/* ==============================
   Design Tokens
   ============================== */
:root {
  --bg-primary: #0f0f14;
  --bg-secondary: #1a1a24;
  --bg-tertiary: #24243a;
  --bg-hover: #2e2e48;
  --text-primary: #e8e8f0;
  --text-secondary: #9898b0;
  --text-muted: #68688a;
  --accent: #7c6aef;
  --accent-hover: #9080ff;
  --accent-glow: rgba(124, 106, 239, 0.25);
  --success: #4ae68a;
  --border: rgba(255, 255, 255, 0.06);
  --border-active: rgba(124, 106, 239, 0.4);
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.35);
  --transition: 0.2s cubic-bezier(0.4, 0, 0.2, 1);

  --checker-size: 12px;
  --checker-light: #3a3a50;
  --checker-dark: #2a2a40;
}

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

body {
  font-family: 'Segoe UI', 'Yu Gothic UI', 'Noto Sans JP', sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ==============================
   App Layout
   ============================== */
.app {
  max-width: 1200px;
  margin: 0 auto;
  padding: 32px 24px 64px;
}

/* ==============================
   Header
   ============================== */
.header {
  text-align: center;
  margin-bottom: 40px;
}

.header h1 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  background: linear-gradient(135deg, var(--accent), #c084fc, var(--accent));
  background-size: 200% 200%;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: shimmer 4s ease-in-out infinite;
}

@keyframes shimmer {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

.subtitle {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-top: 6px;
}

/* ==============================
   Drop Zone
   ============================== */
.drop-zone {
  border: 2px dashed var(--border-active);
  border-radius: var(--radius-lg);
  padding: 60px 32px;
  text-align: center;
  cursor: pointer;
  transition: all var(--transition);
  background: var(--bg-secondary);
  position: relative;
}

.drop-zone:hover,
.drop-zone.drag-over {
  border-color: var(--accent);
  background: var(--bg-tertiary);
  box-shadow: 0 0 40px var(--accent-glow);
}

.drop-zone.drag-over {
  transform: scale(1.01);
}

.drop-zone__icon {
  width: 56px;
  height: 56px;
  color: var(--accent);
  margin-bottom: 16px;
  opacity: 0.7;
  transition: opacity var(--transition);
}

.drop-zone:hover .drop-zone__icon {
  opacity: 1;
}

.drop-zone__text {
  font-size: 1.1rem;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.drop-zone__hint {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* ==============================
   Controls
   ============================== */
.controls {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px 32px;
  margin-top: 24px;
  display: grid;
  gap: 20px;
}

.control-group label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 6px;
}

.control-value {
  font-family: 'Consolas', 'Courier New', monospace;
  font-size: 0.85rem;
  color: var(--accent);
  background: var(--bg-tertiary);
  padding: 1px 8px;
  border-radius: 4px;
}

/* Range Slider */
input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  background: var(--bg-tertiary);
  border-radius: 3px;
  outline: none;
  cursor: pointer;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 18px;
  height: 18px;
  background: var(--accent);
  border-radius: 50%;
  box-shadow: 0 0 8px var(--accent-glow);
  transition: transform var(--transition);
}

input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.2);
}

input[type="range"]::-moz-range-thumb {
  width: 18px;
  height: 18px;
  background: var(--accent);
  border-radius: 50%;
  border: none;
  box-shadow: 0 0 8px var(--accent-glow);
}

.control-hints {
  display: flex;
  justify-content: space-between;
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 4px;
}

/* Buttons */
.control-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 8px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 22px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  font-family: inherit;
}

.btn--primary {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border);
}

.btn--primary:hover {
  background: var(--bg-hover);
  border-color: var(--border-active);
}

.btn--accent {
  background: var(--accent);
  color: #fff;
}

.btn--accent:hover {
  background: var(--accent-hover);
  box-shadow: 0 0 20px var(--accent-glow);
}

.btn--secondary {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--border);
}

.btn--secondary:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}

.btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
  pointer-events: none;
}

/* ==============================
   Preview Area
   ============================== */
.preview-area {
  margin-top: 24px;
}

.preview-container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

.preview-panel {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.preview-panel__title {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.preview-panel__canvas-wrap {
  padding: 16px;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 200px;
}

.preview-panel__canvas-wrap canvas {
  max-width: 100%;
  max-height: 70vh;
  border-radius: var(--radius-sm);
}

/* Checkerboard Pattern */
.checkerboard {
  background-image:
    linear-gradient(45deg, var(--checker-dark) 25%, transparent 25%),
    linear-gradient(-45deg, var(--checker-dark) 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, var(--checker-dark) 75%),
    linear-gradient(-45deg, transparent 75%, var(--checker-dark) 75%);
  background-size: calc(var(--checker-size) * 2) calc(var(--checker-size) * 2);
  background-position:
    0 0,
    0 var(--checker-size),
    var(--checker-size) calc(-1 * var(--checker-size)),
    calc(-1 * var(--checker-size)) 0;
  background-color: var(--checker-light);
}

