:root {
  --bg: #f5f7fb;
  --panel: #fff;
  --ink: #182033;
  --muted: #667085;
  --line: #e5e9f2;
  --accent: #3563ff;
  --accent-dark: #244bd4;
  --mint: #008000;
  --mint-dark: #005c00;
  --warning: #f59e0b;
  --coral: #ff6b5f;
  --shadow: 0 24px 70px rgba(23, 32, 51, 0.12);
  /* Blue-to-green fade length. Runs entirely in CSS, over the first seconds
     of tracking while the balls are already moving. */
  --ball-fade: 3000ms;
}

* {
  box-sizing: border-box;
}

/* Beats the display values set on .timer-card / .track-time-group, which would
   otherwise override the browser's default [hidden] rule. */
[hidden] {
  display: none !important;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont,
    "Segoe UI", sans-serif;
  background:
    radial-gradient(circle at top left, rgba(53, 99, 255, 0.12), transparent 34rem),
    linear-gradient(145deg, #f8fbff 0%, var(--bg) 48%, #eef4f1 100%);
}

button {
  font: inherit;
}

button,
a {
  -webkit-tap-highlight-color: transparent;
}

/* Header */
.site-header {
  width: min(1180px, calc(100% - 32px));
  margin: 0 auto;
  padding-top: 16px;
}

.home-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.9);
  box-shadow: 0 10px 24px rgba(23, 32, 51, 0.08);
  color: var(--ink);
  font-size: 0.88rem;
  font-weight: 800;
  text-decoration: none;
  transition: transform 160ms ease, box-shadow 160ms ease;
}

.home-link:hover {
  transform: translateY(-2px);
  box-shadow: 0 14px 30px rgba(23, 32, 51, 0.12);
}

/* Layout */
.app-shell {
  width: min(1180px, calc(100% - 32px));
  min-height: calc(100vh - 62px);
  margin: 0 auto;
  padding: 16px 0 32px;
  animation: riseIn 420ms ease both;
}

.hero {
  width: min(720px, 100%);
  margin: 0 auto;
  padding: clamp(18px, 4vw, 32px) 0 clamp(20px, 4vw, 30px);
  text-align: center;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 5.4vw, 3.4rem);
  font-weight: 900;
  line-height: 1.05;
}

.subtitle {
  width: min(520px, 100%);
  margin: 16px auto 0;
  color: var(--muted);
  font-size: clamp(1rem, 2vw, 1.15rem);
  font-weight: 600;
  line-height: 1.55;
}

.game-area {
  width: min(560px, 100%);
  margin: 0 auto;
}

/* Settings */
.settings-panel {
  display: grid;
  grid-template-columns: 1.25fr 1fr 1fr;
  gap: 10px;
  margin-bottom: 14px;
}

.choice-group {
  min-width: 0;
  margin: 0;
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.92);
  box-shadow: 0 12px 34px rgba(23, 32, 51, 0.07);
}

.choice-group legend {
  padding: 0 6px;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.choice-options {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 6px;
}

.choice-options.four {
  grid-template-columns: repeat(4, 1fr);
}

.setting-button {
  min-width: 0;
  height: 36px;
  padding: 0 6px;
  border: 1px solid #dfe6f0;
  border-radius: 8px;
  color: var(--ink);
  background: #f1f5fb;
  font-size: 0.85rem;
  font-weight: 800;
  cursor: pointer;
  transition: transform 180ms ease, background 180ms ease, color 180ms ease,
    border-color 180ms ease;
}

.setting-button:hover:not(:disabled) {
  transform: translateY(-2px);
}

.setting-button.active {
  color: #fff;
  border-color: var(--accent);
  background: var(--accent);
}

.setting-button:disabled {
  opacity: 0.5;
  cursor: default;
}

/* Status row */
.status-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 12px;
}

.status-badge {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 12px 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  box-shadow: 0 12px 34px rgba(23, 32, 51, 0.08);
  color: var(--muted);
  font-size: 0.86rem;
  font-weight: 700;
}

.status-badge b {
  color: var(--ink);
}

.status-badge span {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: #b4bdcd;
  box-shadow: 0 0 0 4px rgba(180, 189, 205, 0.18);
}

