:root {
  --bg: color-mix(in oklab, Canvas 92%, black);
  --panel: color-mix(in oklab, Canvas 92%, white);
  --text: CanvasText;
  --muted: color-mix(in oklab, CanvasText 55%, Canvas 45%);
  --muted2: color-mix(in oklab, CanvasText 18%, Canvas 82%);
  --primary: color-mix(in oklab, Highlight 75%, #6d28d9 25%);
  --ring: color-mix(in oklab, Highlight 40%, Canvas 60%);

  --radius: 18px;
  --shadow: 0 12px 40px color-mix(in oklab, black 20%, transparent);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: color-mix(in oklab, #0b0f17 90%, black);
    --panel: color-mix(in oklab, #0f1623 92%, black);
    --shadow: 0 14px 55px color-mix(in oklab, black 45%, transparent);
  }
}

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

html,
body {
  height: 100%;
}

body {
  margin: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica,
    Arial, "Apple Color Emoji", "Segoe UI Emoji";
  color: var(--text);
  background: radial-gradient(
      1200px 800px at 50% 50%,
      color-mix(in oklab, var(--primary) 18%, transparent),
      transparent 60%
    ),
    var(--bg);
}

.wrap {
  min-height: 100%;
  display: grid;
  place-items: center;
  padding: clamp(16px, 3vw, 40px);
}

.card {
  width: min(720px, 100%);
  background: var(--panel);
  border: 1px solid color-mix(in oklab, var(--text) 10%, transparent);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: clamp(20px, 4vw, 40px);
  display: grid;
  gap: 28px;
  text-align: center;
}

.header {
  display: grid;
  gap: 8px;
}

h1 {
  margin: 0;
  font-weight: 800;
  letter-spacing: -0.02em;
  font-size: clamp(2.25rem, 4.5vw, 3.25rem);
}

.subtitle {
  margin: 0;
  color: var(--muted);
  font-size: clamp(1rem, 2vw, 1.125rem);
}

.display {
  min-height: 8rem;
  display: grid;
  place-items: center;
}

.number {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas,
    "Liberation Mono", "Courier New", monospace;
  font-weight: 800;
  font-size: clamp(3.25rem, 9vw, 5.25rem);
  color: var(--primary);
  transform: translateZ(0);
  will-change: transform, opacity;
  transition: transform 150ms ease, opacity 150ms ease;
}

.number--placeholder {
  color: color-mix(in oklab, var(--muted2) 65%, transparent);
  font-weight: 600;
}

.is-animating .number {
  transform: scale(0.95);
  opacity: 0.5;
}

.btn {
  margin-inline: auto;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;

  font-size: 1.125rem;
  font-weight: 700;

  padding: 14px 22px;
  border-radius: 14px;
  border: 1px solid color-mix(in oklab, var(--text) 12%, transparent);
  background: color-mix(in oklab, var(--primary) 16%, var(--panel));
  color: var(--text);
  cursor: pointer;
  user-select: none;
  -webkit-tap-highlight-color: transparent;

  transition: transform 120ms ease, background 120ms ease, border-color 120ms ease;
}

.btn:hover {
  background: color-mix(in oklab, var(--primary) 22%, var(--panel));
  border-color: color-mix(in oklab, var(--text) 18%, transparent);
}

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

.btn:focus-visible {
  outline: 3px solid var(--ring);
  outline-offset: 3px;
}

.btn[disabled] {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
}

.icon {
  flex: 0 0 auto;
}

.explanation {
  margin: 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.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;
}

@media (prefers-reduced-motion: reduce) {
  .number,
  .btn {
    transition: none;
  }
}