/* ==========================================
   DESIGN TOKENS
   ========================================== */

:root {
  /* Type scale */
  --text-xs:   clamp(0.75rem,  0.7rem  + 0.25vw, 0.875rem);
  --text-sm:   clamp(0.875rem, 0.8rem  + 0.35vw, 1rem);
  --text-base: clamp(1rem,     0.95rem + 0.25vw, 1.125rem);
  --text-lg:   clamp(1.125rem, 1rem    + 0.75vw, 1.5rem);
  --text-xl:   clamp(1.5rem,   1.2rem  + 1.25vw, 2.25rem);

  /* Spacing */
  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --space-4:  1rem;
  --space-5:  1.25rem;
  --space-6:  1.5rem;
  --space-8:  2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;

  /* Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;

  /* Transitions */
  --transition-interactive: 180ms cubic-bezier(0.16, 1, 0.3, 1);

  /* Fonts */
  --font-body: 'General Sans', 'Helvetica Neue', sans-serif;
  --font-mono: 'JetBrains Mono', 'Consolas', monospace;

  /* Content widths */
  --content-wide: 1200px;
}

/* ==========================================
   DARK THEME (Default)
   ========================================== */

:root, [data-theme="dark"] {
  --color-bg:             #0e0e10;
  --color-surface:        #18181b;
  --color-surface-2:      #1e1e22;
  --color-surface-offset: #141416;
  --color-border:         #2a2a2e;
  --color-border-hover:   #3a3a3f;
  --color-text:           #e4e4e7;
  --color-text-muted:     #8b8b92;
  --color-text-faint:     #52525a;
  --color-primary:        #6ee7b7;
  --color-primary-hover:  #34d399;
  --color-primary-active: #10b981;
  --color-primary-dim:    rgba(110, 231, 183, 0.1);
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.4);
  --shadow-lg: 0 12px 32px rgba(0,0,0,0.5);
}

/* ==========================================
   LIGHT THEME
   ========================================== */

[data-theme="light"] {
  --color-bg:             #f4f4f5;
  --color-surface:        #ffffff;
  --color-surface-2:      #fafafa;
  --color-surface-offset: #e4e4e7;
  --color-border:         #d4d4d8;
  --color-border-hover:   #a1a1aa;
  --color-text:           #18181b;
  --color-text-muted:     #71717a;
  --color-text-faint:     #a1a1aa;
  --color-primary:        #059669;
  --color-primary-hover:  #047857;
  --color-primary-active: #065f46;
  --color-primary-dim:    rgba(5, 150, 105, 0.08);
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
  --shadow-lg: 0 12px 32px rgba(0,0,0,0.12);
}

@media (prefers-color-scheme: light) {
  :root:not([data-theme]) {
    --color-bg:             #f4f4f5;
    --color-surface:        #ffffff;
    --color-surface-2:      #fafafa;
    --color-surface-offset: #e4e4e7;
    --color-border:         #d4d4d8;
    --color-border-hover:   #a1a1aa;
    --color-text:           #18181b;
    --color-text-muted:     #71717a;
    --color-text-faint:     #a1a1aa;
    --color-primary:        #059669;
    --color-primary-hover:  #047857;
    --color-primary-active: #065f46;
    --color-primary-dim:    rgba(5, 150, 105, 0.08);
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.06);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
    --shadow-lg: 0 12px 32px rgba(0,0,0,0.12);
  }
}

/* ==========================================
   LAYOUT
   ========================================== */

body {
  display: flex;
  flex-direction: column;
}

.app-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-3) var(--space-6);
}

.header-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo-group {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.logo-icon {
  flex-shrink: 0;
}

.logo-text {
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--color-text);
}

[data-theme-toggle] {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
}

[data-theme-toggle]:hover {
  background: var(--color-surface-2);
  color: var(--color-text);
}

.app-main {
  flex: 1;
  max-width: var(--content-wide);
  width: 100%;
  margin: 0 auto;
  padding: var(--space-6);
}

.app-footer {
  text-align: center;
  padding: var(--space-4) var(--space-6);
  border-top: 1px solid var(--color-border);
}

.app-footer a {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  text-decoration: none;
}

.app-footer a:hover {
  color: var(--color-text-muted);
}

/* ==========================================
   UPLOAD SECTION
   ========================================== */

.upload-section {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 60vh;
}


.drop-zone {
  width: 100%;
  max-width: 520px;
  padding: var(--space-16) var(--space-8);
  border: 2px dashed var(--color-border);
  border-radius: var(--radius-xl);
  text-align: center;
  cursor: pointer;
  transition: border-color var(--transition-interactive),
              background var(--transition-interactive);
}

.drop-zone:hover,
.drop-zone.drag-over {
  border-color: var(--color-primary);
  background: var(--color-primary-dim);
}

.drop-icon {
  margin: 0 auto var(--space-4);
  color: var(--color-text-faint);
}

.drop-zone:hover .drop-icon,
.drop-zone.drag-over .drop-icon {
  color: var(--color-primary);
}

.drop-text {
  font-size: var(--text-base);
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: var(--space-2);
}

.drop-hint {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
}

/* ==========================================
   EDITOR SECTION
   ========================================== */

.editor-section {
  animation: fadeIn 300ms ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.editor-layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: var(--space-6);
  align-items: start;
}

@media (max-width: 768px) {
  .editor-layout {
    grid-template-columns: 1fr;
  }
}

