/* Axiom design tokens and shared components. Light theme only, by design. */

:root {
  color-scheme: light;

  --ink: #1d1d1f;
  --ink-2: #6e6e73;
  --ink-3: #86868b;
  --surface: #ffffff;
  --surface-2: #f5f5f7;
  --surface-3: #e8e8ed;
  --line: rgba(0, 0, 0, 0.08);
  --accent: #2563eb;
  --accent-ink: #ffffff;
  --accent-soft: rgba(37, 99, 235, 0.1);
  --ok: #1a7f37;
  --ok-soft: rgba(26, 127, 55, 0.12);
  --bad: #c62828;
  --bad-soft: rgba(198, 40, 40, 0.1);
  --warn: #b45309;

  --font: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", Inter,
    "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;

  --radius-s: 10px;
  --radius-m: 18px;
  --radius-l: 28px;

  --shadow-s: 0 1px 2px rgba(0, 0, 0, 0.04), 0 4px 12px rgba(0, 0, 0, 0.05);
  --shadow-m: 0 2px 4px rgba(0, 0, 0, 0.04), 0 16px 48px rgba(0, 0, 0, 0.08);
  --shadow-l: 0 8px 16px rgba(0, 0, 0, 0.05), 0 40px 100px rgba(0, 0, 0, 0.12);

  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
  --ease-in-out: cubic-bezier(0.65, 0, 0.35, 1);
  --dur-1: 220ms;
  --dur-2: 480ms;
  --dur-3: 900ms;

  --nav-h: 52px;
  --container: 1120px;
  --gutter: 24px;
}

@media (prefers-reduced-motion: reduce) {
  :root {
    --dur-1: 1ms;
    --dur-2: 1ms;
    --dur-3: 1ms;
  }
}

@media (max-width: 640px) {
  :root {
    --gutter: 16px;
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  /* clip, not hidden: it stops 3D overhang from causing a horizontal scrollbar
     without turning the root into a scroll container, so position: sticky keeps working */
  overflow-x: hidden; /* for engines without clip */
  overflow-x: clip;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}

body {
  margin: 0;
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.5;
  color: var(--ink);
  background: var(--surface);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img,
svg,
video {
  display: block;
  max-width: 100%;
}

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

button,
input,
select {
  font: inherit;
  color: inherit;
}

button {
  cursor: pointer;
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.container {
  width: min(100% - 2 * var(--gutter), var(--container));
  margin-inline: auto;
}

/* Type */

.eyebrow {
  margin: 0 0 12px;
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  color: var(--accent);
}

.display {
  margin: 0;
  font-size: clamp(40px, 7vw, 80px);
  line-height: 1.02;
  letter-spacing: -0.03em;
  font-weight: 700;
}

.title {
  margin: 0;
  font-size: clamp(30px, 4.6vw, 52px);
  line-height: 1.06;
  letter-spacing: -0.025em;
  font-weight: 700;
}

.subtitle {
  margin: 0;
  font-size: clamp(22px, 2.6vw, 28px);
  line-height: 1.2;
  letter-spacing: -0.015em;
  font-weight: 600;
}

.lead {
  margin: 0;
  font-size: clamp(19px, 2vw, 23px);
  line-height: 1.4;
  letter-spacing: -0.01em;
  color: var(--ink-2);
}

.muted {
  color: var(--ink-2);
}

.small {
  font-size: 14px;
}

/* Buttons */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 0 22px;
  border-radius: 999px;
  border: 1px solid transparent;
  font-weight: 600;
  font-size: 17px;
  line-height: 1;
  transition:
    transform var(--dur-1) var(--ease-out),
    background-color var(--dur-1),
    color var(--dur-1),
    border-color var(--dur-1),
    box-shadow var(--dur-1);
}

.btn:hover {
  transform: translateY(-1px);
}

.btn:active {
  transform: translateY(0) scale(0.98);
}

.btn-primary {
  background: var(--ink);
  color: #fff;
}

.btn-primary:hover {
  background: #000;
}

.btn-secondary {
  background: var(--surface);
  color: var(--ink);
  border-color: var(--line);
  box-shadow: var(--shadow-s);
}

