:root {
  color-scheme: light;
  --ink: #0f1726;
  --ink-soft: #4b586f;
  --ink-faint: #74809a;
  --paper: #f6f8fc;
  --card: #ffffff;
  --line: #e2e8f3;
  --sky-1: #081c38;
  --sky-2: #10294d;
  --sky-3: #1c4478;
  --accent: #ff6b35;
  --accent-soft: #ffb347;
  --accent-ink: #c1471a;
  --upper: #2f6fed;
  --lower: #0e9f6e;
  --prosthetic: #8b30e0;
  --foundation: #b45309;
  --done: #0e9f6e;
  --radius: 16px;
  --shadow-sm: 0 1px 2px rgba(15, 23, 38, 0.05), 0 2px 8px rgba(15, 23, 38, 0.04);
  --shadow-lg: 0 6px 16px rgba(15, 23, 38, 0.08), 0 20px 44px rgba(15, 23, 38, 0.12);
  --font-display: "Sora", "Avenir Next", system-ui, sans-serif;
  --font-body: "Inter", "Segoe UI", system-ui, -apple-system, sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  line-height: 1.65;
  font-family: var(--font-body);
  font-size: 16px;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3 {
  font-family: var(--font-display);
  line-height: 1.14;
  letter-spacing: -0.022em;
  margin: 0 0 0.5rem;
}
p { margin: 0 0 0.75rem; }
a { color: inherit; }

section[id] { scroll-margin-top: 5rem; }

::selection { background: rgba(255, 107, 53, 0.25); }

.skip-link {
  position: absolute; left: -999px; top: 0;
  background: var(--accent); color: #fff;
  padding: 0.65rem 1.15rem; border-radius: 0 0 10px 0;
  z-index: 100; font-weight: 700; text-decoration: none;
}
.skip-link:focus { left: 0; }

:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 3px;
  border-radius: 6px;
}

/* ─── Header ─────────────────────────────────────────── */
.site-header {
  display: flex; align-items: center; justify-content: space-between; gap: 1rem;
  padding: 0.85rem clamp(1rem, 4vw, 3rem);
  background: rgba(8, 28, 56, 0.9);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  color: #eaf1ff;
  position: sticky; top: 0; z-index: 50;
}
.header-side {
  display: flex; align-items: center; gap: clamp(0.6rem, 2vw, 1.1rem);
  flex-wrap: wrap; justify-content: center;
}
.brand {
  display: inline-flex; align-items: center; gap: 0.6rem;
  text-decoration: none; font-family: var(--font-display);
  font-size: 1.12rem; font-weight: 600; letter-spacing: -0.01em;
}
.brand strong { color: var(--accent); font-weight: 800; }
.brand-mark {
  width: 28px; height: 28px; color: var(--accent);
  filter: drop-shadow(0 2px 6px rgba(255, 107, 53, 0.45));
}
.nav-list { display: flex; gap: clamp(0.35rem, 1.5vw, 0.6rem); list-style: none; margin: 0; padding: 0; flex-wrap: wrap; justify-content: center; }
.nav-list a {
  display: inline-block; text-decoration: none; font-weight: 600; font-size: 0.92rem;
  color: rgba(234, 241, 255, 0.82); padding: 0.45rem 0.85rem; border-radius: 999px;
  transition: color 0.15s ease, background 0.15s ease;
}
.nav-list a:hover { color: #fff; background: rgba(255, 255, 255, 0.1); }

/* ─── Language picker ────────────────────────────────── */
.lang-picker {
  display: inline-flex; align-items: center; gap: 2px;
  border: 1px solid rgba(168, 192, 230, 0.35);
  border-radius: 999px; padding: 3px;
  background: rgba(255, 255, 255, 0.06);
}
.lang-btn {
  border: none; background: transparent; cursor: pointer;
  font-family: var(--font-display); font-weight: 700; font-size: 0.78rem;
  letter-spacing: 0.08em;
  color: rgba(234, 241, 255, 0.72);
  padding: 0.32rem 0.78rem; border-radius: 999px;
  transition: color 0.15s ease, background 0.15s ease, box-shadow 0.15s ease;
}
.lang-btn:hover { color: #fff; background: rgba(255, 255, 255, 0.1); }
.lang-btn.is-active {
  background: linear-gradient(115deg, var(--accent), #ff8a4d);
  color: #fff;
  box-shadow: 0 3px 10px rgba(255, 107, 53, 0.45);
}