/* ==========================================
   CONTROLS PANEL
   ========================================== */

.controls-panel {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  display: flex;
  flex-direction: column;
  gap: var(--space-5);
  position: sticky;
  top: calc(52px + var(--space-6));
}

@media (max-width: 768px) {
  .controls-panel {
    position: static;
    order: 2;
  }
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.control-label {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

/* Slider */
.slider-row {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.slider {
  flex: 1;
  -webkit-appearance: none;
  appearance: none;
  height: 6px;
  border-radius: var(--radius-full);
  background: var(--color-border);
  outline: none;
}

.slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--color-primary);
  cursor: pointer;
  border: 2px solid var(--color-bg);
  box-shadow: var(--shadow-sm);
}

.slider::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--color-primary);
  cursor: pointer;
  border: 2px solid var(--color-bg);
  box-shadow: var(--shadow-sm);
}

.slider-value {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-primary);
  min-width: 3.5ch;
  text-align: right;
  font-variant-numeric: tabular-nums;
}

/* Preset buttons */
.presets-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-2);
}

.preset-btn {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  padding: var(--space-2) var(--space-1);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
  text-align: center;
}

.preset-btn:hover {
  border-color: var(--color-border-hover);
  color: var(--color-text);
}

.preset-btn.active {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-dim);
}

/* Cleanup buttons */
.cleanup-options {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-2);
}

.cleanup-btn {
  font-size: var(--text-xs);
  padding: var(--space-2) var(--space-1);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
  text-align: center;
}

.cleanup-btn:hover {
  border-color: var(--color-border-hover);
  color: var(--color-text);
}

.cleanup-btn.active {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-dim);
}

.control-hint {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  line-height: 1.4;
}

/* Palette buttons */
.palette-options {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-2);
}

.palette-btn {
  font-size: var(--text-xs);
  padding: var(--space-2) var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
  text-align: center;
}

.palette-btn:hover {
  border-color: var(--color-border-hover);
  color: var(--color-text);
}

.palette-btn.active {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-dim);
}

/* Toggle button */
.toggle-row {
  display: flex;
}

.toggle-btn {
  font-size: var(--text-xs);
  padding: var(--space-2) var(--space-4);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
}

.toggle-btn:hover {
  border-color: var(--color-border-hover);
  color: var(--color-text);
}

.toggle-btn[aria-pressed="true"] {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-dim);
}

/* Result info */
.result-info {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  font-variant-numeric: tabular-nums;
}

/* Action buttons */
.action-buttons {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  margin-top: var(--space-2);
}

.btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: 600;
}

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

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

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

.btn-secondary:hover {
  border-color: var(--color-border-hover);
  color: var(--color-text);
}

/* ==========================================
   CANVAS AREA
   ========================================== */

.canvas-area {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

@media (max-width: 768px) {
  .canvas-area {
    order: 1;
  }
}

.canvas-tabs {
  display: flex;
  gap: var(--space-1);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-1);
  width: fit-content;
}

.tab-btn {
  font-size: var(--text-xs);
  font-weight: 500;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
}

.tab-btn:hover {
  color: var(--color-text);
}

.tab-btn.active {
  background: var(--color-primary-dim);
  color: var(--color-primary);
}

.canvas-wrapper {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-4);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 400px;
  overflow: hidden;
  position: relative;
}

.canvas-wrapper canvas {
  max-width: 100%;
  max-height: 70vh;
  image-rendering: pixelated;
  image-rendering: -moz-crisp-edges;
  image-rendering: crisp-edges;
  border-radius: var(--radius-sm);
}

/* ==========================================
   COMPARE VIEW
   ========================================== */

.compare-container {
  position: relative;
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.compare-container canvas {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  max-width: 100%;
  max-height: 70vh;
}

#compareOriginal {
  clip-path: inset(0 50% 0 0);
  z-index: 2;
}

#compareResult {
  z-index: 1;
}

.compare-slider {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 50%;
  z-index: 10;
  cursor: col-resize;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.compare-line {
  width: 2px;
  flex: 1;
  background: var(--color-primary);
}

.compare-handle {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--color-primary);
  color: var(--color-bg);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  box-shadow: var(--shadow-md);
}

/* ==========================================
   EDITOR TOOLBAR
   ========================================== */

.editor-toolbar {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  flex-wrap: wrap;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-2) var(--space-3);
}

.tool-group {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.tool-group + .tool-group {
  padding-left: var(--space-3);
  border-left: 1px solid var(--color-border);
}

.tool-btn {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  font-size: var(--text-xs);
  padding: var(--space-1) var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
  white-space: nowrap;
}

.tool-btn:hover {
  border-color: var(--color-border-hover);
  color: var(--color-text);
}

.tool-btn.active {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-dim);
}

.tool-btn svg { flex-shrink: 0; }

.tool-btn-small {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  font-size: var(--text-xs);
  padding: var(--space-1) var(--space-2);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
  white-space: nowrap;
}

.tool-btn-small:hover {
  border-color: var(--color-border-hover);
  color: var(--color-text);
}

.color-picker-row {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.tool-label {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
}

.color-swatch {
  width: 20px;
  height: 20px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  flex-shrink: 0;
}

.color-input {
  width: 28px;
  height: 22px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: 0;
  cursor: pointer;
  background: none;
}

.color-input::-webkit-color-swatch-wrapper { padding: 1px; }
.color-input::-webkit-color-swatch { border: none; border-radius: 2px; }

.edit-count {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  font-variant-numeric: tabular-nums;
}
}