/* ── Reset & Variables ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #0f1117;
  --bg-card: #1a1d27;
  --bg-hover: #252836;
  --text: #e4e4e7;
  --text-muted: #9ca3af;
  --accent: #6366f1;
  --accent-hover: #818cf8;
  --success: #22c55e;
  --error: #ef4444;
  --warning: #f59e0b;
  --border: #2d3041;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 4px 24px rgba(0,0,0,0.3);
  --transition: 0.2s ease;
}

[data-theme="light"] {
  --bg: #f8f9fc;
  --bg-card: #ffffff;
  --bg-hover: #f1f3f9;
  --text: #1f2937;
  --text-muted: #6b7280;
  --border: #e5e7eb;
  --shadow: 0 4px 24px rgba(0,0,0,0.08);
}

html { scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
}

a { color: var(--accent); text-decoration: none; }

/* ── Layout ── */
.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ── Header ── */
header {
  padding: 20px 0;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: var(--bg);
  z-index: 100;
  backdrop-filter: blur(12px);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.logo {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--accent);
}
.header-actions {
  display: flex;
  gap: 8px;
}
.header-actions button {
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-size: 0.9rem;
  transition: var(--transition);
}
.header-actions button:hover {
  background: var(--bg-hover);
}

/* ── Hero ── */
.hero {
  text-align: center;
  padding: 48px 0 32px;
}
.hero h1 {
  font-size: 2.2rem;
  font-weight: 800;
  margin-bottom: 12px;
  background: linear-gradient(135deg, var(--accent), #a78bfa, #f472b6);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero p {
  color: var(--text-muted);
  font-size: 1.1rem;
  max-width: 500px;
  margin: 0 auto;
}

/* ── Upload Zone ── */
.upload-zone {
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  padding: 48px 24px;
  text-align: center;
  cursor: pointer;
  transition: var(--transition);
  background: var(--bg-card);
  margin-bottom: 32px;
}
.upload-zone:hover,
.upload-zone.drag-over {
  border-color: var(--accent);
  background: var(--bg-hover);
}
.upload-zone.uploading {
  opacity: 0.6;
  pointer-events: none;
}
.upload-icon {
  font-size: 3rem;
  margin-bottom: 12px;
  display: block;
}
.upload-zone h3 { margin-bottom: 4px; font-size: 1.1rem; }
.upload-zone p { color: var(--text-muted); font-size: 0.85rem; }

input[type="file"] { display: none; }

/* ── Preview ── */
.preview-section {
  margin-bottom: 32px;
}
.preview-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
}
.preview-card img {
  width: 100%;
  max-height: 400px;
  object-fit: contain;
  background: #000;
}
.preview-info {
  padding: 12px 16px;
  color: var(--text-muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--border);
}

/* ── Workspace ── */
.section-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 16px;
  color: var(--text);
}

/* ── Palette Grid ── */
.palette-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 12px;
  margin-bottom: 32px;
}
.palette-card {
  background: var(--bg-card);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  padding: 14px;
  cursor: pointer;
  transition: var(--transition);
}
.palette-card:hover { border-color: var(--accent); transform: translateY(-2px); }
.palette-card.selected {
  border-color: var(--accent);
  box-shadow: 0 0 0 1px var(--accent);
}
.palette-colors {
  display: flex;
  gap: 4px;
  margin-bottom: 10px;
}
.color-swatch {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  display: inline-block;
  border: 2px solid var(--bg);
  box-shadow: 0 1px 3px rgba(0,0,0,0.2);
}
.palette-name { font-weight: 600; font-size: 0.9rem; margin-bottom: 2px; }
.palette-desc { color: var(--text-muted); font-size: 0.78rem; }

/* ── Algorithm Cards ── */
.algorithm-cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 12px;
  margin-bottom: 32px;
}
.algo-card {
  background: var(--bg-card);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 6px;
}
.algo-card:hover { border-color: var(--accent); transform: translateY(-2px); }
.algo-card.selected {
  border-color: var(--accent);
  box-shadow: 0 0 0 1px var(--accent);
}
.algo-icon { font-size: 1.8rem; }
.algo-name { font-weight: 600; font-size: 0.9rem; }
.algo-desc { color: var(--text-muted); font-size: 0.75rem; }

/* ── Advanced Settings ── */
.advanced-toggle {
  display: flex;
  align-items: center;
  gap: 8px;
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 0.9rem;
  margin-bottom: 12px;
  padding: 4px 0;
}
.advanced-toggle::before {
  content: "▶";
  font-size: 0.7rem;
  transition: transform var(--transition);
}
.advanced-toggle.open::before { transform: rotate(90deg); }