/* Zoom Viewport */
.result-viewport {
  overflow: hidden;
  position: relative;
  cursor: grab;
}

.result-viewport:active {
  cursor: grabbing;
}

.result-viewport.result-canvas--clickable {
  cursor: crosshair;
}

.selection-rect {
  position: absolute;
  border: 2px solid rgba(100, 160, 255, 0.9);
  background: rgba(100, 160, 255, 0.15);
  pointer-events: none;
  z-index: 10;
}

.result-viewport canvas {
  transform-origin: 0 0;
  will-change: transform;
}

.zoom-level {
  font-size: 0.7rem;
  font-weight: 400;
  color: var(--accent);
  font-family: 'Consolas', 'Courier New', monospace;
  margin-left: 8px;
}

.zoom-controls {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 8px 16px;
  border-top: 1px solid var(--border);
}

.zoom-hint {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.btn-mini {
  font-size: 0.75rem;
  padding: 4px 12px;
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  border: 1px solid var(--border);
  border-radius: 4px;
  cursor: pointer;
  font-family: inherit;
  transition: all var(--transition);
}

.btn-mini:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
}

/* Image Info */
.image-info {
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 12px;
}

/* ==============================
   Processing Overlay
   ============================== */
.processing-overlay {
  position: fixed;
  inset: 0;
  background: rgba(15, 15, 20, 0.85);
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 20px;
  z-index: 1000;
  backdrop-filter: blur(6px);
}

.processing-spinner {
  width: 48px;
  height: 48px;
  border: 3px solid var(--bg-tertiary);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.processing-text {
  color: var(--text-secondary);
  font-size: 1rem;
}

/* Background Color Row */
.bg-color-row {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 6px;
}

.bg-color-swatch {
  width: 32px;
  height: 32px;
  border-radius: 6px;
  border: 2px solid var(--border-active);
  cursor: pointer;
  flex-shrink: 0;
  position: relative;
  overflow: hidden;
  background: #ffffff;
}

.bg-color-input {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: none;
  padding: 0;
  cursor: pointer;
  opacity: 0;
}

/* Mode Toggle */
.mode-toggle {
  display: flex;
  gap: 8px;
  margin-bottom: 4px;
}

.mode-btn {
  flex: 1;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  font-family: inherit;
  text-align: center;
}

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

.mode-btn:hover:not(.active) {
  background: var(--bg-hover);
  color: var(--text-primary);
}

.mode-section {
  display: contents;
}

.mode-section.hidden > * {
  display: none !important;
}

/* AI Select */
.ai-select {
  width: 100%;
  padding: 8px 12px;
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.88rem;
  font-family: inherit;
  cursor: pointer;
  margin-top: 4px;
  outline: none;
  transition: border-color var(--transition);
}

.ai-select:focus { border-color: var(--border-active); }

/* Checkbox label */
.checkbox-label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
  cursor: pointer;
  user-select: none;
}

.checkbox-label input[type="checkbox"] {
  width: 16px;
  height: 16px;
  accent-color: var(--accent);
  cursor: pointer;
}

.alpha-matting-options {
  margin-top: 14px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding-left: 24px;
  border-left: 2px solid var(--border-active);
}

.control-subgroup label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-bottom: 4px;
}

/* AI server row */
.ai-server-row {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.btn-mini--accent {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.btn-mini--accent:hover {
  background: var(--accent-hover);
}

/* AI status */
.ai-status {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 4px;
}

.ai-status.ok { color: var(--success); }
.ai-status.error { color: #ff6b6b; }

.ai-log {
  margin-top: 8px;
  padding: 8px 10px;
  background: #0a0a12;
  border: 1px solid #2a2a45;
  border-radius: 6px;
  font-size: 0.72rem;
  font-family: monospace;
  color: #888;
  max-height: 120px;
  overflow-y: auto;
  white-space: pre-wrap;
  word-break: break-all;
  line-height: 1.5;
}

/* Click Remove Mode */
.btn--secondary.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.btn--secondary.active:hover {
  background: var(--accent-hover);
}

.click-remove-hint {
  font-size: 0.7rem;
  font-weight: 400;
  color: var(--accent);
  animation: pulse 1.5s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

.result-canvas--clickable {
  cursor: crosshair;
}

/* ==============================
   Utilities
   ============================== */
.hidden {
  display: none !important;
}

/* ==============================
   Responsive
   ============================== */
@media (max-width: 768px) {
  .app {
    padding: 20px 16px 48px;
  }

  .header h1 {
    font-size: 1.5rem;
  }

  .preview-container {
    grid-template-columns: 1fr;
  }

  .drop-zone {
    padding: 40px 20px;
  }

  .control-actions {
    flex-direction: column;
  }

  .btn {
    justify-content: center;
  }
}