.btn-secondary:hover {
  border-color: rgba(0, 0, 0, 0.16);
}

.btn-small {
  min-height: 36px;
  padding: 0 16px;
  font-size: 15px;
}

/* Nav */

.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  height: var(--nav-h);
  background: rgba(255, 255, 255, 0.72);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--line);
}

.nav-inner {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.wordmark {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  min-height: 44px;
  font-weight: 700;
  font-size: 19px;
  letter-spacing: -0.02em;
}

.wordmark-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 4px var(--accent-soft);
}

.nav-links {
  display: flex;
  gap: 28px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: 14px;
  font-weight: 500;
  color: var(--ink-2);
}

.nav-links a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding-inline: 6px;
  margin-inline: -6px;
  transition: color var(--dur-1);
}

.nav-links a:hover,
.nav-links a[aria-current="page"] {
  color: var(--ink);
}

/* Cards and chips */

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-m);
  box-shadow: var(--shadow-s);
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 600;
  background: var(--surface-2);
  color: var(--ink-2);
  white-space: nowrap;
}

.chip-accent {
  background: var(--accent-soft);
  color: var(--accent);
}

.chip-ok {
  background: var(--ok-soft);
  color: var(--ok);
}

/* Question card: the same component shows a question in the hero and in the bank */

.q-card {
  display: grid;
  gap: 20px;
  padding: clamp(20px, 3vw, 36px);
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-l);
  box-shadow: var(--shadow-l);
}

.q-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--ink-3);
}

.q-stem {
  margin: 0;
  font-size: clamp(18px, 1.8vw, 22px);
  line-height: 1.45;
  letter-spacing: -0.01em;
}

.q-table {
  border-collapse: collapse;
  font-size: 15px;
}

.q-table caption {
  padding-bottom: 8px;
  font-size: 14px;
  color: var(--ink-2);
  text-align: left;
}

.q-table th,
.q-table td {
  padding: 8px 14px;
  border: 1px solid var(--line);
  text-align: center;
}

.q-table th {
  background: var(--surface-2);
  font-weight: 600;
}

.q-table th[scope="row"] {
  text-align: left;
}

.choices {
  display: grid;
  gap: 10px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.choice {
  display: flex;
  align-items: center;
  gap: 14px;
  width: 100%;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--surface);
  font-size: 17px;
  text-align: left;
  transition:
    border-color var(--dur-1),
    background-color var(--dur-1),
    opacity var(--dur-1);
}

.choice:hover {
  border-color: rgba(0, 0, 0, 0.2);
}

.choice-key {
  flex: none;
  display: grid;
  place-items: center;
  width: 30px;
  height: 30px;
  border: 1.5px solid var(--ink-3);
  border-radius: 50%;
  font-size: 14px;
  font-weight: 600;
  color: var(--ink-2);
}

.choice.is-selected {
  border-color: var(--ink);
}

.choice.is-selected .choice-key {
  background: var(--ink);
  border-color: var(--ink);
  color: #fff;
}

.choice.is-correct {
  border-color: var(--ok);
  background: var(--ok-soft);
}

.choice.is-correct .choice-key {
  background: var(--ok);
  border-color: var(--ok);
  color: #fff;
}

.choice.is-incorrect {
  border-color: var(--bad);
  background: var(--bad-soft);
}

.choice.is-incorrect .choice-key {
  background: var(--bad);
  border-color: var(--bad);
  color: #fff;
}

.choice.is-eliminated {
  border-style: dashed;
  color: var(--ink-2);
}

.choice.is-eliminated .choice-key {
  border-color: var(--ink-2);
  color: var(--ink-2);
}

.choice.is-eliminated .choice-text {
  text-decoration: line-through;
}

.explanation {
  margin: 0;
  padding: 4px 0 4px 16px;
  border-left: 3px solid var(--accent);
  font-size: 16px;
  line-height: 1.55;
  color: var(--ink-2);
}

/* Footer */

.footer {
  padding: 40px 0;
  border-top: 1px solid var(--line);
  font-size: 14px;
  color: var(--ink-2);
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.footer a:hover {
  color: var(--ink);
}

.footer-copy {
  margin: 0;
}

.footer-links {
  display: flex;
  align-items: center;
  gap: 10px;
}

.footer-links a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding-inline: 6px;
  margin-inline: -6px;
}

@media (max-width: 640px) {
  .nav-github {
    display: none;
  }
}