:root {
  color-scheme: dark;

  /* Palette (HSL so it's easy to tweak) */
  --bg: hsl(0 0% 10%); /* #1a1a1a */
  --surface: hsl(0 0% 16%); /* #292929 */
  --surface-2: hsl(210 20% 10%); /* darker overlay */
  --text: hsl(0 0% 98%);
  --muted: hsl(0 0% 60%);
  --muted-2: hsl(0 0% 40%);

  --blue: hsl(217 91% 60%); /* #3b82f6 */
  --green: hsl(142 72% 45%); /* #22c55e */
  --amber: hsl(38 92% 50%); /* #f59e0b */
  --red: hsl(0 84% 60%); /* #ef4444 */

  /* Layout scale */
  --container-min: 320px;
  --container-max: 1400px;
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;

  /* Shape & borders */
  --radius: 12px;
  --border-w: 2px;
  --border: var(--border-w) solid hsl(0 0% 22%);

  /* Typography */
  --font:
    system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, Noto Sans, Helvetica, Arial, 'Apple Color Emoji',
    'Segoe UI Emoji';
  --fs-label: 0.9rem;
  --fs-metric: clamp(2rem, 4vw + 1rem, 3.25rem);

  /* Effects */
  --shadow-1: 0 1px 2px hsl(0 0% 0% / 0.35), 0 8px 24px hsl(0 0% 0% / 0.35);
  --duration-1: 150ms;
  --duration-2: 300ms;
  --duration-3: 600ms;
  --ease-out: cubic-bezier(0.2, 0.8, 0.2, 1);
  --ease-emphasized: cubic-bezier(0.2, 0.7, 0, 1);

  /* Dynamic accent per card/status (overridden by modifiers) */
  --accent: var(--blue);
}

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

html,
body {
  height: 100%;
}

body {
  font-family: var(--font), sans-serif;
  background: var(--bg);
  color: var(--text);
  margin: 0;

  display: grid;
  place-items: center;
}

main {
  padding: var(--space-6);
  min-width: var(--container-min);
  max-width: var(--container-max);
}

/* Header */
.header {
  text-align: center;
  margin-block-end: var(--space-8);
}

.header h1 {
  margin: 0;
  line-height: 1.1;
}

.header p {
  margin: var(--space-2) 0 0;
  color: var(--muted);
}

/* Grid (3/2/1) */
.grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--space-4);
}

@media (max-width: 1024px) {
  .grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 640px) {
  .grid {
    grid-template-columns: 1fr;
  }
}

/* Card */
.card {
  --accent: var(--blue);
  background: var(--surface);
  border: var(--border);
  border-radius: var(--radius);
  padding: var(--space-6);
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  position: relative;
  overflow: clip;
  box-shadow: var(--shadow-1);
  transition:
    border-color var(--duration-1) var(--ease-out),
    transform var(--duration-1) var(--ease-out);
  will-change: transform;
}

.card:hover {
  transform: translateY(-2px);
}

.card h3 {
  margin: 0;
}

.card p {
  margin: var(--space-2) 0 0;
}

.card.static {
  --accent: var(--green);
  border-color: var(--accent);
  background-image: linear-gradient(135deg, var(--surface) 0%, hsl(142 60% 16%) 100%);
}

.card.loading {
  --accent: var(--amber);
  border-color: var(--accent);
}

.card.complete {
  --accent: var(--blue);
  border-color: var(--accent);
  background-image: linear-gradient(135deg, var(--surface) 0%, hsl(217 36% 25%) 100%);
  animation:
    slide-in var(--duration-2) var(--ease-emphasized),
    glow 2s var(--ease-out);
}

/* Loading bar */
.loading-bar {
  position: absolute;
  inset-block-start: 0;
  inset-inline: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--amber), var(--red), var(--amber));
  background-size: 200% 100%;
  animation: loading-bar 1.5s linear infinite;
}

/* Typographic atoms */
.metric {
  font-size: var(--fs-metric);
  font-weight: 800;
  margin-block: var(--space-2);
}