.status-badge.tracking span {
  background: var(--accent);
  box-shadow: 0 0 0 4px rgba(53, 99, 255, 0.16);
  animation: pulse 1s infinite;
}

.status-badge.choose span {
  background: var(--warning);
  box-shadow: 0 0 0 4px rgba(245, 158, 11, 0.18);
}

/* Sits in the status row before a round, then swaps out for the timer card. */
.track-time-group {
  /* Matches .timer-card's footprint so the row doesn't resize on swap. */
  min-width: 214px;
  flex: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 7px 7px 7px 14px;
}

.group-label {
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.track-time-group .choice-options {
  min-width: 150px;
}

.timer-card {
  min-width: 214px;
  flex: none;
  padding: 13px 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 12px 34px rgba(23, 32, 51, 0.08);
}

.timer-card span {
  color: var(--muted);
  font-size: 0.86rem;
  font-weight: 700;
}

.timer-card strong {
  font-size: 1.1rem;
  font-variant-numeric: tabular-nums;
}

/* Arena */
.arena {
  position: relative;
  width: min(100%, max(280px, calc(100dvh - 430px)));
  margin-inline: auto;
  aspect-ratio: 1 / 1;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.92);
  box-shadow: var(--shadow);
  isolation: isolate;
}

.grid {
  position: absolute;
  inset: 0;
  z-index: -1;
  opacity: 0.5;
  background-image: linear-gradient(var(--line) 1px, transparent 1px),
    linear-gradient(90deg, var(--line) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: radial-gradient(circle, #000, transparent 85%);
}

/* The ball is green underneath, with the blue gradient stacked on top as a
   pseudo-element. Swapping colour crossfades that layer's opacity, because a
   transition between two gradient *images* is discrete in every engine — the
   browser flips them at the halfway point instead of blending. */
.ball {
  position: absolute;
  width: clamp(38px, 9.5%, 52px);
  aspect-ratio: 1;
  padding: 0;
  border: 0;
  border-radius: 50%;
  background: radial-gradient(circle at 34% 28%, #4cc44c 0 11%, var(--mint) 38%, var(--mint-dark) 100%);
  box-shadow: 0 8px 18px rgba(0, 128, 0, 0.22),
    inset -3px -5px 8px rgba(0, 64, 0, 0.18),
    inset 3px 3px 7px rgba(255, 255, 255, 0.28);
  transform: translate3d(0, 0, 0);
  transition: box-shadow 200ms ease, filter 200ms ease;
}

.ball::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 50%;
  opacity: 0;
  pointer-events: none;
  background: radial-gradient(circle at 34% 28%, #86a8ff 0 11%, var(--accent) 38%, var(--accent-dark) 100%);
  box-shadow: inset -3px -5px 8px rgba(16, 45, 145, 0.18),
    inset 3px 3px 7px rgba(255, 255, 255, 0.3);
  transition: opacity 350ms ease;
}

.ball.target-visible::after {
  opacity: 1;
}

.ball.target-visible {
  box-shadow: 0 8px 18px rgba(53, 99, 255, 0.26),
    inset -3px -5px 8px rgba(16, 45, 145, 0.18),
    inset 3px 3px 7px rgba(255, 255, 255, 0.3);
}

/* Applied only for the blue-to-green change at the start of tracking, so the
   snap back to blue at the result stays quick. */
.ball.slow-fade {
  transition: box-shadow var(--ball-fade) linear, filter 200ms ease;
}

.ball.slow-fade::after {
  transition: opacity var(--ball-fade) linear;
}

.ball.selectable {
  cursor: pointer;
}

/* Hover highlights in place — no scaling or movement. */
.ball.selectable:hover,
.ball.selectable:focus-visible {
  outline: none;
  filter: brightness(1.08);
  box-shadow: 0 0 0 4px rgba(245, 158, 11, 0.28), 0 8px 18px rgba(23, 32, 51, 0.16);
}

.ball.selected,
.ball.selectable.selected:hover {
  filter: brightness(1.05);
  box-shadow: 0 0 0 4px var(--warning), 0 8px 18px rgba(245, 158, 11, 0.3);
}

