@media (min-width: 820px) {
  .rows__list { grid-template-columns: repeat(3, 1fr); }
}
.row {
  background: var(--bg-1);
  border: 1px solid var(--line-1);
  border-radius: var(--r-lg);
  padding: 22px 22px 24px;
  display: grid;
  grid-template-columns: 44px 1fr;
  gap: 14px;
  align-items: start;
  transition: border-color 240ms var(--ease), transform 240ms var(--ease);
}
.row:hover { border-color: rgba(232,161,59,0.25); transform: translateY(-2px); }
.row__icon {
  width: 44px; height: 44px;
  display: grid; place-items: center;
  background: var(--amber-wash);
  color: var(--amber-soft);
  border-radius: var(--r-md);
  border: 1px solid rgba(232,161,59,0.22);
}
.row__text h3 {
  font-size: 1.05rem;
  color: var(--ink-0);
  font-weight: 700;
  margin-bottom: 4px;
}
.row__text p {
  font-size: 0.95rem;
  color: var(--ink-2);
  line-height: 1.55;
}
.row__text em { color: var(--ink-1); font-style: italic; }
.row__text strong { color: var(--ink-0); }

/* ============ LOOP ============ */
.loop {
  padding: 72px 24px;
  border-top: 1px solid var(--line-1);
  background:
    radial-gradient(70% 50% at 50% 0%, rgba(232,161,59,0.05), transparent 70%),
    var(--bg-0);
}
.loop__inner { max-width: var(--page-max); margin: 0 auto; }
.loop__steps {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
  margin-top: 18px;
}
@media (min-width: 820px) {
  .loop__steps {
    grid-template-columns: 1fr auto 1fr auto 1fr auto 1fr;
    align-items: stretch;
  }
}
.step {
  display: grid;
  grid-template-rows: auto auto 1fr;
  gap: 6px;
  padding: 20px;
  background: var(--bg-1);
  border: 1px solid var(--line-1);
  border-radius: var(--r-lg);
}
.step__num {
  width: 28px; height: 28px;
  display: grid; place-items: center;
  border-radius: 50%;
  background: var(--amber);
  color: #1a1206;
  font-weight: 800; font-size: 13px;
}
.step__label {
  color: var(--ink-0); font-weight: 700; font-size: 1.02rem;
}
.step__sub { color: var(--ink-2); font-size: 0.9rem; }
.step__arrow {
  display: none;
  align-self: center; justify-self: center;
  color: var(--ink-3); font-size: 22px;
}
@media (min-width: 820px) { .step__arrow { display: block; } }

/* ============ SCREENS ============ */
.screens {
  padding: 72px 24px;
  border-top: 1px solid var(--line-1);
}
.screens__inner { max-width: var(--page-max); margin: 0 auto; }
.screens__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 18px;
}
@media (min-width: 700px) {
  .screens__grid { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 1024px) {
  .screens__grid { grid-template-columns: repeat(3, 1fr); }
}
.shot {
  margin: 0;
  background: var(--bg-1);
  border: 1px solid var(--line-1);
  border-radius: var(--r-lg);
  overflow: hidden;
  transition: border-color 240ms var(--ease), transform 240ms var(--ease);
}
.shot:hover { border-color: rgba(232,161,59,0.30); transform: translateY(-2px); }
.shot img {
  width: 100%; aspect-ratio: 16/10; object-fit: cover;
  border-bottom: 1px solid var(--line-1);
  background: var(--bg-2);
}
.shot figcaption {
  padding: 12px 14px;
  font-size: 0.92rem;
  color: var(--ink-2);
}
.shot figcaption strong { color: var(--ink-0); font-weight: 600; }

/* ============ START ============ */
.start {
  padding: 72px 24px 96px;
  border-top: 1px solid var(--line-1);
  background:
    radial-gradient(50% 60% at 50% 100%, rgba(232,161,59,0.08), transparent 70%),
    var(--bg-0);
}
.start__inner { max-width: 880px; margin: 0 auto; text-align: left; }
.start__code {
  margin-top: 8px;
  background: var(--bg-3);
  border: 1px solid var(--line-2);
  border-radius: var(--r-md);
  overflow: hidden;
}
.start__code pre {
  margin: 0;
  padding: 18px 20px;
  font-family: var(--font-mono);
  font-size: 14px;
  line-height: 1.7;
  color: var(--ink-1);
  overflow-x: auto;
}
.start__code .t-com { color: var(--t-com); font-style: italic; }
.start__code .t-kw { color: var(--t-kw); }
.start__note {
  margin-top: 18px;
  color: var(--ink-2);
  font-size: 0.95rem;
}
.start__note code {
  font-family: var(--font-mono);
  background: var(--bg-2);
  padding: 1px 6px; border-radius: 4px;
  color: var(--ink-1); font-size: 0.9em;
}
.start__note strong { color: var(--ink-0); }
.start__cta {
  margin-top: 24px;
  display: flex; gap: 12px; flex-wrap: wrap;
}