/* ─── Hero ───────────────────────────────────────────── */
.hero {
  position: relative;
  overflow: hidden;
  background:
    radial-gradient(58rem 30rem at 82% -12%, rgba(60, 118, 200, 0.4), transparent 62%),
    radial-gradient(44rem 26rem at 8% 108%, rgba(255, 107, 53, 0.16), transparent 58%),
    linear-gradient(163deg, var(--sky-1) 0%, var(--sky-2) 52%, var(--sky-3) 100%);
  color: #f2f6ff;
  padding: clamp(3.5rem, 9vw, 7rem) clamp(1rem, 5vw, 4rem) clamp(4.5rem, 9vw, 7.5rem);
}
.hero::before {
  content: "";
  position: absolute; inset: 0;
  background-image:
    radial-gradient(1.5px 1.5px at 12% 22%, rgba(255,255,255,0.5), transparent 100%),
    radial-gradient(1px 1px at 28% 9%, rgba(255,255,255,0.4), transparent 100%),
    radial-gradient(1.5px 1.5px at 44% 30%, rgba(255,255,255,0.35), transparent 100%),
    radial-gradient(1px 1px at 61% 12%, rgba(255,255,255,0.45), transparent 100%),
    radial-gradient(1.5px 1.5px at 75% 26%, rgba(255,255,255,0.4), transparent 100%),
    radial-gradient(1px 1px at 88% 8%, rgba(255,255,255,0.5), transparent 100%),
    radial-gradient(1px 1px at 94% 38%, rgba(255,255,255,0.3), transparent 100%);
  pointer-events: none;
}
.hero-inner { position: relative; max-width: 72rem; margin: 0 auto; }
.hero-kicker {
  display: inline-flex; align-items: center; gap: 0.6rem;
  text-transform: uppercase; letter-spacing: 0.2em; font-size: 0.74rem;
  color: #a8c0e6; font-weight: 700;
  border: 1px solid rgba(168, 192, 230, 0.35);
  padding: 0.42rem 0.95rem; border-radius: 999px;
  background: rgba(255, 255, 255, 0.05);
  margin-bottom: 1.4rem;
}
.hero h1 {
  font-size: clamp(2.3rem, 5.8vw, 4.1rem);
  font-weight: 800;
  max-width: 19ch;
  margin-bottom: 1.1rem;
}
.hero-accent {
  background: linear-gradient(92deg, var(--accent) 5%, var(--accent-soft) 90%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: transparent;
}
.hero-lead { max-width: 56ch; font-size: clamp(1.02rem, 1.6vw, 1.14rem); color: #c9d8f0; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 0.85rem; margin: 1.8rem 0 2.6rem; }

.btn {
  display: inline-block; padding: 0.85rem 1.65rem; border-radius: 999px; text-decoration: none;
  font-family: var(--font-display); font-weight: 700; font-size: 0.96rem; letter-spacing: 0.01em;
  border: 2px solid transparent;
  transition: transform 0.18s ease, background 0.18s ease, border-color 0.18s ease, box-shadow 0.18s ease;
}
.btn:hover { transform: translateY(-2px); }
.btn:active { transform: translateY(0); }
.btn-primary {
  background: linear-gradient(115deg, var(--accent), #ff8a4d);
  color: #fff;
  box-shadow: 0 10px 26px rgba(255, 107, 53, 0.38);
}
.btn-primary:hover { box-shadow: 0 14px 32px rgba(255, 107, 53, 0.5); }
.btn-ghost { border-color: rgba(168, 192, 230, 0.55); color: #eaf1ff; }
.btn-ghost:hover { border-color: #fff; background: rgba(255, 255, 255, 0.08); }

.hero-stats {
  display: flex; flex-wrap: wrap; gap: clamp(1.25rem, 4vw, 2.5rem); margin: 0;
}
.hero-stats > div {
  padding: 0.9rem 1.35rem;
  border: 1px solid rgba(168, 192, 230, 0.22);
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.05);
  -webkit-backdrop-filter: blur(6px);
  backdrop-filter: blur(6px);
  min-width: 9.5rem;
}
.hero-stats dt {
  font-family: var(--font-display); font-size: 2.05rem; font-weight: 800;
  background: linear-gradient(92deg, var(--accent), var(--accent-soft));
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: transparent;
  line-height: 1.15;
}
.hero-stats dd { margin: 0; color: #b9cbe8; font-size: 0.86rem; font-weight: 500; }