.ball.correct {
  box-shadow: 0 0 0 4px var(--mint), 0 8px 18px rgba(0, 128, 0, 0.32);
}

.ball.wrong {
  opacity: 0.4;
  box-shadow: 0 0 0 4px var(--coral), 0 8px 18px rgba(255, 107, 95, 0.28);
}

.countdown-number {
  position: absolute;
  inset: 0;
  /* Over the balls, under the result card. */
  z-index: 3;
  display: grid;
  place-items: center;
  pointer-events: none;
  color: var(--accent);
  font-size: clamp(5rem, 16vw, 9rem);
  font-weight: 800;
  line-height: 1;
}

.countdown-number.pop {
  animation: countPulse 0.9s ease both;
}

.result-card {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  z-index: 4;
  width: min(84%, 330px);
  padding: 26px;
  text-align: center;
  border: 1px solid rgba(255, 255, 255, 0.6);
  border-radius: 8px;
  /* Half-transparent, and no backdrop blur, so the highlighted ball behind the
     card stays readable. */
  background: rgba(255, 255, 255, 0.5);
  box-shadow: var(--shadow);
}

.result-icon {
  width: 52px;
  height: 52px;
  margin: 0 auto 12px;
  display: grid;
  place-items: center;
  color: #fff;
  background: var(--mint);
  border-radius: 50%;
  font-size: 1.5rem;
  font-weight: 800;
}

.result-card h2 {
  margin: 0 0 6px;
  font-size: clamp(1.4rem, 4vw, 1.75rem);
  font-weight: 900;
  line-height: 1.1;
}

.result-card p {
  margin: 0;
  color: var(--muted);
  font-size: 0.92rem;
  font-weight: 600;
  line-height: 1.5;
}

/* Actions */
.primary-button {
  width: 100%;
  min-height: 52px;
  margin-top: 16px;
  padding: 0 28px;
  border: 0;
  border-radius: 8px;
  color: #fff;
  font-weight: 800;
  background: var(--accent);
  box-shadow: 0 18px 34px rgba(53, 99, 255, 0.24);
  cursor: pointer;
  transition: transform 180ms ease, background 180ms ease;
}

.primary-button:hover:not(:disabled) {
  transform: translateY(-2px);
  background: var(--accent-dark);
}

.primary-button:disabled {
  opacity: 0.55;
  cursor: default;
}

.tip {
  margin: 14px 0 0;
  color: var(--muted);
  font-size: 0.86rem;
  font-weight: 600;
  text-align: center;
}

@keyframes pulse {
  50% {
    transform: scale(1.35);
  }
}

/* Peaks translucent, not solid — it sits over the balls and must not hide
   the one that is fading. */
@keyframes countPulse {
  0% {
    opacity: 0;
    transform: scale(0.72);
  }

  35% {
    opacity: 0.5;
    transform: scale(1.06);
  }

  100% {
    opacity: 0;
    transform: scale(1.2);
  }
}

@keyframes riseIn {
  from {
    opacity: 0;
    transform: translateY(12px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 640px) {
  .site-header,
  .app-shell {
    width: min(100% - 24px, 1180px);
  }

  .settings-panel {
    grid-template-columns: 1fr;
    gap: 8px;
  }

  .status-row {
    flex-direction: column;
    align-items: stretch;
  }

  .timer-card,
  .track-time-group {
    width: 100%;
    min-width: 0;
  }

  .arena {
    width: min(100%, max(260px, calc(100dvh - 470px)));
  }
}

@media (max-height: 820px) {
  .tip {
    display: none;
  }

  .hero {
    padding-top: 10px;
    padding-bottom: 16px;
  }

  h1 {
    font-size: clamp(1.7rem, 4vw, 2.4rem);
  }

  .subtitle {
    margin-top: 10px;
    font-size: 0.98rem;
  }

  .arena {
    width: min(100%, max(250px, calc(100dvh - 390px)));
  }
}

@media (prefers-reduced-motion: reduce) {
  .app-shell,
  .primary-button,
  .ball,
  .setting-button,
  .home-link {
    animation: none;
    transition: none;
  }

  .status-badge.tracking span {
    animation: none;
  }
}