/* numbered step cards */
.start__steps {
  margin-top: 28px;
  display: grid;
  gap: 18px;
}
.start__step {
  background: var(--bg-1);
  border: 1px solid var(--line-1);
  border-radius: var(--r-lg);
  padding: 20px 22px 22px;
}
.start__step-head {
  display: flex; align-items: center; gap: 12px;
  margin-bottom: 6px;
}
.start__step-num {
  width: 28px; height: 28px;
  display: grid; place-items: center;
  border-radius: 50%;
  background: var(--amber);
  color: #1a1206;
  font-weight: 800; font-size: 13px;
  flex-shrink: 0;
}
.start__step-title {
  font-size: 1.05rem;
  color: var(--ink-0);
  font-weight: 700;
  letter-spacing: -0.01em;
}
.start__step-sub {
  color: var(--ink-2);
  font-size: 0.95rem;
  margin: 4px 0 12px;
}
.start__step-sub code {
  font-family: var(--font-mono);
  background: var(--bg-2);
  padding: 1px 6px; border-radius: 4px;
  color: var(--ink-1); font-size: 0.9em;
}
.start__step-sub strong { color: var(--ink-0); }
.start__step-sub--muted { color: var(--ink-3); margin-top: 10px; margin-bottom: 0; }

/* per-OS label above paired code blocks (macOS/Linux vs Windows) */
.start__os-label {
  margin-top: 14px;
  margin-bottom: 6px;
  font-family: var(--font-sans);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ink-2);
}
.start__os-label:first-child { margin-top: 0; }

/* code block with copy button */
.start__code--with-copy {
  position: relative;
}
.copy-btn {
  position: absolute;
  top: 10px; right: 10px;
  padding: 6px 12px;
  font-size: 12px;
  font-family: var(--font-sans);
  font-weight: 600;
  color: var(--ink-1);
  background: var(--bg-1);
  border: 1px solid var(--line-2);
  border-radius: var(--r-sm);
  cursor: pointer;
  transition: background 140ms var(--ease), color 140ms var(--ease), border-color 140ms var(--ease);
}
.copy-btn:hover {
  background: var(--bg-2); color: var(--ink-0);
  border-color: rgba(232,161,59,0.3);
}
.copy-btn.is-copied {
  background: var(--amber-wash);
  color: var(--amber-soft);
  border-color: rgba(232,161,59,0.4);
}

/* more / details disclosure */
.start__more {
  margin-top: 22px;
  border: 1px solid var(--line-1);
  border-radius: var(--r-md);
  background: var(--bg-1);
  padding: 14px 18px;
}
.start__more > summary {
  cursor: pointer;
  color: var(--ink-0);
  font-weight: 600;
  font-size: 0.95rem;
  list-style: none;
}
.start__more > summary::-webkit-details-marker { display: none; }
.start__more > summary::before {
  content: "▸ ";
  color: var(--amber);
  display: inline-block;
  margin-right: 6px;
  transition: transform 140ms var(--ease);
}
.start__more[open] > summary::before { content: "▾ "; }
.start__more > .start__code { margin-top: 12px; }

/* links row beneath the steps */
.start__links {
  margin-top: 24px;
  display: flex; gap: 12px; flex-wrap: wrap;
}

/* ============ FOOT ============ */
.foot {
  border-top: 1px solid var(--line-1);
  background: #0a0a0b;
  padding: 32px 24px 40px;
}
.foot__inner {
  max-width: var(--page-max);
  margin: 0 auto;
  display: grid;
  gap: 18px;
}
@media (min-width: 760px) {
  .foot__inner {
    grid-template-columns: auto 1fr auto;
    align-items: center;
  }
}
.foot__brand {
  display: inline-flex; align-items: center; gap: 10px;
  color: var(--ink-1); font-weight: 600;
}
.foot__nav {
  display: flex; gap: 18px; flex-wrap: wrap;
}
.foot__nav a { color: var(--ink-2); font-size: 0.92rem; }
.foot__nav a:hover { color: var(--ink-0); }
.foot__note {
  color: var(--ink-3);
  font-size: 0.85rem;
}
.foot__note a { color: var(--ink-2); border-bottom: 1px dotted var(--line-2); }
.foot__note a:hover { color: var(--ink-0); }