.hero-ridge {
  position: absolute; left: 0; right: 0; bottom: -1px;
  width: 100%; height: clamp(38px, 6vw, 90px);
  color: var(--paper);
  display: block;
}

/* ─── Safety note ────────────────────────────────────── */
.safety {
  display: flex; gap: 1.15rem; align-items: flex-start;
  background: linear-gradient(180deg, #fff8ef, #fff3e2);
  border: 1px solid #f6c690; border-left: 6px solid var(--accent);
  max-width: 72rem;
  margin: clamp(1.25rem, 3vw, 2rem) auto;
  width: calc(100% - 2 * clamp(1rem, 5vw, 4rem));
  padding: 1.35rem 1.6rem; border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
}
.safety svg { width: 36px; height: 36px; flex: none; color: var(--accent-ink); margin-top: 0.15rem; }
.safety h2 { font-size: 1.12rem; }
.safety p { margin: 0; color: #7c4a1e; font-size: 0.94rem; }

/* ─── Sections ───────────────────────────────────────── */
.section { padding: clamp(3rem, 7vw, 5.5rem) clamp(1rem, 5vw, 4rem); }
.section > * { max-width: 72rem; margin-left: auto; margin-right: auto; }
.section-alt {
  background:
    radial-gradient(40rem 20rem at 100% 0%, rgba(47, 111, 237, 0.06), transparent 60%),
    #edf1f9;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.section-head { max-width: 62ch; margin-bottom: 2.25rem; margin-left: auto; margin-right: auto; }
.section > .section-head { margin-left: auto; margin-right: auto; max-width: 72rem; }
.section-head > * { max-width: 62ch; }
.section-kicker {
  text-transform: uppercase; letter-spacing: 0.18em; font-size: 0.72rem;
  font-weight: 800; color: var(--accent-ink); margin-bottom: 0.5rem;
}
.section-head h2 { font-size: clamp(1.7rem, 3.6vw, 2.4rem); font-weight: 800; }
.section-head p { color: var(--ink-soft); }

/* ─── Filters ────────────────────────────────────────── */
.filters { display: flex; flex-wrap: wrap; gap: 0.55rem; margin-bottom: 1.4rem; }
.filter {
  border: 1.5px solid var(--line); background: var(--card); color: var(--ink-soft);
  padding: 0.52rem 1.15rem; border-radius: 999px;
  font-family: var(--font-body); font-weight: 600; font-size: 0.9rem; cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: border-color 0.15s ease, color 0.15s ease, background 0.15s ease, transform 0.15s ease, box-shadow 0.15s ease;
}
.filter:hover { border-color: var(--sky-3); color: var(--sky-2); transform: translateY(-1px); }
.filter.is-active {
  background: linear-gradient(120deg, var(--sky-1), var(--sky-3));
  border-color: var(--sky-2); color: #fff;
  box-shadow: 0 6px 16px rgba(8, 28, 56, 0.28);
}

/* ─── Progress ───────────────────────────────────────── */
.progress-wrap {
  display: flex; align-items: center; gap: 1rem; flex-wrap: wrap;
  margin-bottom: 2rem;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 0.7rem 1.25rem;
  box-shadow: var(--shadow-sm);
}
.progress-bar {
  flex: 1 1 220px; height: 11px; background: #e6ebf5;
  border-radius: 999px; overflow: hidden;
  box-shadow: inset 0 1px 2px rgba(15, 23, 38, 0.08);
}
.progress-fill {
  height: 100%; width: 0%;
  background: linear-gradient(90deg, var(--accent), var(--accent-soft));
  border-radius: 999px;
  transition: width 0.45s cubic-bezier(0.22, 1, 0.36, 1);
}
#progressLabel {
  margin: 0; font-size: 0.88rem; font-weight: 600; color: var(--ink-soft);
  font-variant-numeric: tabular-nums;
}
.link-btn {
  background: none; border: none; font: inherit; font-size: 0.85rem; font-weight: 600;
  color: var(--sky-3); text-decoration: underline; text-underline-offset: 3px;
  cursor: pointer; padding: 0;
}
.link-btn:hover { color: var(--accent-ink); }