.label {
  color: var(--muted);
  font-size: var(--fs-label);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

/* Status badge */
.status {
  position: absolute;
  inset-block-start: var(--space-4);
  inset-inline-end: var(--space-4);
  padding: 0.3rem 0.7rem;
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 700;
  background: var(--accent);
  color: white;
  box-shadow: 0 0 0 1px hsl(0 0% 0% / 0.15);
}

.status.instant {
  background: var(--green);
}

.status.streaming {
  background: var(--amber);
  animation: pulse 1s ease-in-out infinite;
}

.status.ready {
  background: var(--blue);
}

/* Footer */
.footer {
  text-align: center;
  margin-block-start: var(--space-8);
  color: var(--muted);
  font-size: 0.9rem;
}

.footer strong {
  color: var(--text);
}

.github-link {
  color: var(--muted);
  width: 24px;
  display: inline-flex;
  line-height: 0;
  transition: color var(--duration-1) var(--ease-out);
}

.github-link svg {
  width: 1.25rem;
  height: 1.25rem;
}

.github-link:hover {
  color: var(--text);
}

/* Animations */
@keyframes loading-bar {
  from {
    background-position: 200% 0;
  }
  to {
    background-position: -200% 0;
  }
}

@keyframes slide-in {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes glow {
  0% {
    box-shadow: 0 0 0 hsla(217, 91%, 60%, 0.4);
  }
  40% {
    box-shadow: 0 0 22px hsla(217, 91%, 60%, 0.85);
  }
  100% {
    box-shadow: 0 0 0 hsla(217, 91%, 60%, 0);
  }
}

@keyframes pulse {
  0%,
  100% {
    opacity: 1;
  }
  50% {
    opacity: 0.7;
  }
}

/* Reduced motion: minimize movement without breaking affordances */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}

/* Explain section */
.explain {
  margin-block: var(--space-8);
}

.explain__title {
  margin: 0 0 var(--space-4);
  text-align: center;
  font-size: clamp(1.25rem, 1rem + 1.5vw, 1.75rem);
}

.explain__subtitle {
  margin: 0 0 var(--space-6);
  text-align: center;
  color: var(--muted);
  font-size: 0.95rem;
}

.explain-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--space-4);
}

@media (max-width: 1024px) {
  .explain-grid {
    grid-template-columns: 1fr;
  }
}

.card.explain-card {
  align-items: flex-start;
  text-align: left;
  padding: var(--space-5);
  gap: var(--space-3);
}

.explain-step {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--text);
}

.explain-step .dot {
  width: 0.6rem;
  height: 0.6rem;
  border-radius: 999px;
  background: currentColor;
  box-shadow: 0 0 0 6px hsl(0 0% 100% / 0.05);
}

.explain-card p {
  margin: 0;
  color: var(--muted);
}

.explain-card ul {
  color: var(--muted);
}

.explain-card.instant {
  --accent: var(--green);
  border-color: var(--accent);
}

.explain-card.stream {
  --accent: var(--amber);
  border-color: var(--accent);
}

.explain-card.complete {
  --accent: var(--blue);
  border-color: var(--accent);
}

.explain-result {
  grid-column: 1 / -1;
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: var(--space-4);
  align-items: start;
}

.explain-card.complete {
  animation: none !important;
  background-image: none;
}

.explain-card:hover {
  transform: none !important;
}

@media (max-width: 1024px) {
  .explain-result {
    grid-template-columns: 1fr;
  }
}

.explain-result pre {
  margin: 0;
  padding: var(--space-4);
  background: hsl(0 0% 100% / 0.05);
  border: 1px solid hsl(0 0% 100% / 0.08);
  border-radius: calc(var(--radius) - 2px);
  overflow: auto;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', monospace;
  font-size: 0.85rem;
  line-height: 1.45;
  color: var(--text);
}

.explain-result a {
  color: var(--text);
  text-decoration: underline;
}