.tool-header {
  padding: var(--space-10) 0 var(--space-6);
  background: linear-gradient(180deg, var(--color-light-blue) 0%, var(--color-white) 100%);
  border-bottom: 1px solid var(--color-border);
}
.tool-header h1 { font-size: var(--text-4xl); margin-bottom: var(--space-3); }
.tool-header p { font-size: var(--text-lg); color: var(--color-dark-muted); max-width: 760px; }

.tool-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 320px;
  gap: var(--space-8);
  padding: var(--space-10) 0;
}
.tool-main { min-width: 0; }
.tool-sidebar { position: sticky; top: calc(var(--header-height) + var(--space-4)); align-self: start; }

.tool-panel {
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  margin-bottom: var(--space-6);
}
.tool-panel-title {
  font-size: var(--text-lg);
  font-weight: var(--weight-semibold);
  color: var(--color-dark);
  margin-bottom: var(--space-4);
}

.tool-content {
  padding: var(--space-10) 0;
  max-width: 820px;
  font-size: 1.0625rem;
  line-height: 1.75;
  color: var(--color-dark-muted);
}
.tool-content h2 { color: var(--color-dark); font-size: var(--text-2xl); margin-top: var(--space-8); margin-bottom: var(--space-3); }
.tool-content h3 { color: var(--color-dark); font-size: var(--text-xl); margin-top: var(--space-6); margin-bottom: var(--space-3); }
.tool-content p { margin-bottom: var(--space-4); }
.tool-content ul, .tool-content ol { padding-left: var(--space-6); margin-bottom: var(--space-4); }
.tool-content a { color: var(--color-primary); text-decoration: underline; text-underline-offset: 2px; }
.tool-content a:hover { color: var(--color-primary-hover); }

/* Color Picker layout */
.picker-wrap {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-6);
}
.picker-canvas-wrap {
  position: relative;
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: #f0f4ff;
  aspect-ratio: 1;
  cursor: crosshair;
  touch-action: none;
}
#picker-sat-val, #picker-hue, #picker-alpha {
  display: block;
  width: 100%;
  height: 100%;
  border-radius: inherit;
}
#picker-hue, #picker-alpha { height: 20px; border-radius: var(--radius-md); cursor: pointer; }
.picker-slider-wrap { margin-top: var(--space-4); }

.picker-marker {
  position: absolute;
  width: 16px;
  height: 16px;
  border: 2px solid #fff;
  border-radius: 50%;
  box-shadow: 0 0 0 1px rgba(0,0,0,.3), 0 2px 4px rgba(0,0,0,.25);
  transform: translate(-50%, -50%);
  pointer-events: none;
}

.color-preview-box {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  background: var(--color-off-white);
}
.color-preview-chip {
  height: 100px;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  margin-bottom: var(--space-4);
  display: flex;
  align-items: flex-end;
  padding: var(--space-3);
  color: #fff;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 600;
  text-shadow: 0 1px 2px rgba(0,0,0,.35);
}

.value-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--space-3); margin-bottom: var(--space-4); }
.value-row {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-2) var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
}
.value-row-label {
  font-family: var(--font-sans);
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--color-dark-subtle);
  text-transform: uppercase;
  letter-spacing: .05em;
  min-width: 40px;
}
.value-row input {
  flex: 1;
  border: 0;
  background: transparent;
  font: inherit;
  color: var(--color-dark);
  min-width: 0;
  padding: 0;
}
.value-row input:focus { outline: none; }
.value-row .copy-btn { padding: 2px 6px; min-height: 24px; font-size: 10px; }

.swatch-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(36px, 1fr));
  gap: var(--space-2);
}
.swatch-item {
  aspect-ratio: 1;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  cursor: pointer;
  transition: transform var(--transition-fast);
}
.swatch-item:hover { transform: scale(1.08); }

/* Converter */
.converter-input-group {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: var(--space-3);
  align-items: center;
  margin-bottom: var(--space-3);
}
.converter-input-group label {
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  color: var(--color-dark);
}

/* Palette */
.palette-preview { display: flex; border-radius: var(--radius-lg); overflow: hidden; height: 200px; margin-bottom: var(--space-5); }
.palette-swatch-item {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  align-items: center;
  padding: var(--space-3);
  color: #fff;
  cursor: pointer;
  transition: flex var(--transition-base);
  position: relative;
}
.palette-swatch-item:hover { flex: 1.3; }
.palette-swatch-item span {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 600;
  text-shadow: 0 1px 2px rgba(0,0,0,.4);
  padding: 2px 6px;
  border-radius: 4px;
  background: rgba(0,0,0,.25);
}