/* ─── Tutorial cards ─────────────────────────────────── */
.tutorial-grid {
  list-style: none; margin: 0; padding: 0;
  display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 1.35rem;
}
.card {
  position: relative;
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 1.45rem 1.45rem 1.25rem; display: flex; flex-direction: column; gap: 0.55rem;
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease;
}
.card::before {
  content: "";
  position: absolute; top: 0; left: 0; right: 0; height: 4px;
  background: var(--line);
  transition: background 0.18s ease;
}
.card[data-track="upper"]::before { background: linear-gradient(90deg, var(--upper), #6f9bff); }
.card[data-track="lower"]::before { background: linear-gradient(90deg, var(--lower), #3fd39b); }
.card[data-track="prosthetic"]::before { background: linear-gradient(90deg, var(--prosthetic), #b673f0); }
.card[data-track="foundation"]::before { background: linear-gradient(90deg, var(--foundation), #e08a2e); }
.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: #cdd8ea;
}
.card.is-done { border-color: #9adbbc; background: linear-gradient(180deg, #f2fbf7, #eafaf2); }
.card.is-done::before { background: linear-gradient(90deg, var(--done), #3fd39b); }
.card h3 { font-size: 1.08rem; font-weight: 700; }
.card p { color: var(--ink-soft); font-size: 0.92rem; flex: 1; }
.card-top { display: flex; justify-content: space-between; align-items: center; gap: 0.5rem; }
.meta { font-size: 0.76rem; color: var(--ink-faint); font-weight: 600; white-space: nowrap; font-variant-numeric: tabular-nums; }
.tag {
  font-size: 0.7rem; font-weight: 800; text-transform: uppercase; letter-spacing: 0.09em;
  padding: 0.3rem 0.75rem; border-radius: 999px; color: #fff;
}
.tag-upper { background: var(--upper); box-shadow: 0 3px 10px rgba(47, 111, 237, 0.32); }
.tag-lower { background: var(--lower); box-shadow: 0 3px 10px rgba(14, 159, 110, 0.32); }
.tag-prosthetic { background: var(--prosthetic); box-shadow: 0 3px 10px rgba(139, 48, 224, 0.32); }
.tag-foundation { background: var(--foundation); box-shadow: 0 3px 10px rgba(180, 83, 9, 0.32); }
.card-foot { display: flex; justify-content: space-between; align-items: center; gap: 0.75rem; margin-top: 0.45rem; }
.level {
  font-size: 0.76rem; font-weight: 700; padding: 0.28rem 0.7rem; border-radius: 8px;
  background: #eef2f9; color: var(--ink-soft); border: 1px solid var(--line);
}
.level-4 { background: #fdeade; color: var(--accent-ink); border-color: #f6c690; }
.btn-complete {
  font-family: var(--font-body); font-size: 0.84rem; font-weight: 700; cursor: pointer;
  border: 1.5px solid var(--sky-3); color: var(--sky-2); background: transparent;
  padding: 0.48rem 1.05rem; border-radius: 999px;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease, box-shadow 0.15s ease;
}
.btn-complete:hover { background: var(--sky-2); color: #fff; }
.btn-complete[aria-pressed="true"] {
  background: var(--done); border-color: var(--done); color: #fff;
  box-shadow: 0 4px 12px rgba(14, 159, 110, 0.32);
}
.empty-note { color: var(--ink-soft); font-style: italic; padding: 2rem 0; text-align: center; }

/* ─── Roadmap ────────────────────────────────────────── */
.roadmap {
  list-style: none; margin: 0 auto; padding: 0;
  display: grid; gap: 0; max-width: 48rem;
  position: relative;
}
.roadmap li {
  position: relative;
  display: flex; gap: 1.2rem; align-items: flex-start;
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 1.3rem 1.5rem;
  box-shadow: var(--shadow-sm);
  transition: transform 0.18s ease, box-shadow 0.18s ease;
}
.roadmap li + li { margin-top: 1.9rem; }
.roadmap li + li::before {
  content: "";
  position: absolute; left: 2.65rem; top: -1.95rem;
  width: 2px; height: 1.95rem;
  background: linear-gradient(180deg, var(--line), var(--sky-3));
}
.roadmap li:hover { transform: translateX(4px); box-shadow: var(--shadow-lg); }
.step-num {
  flex: none; width: 2.5rem; height: 2.5rem; border-radius: 50%;
  background: linear-gradient(140deg, var(--sky-1), var(--sky-3)); color: #fff;
  display: grid; place-items: center;
  font-family: var(--font-display); font-weight: 800; font-size: 1.02rem;
  box-shadow: 0 4px 12px rgba(8, 28, 56, 0.3);
}
.roadmap li:last-child .step-num {
  background: linear-gradient(140deg, var(--accent), var(--accent-soft));
  box-shadow: 0 4px 12px rgba(255, 107, 53, 0.4);
}
.roadmap h3 { font-size: 1.05rem; font-weight: 700; }
.roadmap p { margin: 0; color: var(--ink-soft); font-size: 0.92rem; }

