:root {
  --bg: #f5f6f8;
  --card-bg: #ffffff;
  --text: #1c1e21;
  --muted: #6b7280;
  --accent: #2563eb;
  --accent-active: #1d4ed8;
  --error: #dc2626;
  --border: #e5e7eb;
  color-scheme: light;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Microsoft YaHei", sans-serif;
  -webkit-tap-highlight-color: transparent;
}

.app {
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  max-width: 480px;
  margin: 0 auto;
}

.progress-bar {
  padding: 12px 16px 8px;
}

.progress-track {
  height: 6px;
  border-radius: 3px;
  background: var(--border);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--accent);
  width: 0%;
  transition: width 0.25s ease;
}

.progress-label {
  margin-top: 6px;
  font-size: 13px;
  color: var(--muted);
  text-align: right;
}

main#view {
  flex: 1;
  display: flex;
  flex-direction: column;
  padding: 16px;
  gap: 16px;
}

.loading {
  margin: auto;
  color: var(--muted);
  font-size: 15px;
}

.image-card {
  background: var(--card-bg);
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 1px 3px rgba(0,0,0,0.08);
  position: relative;
}

.image-card img {
  display: block;
  width: 100%;
  aspect-ratio: 4 / 3;
  object-fit: cover;
  cursor: pointer;
  background: #d1d5db;
}

.image-hint-badge {
  position: absolute;
  bottom: 10px;
  right: 10px;
  background: rgba(0,0,0,0.55);
  color: #fff;
  font-size: 12px;
  padding: 4px 10px;
  border-radius: 999px;
  pointer-events: none;
}

.answer-panel {
  background: var(--card-bg);
  border-radius: 16px;
  padding: 16px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.08);
  display: flex;
  flex-direction: column;
  gap: 10px;
  animation: rise 0.2s ease;
}

@keyframes rise {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

.answer-panel label {
  font-size: 14px;
  color: var(--muted);
}

.answer-panel input[type="number"] {
  font-size: 22px;
  padding: 12px 14px;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  width: 100%;
  outline: none;
  -moz-appearance: textfield;
}

.answer-panel input[type="number"]:focus {
  border-color: var(--accent);
}

.answer-panel .error-text {
  color: var(--error);
  font-size: 13px;
  min-height: 18px;
}

.actions {
  margin-top: auto;
  display: flex;
  gap: 10px;
  padding-top: 8px;
}

button.primary {
  flex: 1;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 12px;
  font-size: 16px;
  font-weight: 600;
  padding: 14px;
  cursor: pointer;
}

button.primary:active {
  background: var(--accent-active);
}

button.primary:disabled {
  background: #a7b6d6;
  cursor: not-allowed;
}

.thank-you {
  margin: auto;
  text-align: center;
  padding: 32px 16px;
}

.thank-you h1 {
  font-size: 22px;
  margin-bottom: 8px;
}

.thank-you p {
  color: var(--muted);
  font-size: 15px;
}

.error-screen {
  margin: auto;
  text-align: center;
  color: var(--error);
  padding: 16px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #17181a;
    --card-bg: #232426;
    --text: #f0f1f3;
    --muted: #9aa0a8;
    --border: #34363a;
    color-scheme: dark;
  }
  .image-card img { background: #3a3c40; }
}