.advanced-panel {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}
.setting-row {
  display: flex;
  align-items: center;
  gap: 12px;
}
.setting-row label {
  min-width: 140px;
  font-size: 0.85rem;
  color: var(--text-muted);
}
.setting-range {
  flex: 1;
  accent-color: var(--accent);
}
.setting-value {
  min-width: 40px;
  text-align: right;
  font-size: 0.85rem;
  font-weight: 600;
}

/* ── Colorize Button ── */
.colorize-action {
  text-align: center;
  margin-bottom: 40px;
}
.btn-colorize {
  background: var(--accent);
  color: #fff;
  border: none;
  padding: 14px 48px;
  font-size: 1.1rem;
  font-weight: 600;
  border-radius: var(--radius);
  cursor: pointer;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 10px;
}
.btn-colorize:hover:not(:disabled) { background: var(--accent-hover); transform: translateY(-1px); }
.btn-colorize:disabled { opacity: 0.6; cursor: not-allowed; }

.spinner {
  width: 20px;
  height: 20px;
  border: 2px solid rgba(255,255,255,0.3);
  border-top-color: #fff;
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ── Result Section ── */
.result-section {
  margin-bottom: 40px;
}
.result-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

/* Before/After Slider */
.before-after-container {
  position: relative;
  width: 100%;
  aspect-ratio: 16/10;
  overflow: hidden;
  cursor: ew-resize;
  background: #000;
}
.before-after-container img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: contain;
}
.ba-before {
  z-index: 2;
  clip-path: inset(0 50% 0 0);
}
.ba-after { z-index: 1; }
.ba-slider {
  position: absolute;
  top: 0;
  left: 50%;
  width: 3px;
  height: 100%;
  background: var(--accent);
  z-index: 10;
  cursor: ew-resize;
}
.ba-slider::before {
  content: "◀ ▶";
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: var(--accent);
  color: #fff;
  padding: 6px 8px;
  border-radius: 20px;
  font-size: 0.7rem;
  white-space: nowrap;
  letter-spacing: 2px;
}
.ba-labels {
  position: absolute;
  bottom: 12px;
  left: 0;
  right: 0;
  display: flex;
  justify-content: space-between;
  padding: 0 16px;
  z-index: 5;
  pointer-events: none;
}
.ba-label {
  background: rgba(0,0,0,0.6);
  color: #fff;
  padding: 4px 10px;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 600;
}

.result-stats {
  padding: 12px 16px;
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  font-size: 0.85rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
}

.result-actions {
  padding: 12px 16px;
  display: flex;
  gap: 10px;
  border-top: 1px solid var(--border);
}
.btn {
  padding: 8px 20px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--text);
  cursor: pointer;
  font-size: 0.85rem;
  font-weight: 500;
  transition: var(--transition);
}
.btn:hover { background: var(--bg-hover); }
.btn-primary {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}
.btn-primary:hover { background: var(--accent-hover); }

/* ── History ── */
.history-section {
  margin-bottom: 48px;
}
.history-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}
.history-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 12px;
}
.history-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  cursor: pointer;
  transition: var(--transition);
}
.history-card:hover { border-color: var(--accent); transform: translateY(-2px); }
.history-card img {
  width: 100%;
  aspect-ratio: 1;
  object-fit: cover;
}
.history-info {
  padding: 8px;
  display: flex;
  justify-content: space-between;
  font-size: 0.72rem;
  color: var(--text-muted);
}
.empty-state {
  color: var(--text-muted);
  text-align: center;
  padding: 32px;
  font-size: 0.9rem;
}

/* ── Toast ── */
#toast-container {
  position: fixed;
  top: 80px;
  right: 20px;
  z-index: 1000;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.toast {
  padding: 12px 20px;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  transform: translateX(120%);
  transition: transform 0.3s ease;
  max-width: 320px;
}
.toast.show { transform: translateX(0); }
.toast-success { border-left: 3px solid var(--success); }
.toast-error { border-left: 3px solid var(--error); }
.toast-info { border-left: 3px solid var(--accent); }

/* ── Footer ── */
footer {
  text-align: center;
  padding: 24px 0;
  color: var(--text-muted);
  font-size: 0.8rem;
  border-top: 1px solid var(--border);
}

/* ── Hidden Utility ── */
.hidden { display: none !important; }

/* ── Responsive ── */
@media (max-width: 640px) {
  .hero h1 { font-size: 1.6rem; }
  .hero p { font-size: 0.95rem; }
  .palette-grid { grid-template-columns: 1fr 1fr; }
  .algorithm-cards { grid-template-columns: 1fr 1fr; }
  .upload-zone { padding: 32px 16px; }
  .btn-colorize { width: 100%; justify-content: center; }
  .result-stats { flex-direction: column; gap: 4px; }
  .result-actions { flex-direction: column; }
  .result-actions .btn { width: 100%; text-align: center; }
  .setting-row { flex-direction: column; align-items: stretch; gap: 4px; }
  .setting-row label { min-width: auto; }
}