/* ─── Gear ───────────────────────────────────────────── */
.gear-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 1.2rem; }
.gear-card {
  position: relative;
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 1.35rem 1.45rem;
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  transition: transform 0.18s ease, box-shadow 0.18s ease;
}
.gear-card::before {
  content: "";
  position: absolute; top: 0; left: 0; right: 0; height: 4px;
  background: linear-gradient(90deg, var(--accent), var(--accent-soft));
}
.gear-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.gear-card h3 { font-size: 1rem; font-weight: 700; }
.gear-card p { margin: 0; color: var(--ink-soft); font-size: 0.9rem; }

/* ─── FAQ ────────────────────────────────────────────── */
.faq-list { max-width: 48rem; margin: 0 auto; display: grid; gap: 0.8rem; }
.faq-list details {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 0 1.4rem;
  box-shadow: var(--shadow-sm);
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
.faq-list details[open] { border-color: #f6c690; box-shadow: var(--shadow-lg); }
.faq-list summary {
  cursor: pointer; font-family: var(--font-display); font-weight: 600; font-size: 0.99rem;
  padding: 1.05rem 2.2rem 1.05rem 0; list-style: none; position: relative;
}
.faq-list summary::-webkit-details-marker { display: none; }
.faq-list summary::after {
  content: ""; position: absolute; right: 0.15rem; top: 50%;
  width: 0.6rem; height: 0.6rem;
  border-right: 2.5px solid var(--accent-ink); border-bottom: 2.5px solid var(--accent-ink);
  transform: translateY(-70%) rotate(45deg);
  transition: transform 0.2s ease;
}
.faq-list details[open] summary::after { transform: translateY(-30%) rotate(225deg); }
.faq-list details p { color: var(--ink-soft); padding-bottom: 1.2rem; margin: 0; font-size: 0.95rem; }

/* ─── Footer ─────────────────────────────────────────── */
.site-footer {
  background:
    radial-gradient(36rem 16rem at 50% 130%, rgba(60, 118, 200, 0.28), transparent 65%),
    var(--sky-1);
  color: #c6d5ee;
  padding: 2.5rem clamp(1rem, 5vw, 4rem);
  text-align: center;
  border-top: 3px solid var(--accent);
}
.site-footer strong { color: #fff; font-family: var(--font-display); }
.footnote { font-size: 0.82rem; color: #8fa7cc; margin: 0.5rem 0 0; }

/* ─── Entrance animation ─────────────────────────────── */
@media (prefers-reduced-motion: no-preference) {
  .hero-inner > *, .card, .gear-card, .roadmap li {
    animation: rise-in 0.6s cubic-bezier(0.22, 1, 0.36, 1) backwards;
  }
  .hero-inner > *:nth-child(2) { animation-delay: 0.07s; }
  .hero-inner > *:nth-child(3) { animation-delay: 0.14s; }
  .hero-inner > *:nth-child(4) { animation-delay: 0.21s; }
  .hero-inner > *:nth-child(5) { animation-delay: 0.28s; }
  .card:nth-child(3n + 2) { animation-delay: 0.06s; }
  .card:nth-child(3n) { animation-delay: 0.12s; }
  @keyframes rise-in {
    from { opacity: 0; transform: translateY(14px); }
    to { opacity: 1; transform: translateY(0); }
  }
}

/* ─── Responsive ─────────────────────────────────────── */
@media (max-width: 720px) {
  .site-header { flex-direction: column; gap: 0.4rem; padding-bottom: 0.6rem; }
  .hero-stats { gap: 0.8rem; }
  .hero-stats > div { flex: 1 1 8rem; min-width: 0; padding: 0.75rem 1rem; }
  .safety { flex-direction: column; }
  .card-foot { flex-wrap: wrap; }
  .progress-wrap { border-radius: var(--radius); }
  .roadmap li + li::before { left: 2.55rem; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition: none !important; animation: none !important; }
}