/* Gradient */
.gradient-preview {
  height: 220px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  margin-bottom: var(--space-5);
}
.gradient-stops { display: flex; flex-direction: column; gap: var(--space-3); }
.gradient-stop-row {
  display: grid;
  grid-template-columns: 40px 1fr 80px 60px 40px;
  gap: var(--space-2);
  align-items: center;
  padding: var(--space-2);
  background: var(--color-off-white);
  border-radius: var(--radius-md);
}
.gradient-stop-row input[type="color"] {
  width: 36px;
  height: 36px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: 0;
  cursor: pointer;
  background: #fff;
}
.gradient-stop-row input[type="text"],
.gradient-stop-row input[type="number"] {
  padding: 6px 8px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 13px;
  min-width: 0;
  width: 100%;
}
.gradient-stop-row .btn-icon { width: 32px; height: 32px; min-width: 32px; min-height: 32px; padding: 0; }

.gradient-preview-strip {
  position: relative;
  height: 40px;
  border-radius: var(--radius-md);
  margin-bottom: var(--space-3);
  border: 1px solid var(--color-border);
}
.gradient-stop-marker {
  position: absolute;
  top: -10px;
  width: 20px;
  height: 20px;
  border: 2px solid #fff;
  border-radius: 50%;
  box-shadow: 0 0 0 1px rgba(0,0,0,.3);
  transform: translateX(-50%);
  cursor: grab;
}

/* Contrast */
.contrast-preview {
  padding: var(--space-8);
  border-radius: var(--radius-lg);
  text-align: center;
  margin-bottom: var(--space-5);
  border: 1px solid var(--color-border);
}
.contrast-preview .preview-sample-large { font-size: 32px; font-weight: 700; margin-bottom: var(--space-3); }
.contrast-preview .preview-sample-normal { font-size: 16px; }

.contrast-ratio {
  font-size: 3rem;
  font-weight: 800;
  color: var(--color-primary);
  font-family: var(--font-mono);
  text-align: center;
  margin-bottom: var(--space-2);
}
.contrast-ratio-label { text-align: center; font-size: var(--text-sm); color: var(--color-dark-muted); margin-bottom: var(--space-5); }

.contrast-results { display: grid; grid-template-columns: 1fr 1fr; gap: var(--space-3); }
.contrast-result-item {
  padding: var(--space-4);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  text-align: center;
}
.contrast-result-item .label { font-size: var(--text-xs); color: var(--color-dark-subtle); text-transform: uppercase; letter-spacing: .05em; margin-bottom: var(--space-1); }
.contrast-result-item .status { font-size: var(--text-lg); font-weight: 700; }
.contrast-result-item.pass { border-color: var(--color-success); background: var(--color-success-light); }
.contrast-result-item.pass .status { color: var(--color-success); }
.contrast-result-item.fail { border-color: var(--color-danger); background: var(--color-danger-light); }
.contrast-result-item.fail .status { color: var(--color-danger); }

/* Image picker */
.image-drop-zone {
  border: 2px dashed var(--color-border-strong);
  border-radius: var(--radius-lg);
  padding: var(--space-10) var(--space-5);
  text-align: center;
  cursor: pointer;
  transition: border-color var(--transition-base), background var(--transition-base);
  background: var(--color-off-white);
}
.image-drop-zone:hover, .image-drop-zone.is-dragover {
  border-color: var(--color-primary);
  background: var(--color-light-blue);
}
.image-drop-zone svg { width: 48px; height: 48px; color: var(--color-primary); margin: 0 auto var(--space-3); }
.image-drop-zone-title { font-size: var(--text-lg); font-weight: 600; color: var(--color-dark); margin-bottom: var(--space-2); }
.image-drop-zone-desc { font-size: var(--text-sm); color: var(--color-dark-muted); }

.image-preview-wrap {
  position: relative;
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: #f0f4ff;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 300px;
  max-height: 600px;
}
.image-preview-wrap canvas { max-width: 100%; max-height: 600px; height: auto; cursor: crosshair; display: block; }

.extracted-palette {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(70px, 1fr));
  gap: var(--space-2);
  margin-top: var(--space-4);
}
.extracted-swatch {
  aspect-ratio: 1;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  cursor: pointer;
  position: relative;
  overflow: hidden;
  transition: transform var(--transition-fast);
}
.extracted-swatch:hover { transform: scale(1.05); }
.extracted-swatch span {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  padding: 4px;
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 600;
  text-align: center;
  color: #fff;
  background: rgba(0,0,0,.4);
}

@media (max-width: 1023px) {
  .tool-layout { grid-template-columns: 1fr; }
  .tool-sidebar { position: static; }
  .picker-wrap { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .tool-header h1 { font-size: var(--text-3xl); }
  .tool-header p { font-size: var(--text-base); }
  .tool-panel { padding: var(--space-4); }
  .value-grid { grid-template-columns: 1fr; }
  .contrast-results { grid-template-columns: 1fr; }
  .palette-preview { height: 140px; }
  .palette-swatch-item span { font-size: 10px; }
  .gradient-stop-row { grid-template-columns: 36px 1fr 60px 40px; gap: 6px; }
  .gradient-stop-row .stop-remove { display: none; }
  .converter-input-group { grid-template-columns: 100px 1fr; }
}