:root {
  --color-text: #111;
  --color-muted: #666;
  --color-border: #ccc;
  --color-bg: #fff;
  --color-focus: #0066cc;
  --radius: 4px;
}
/* touch-action: manipulation removes 300ms tap delay on touch; no effect on mouse */
html { touch-action: manipulation; }
body {
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, Arial, sans-serif;
  margin: 0;
  color: var(--color-text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-tap-highlight-color: transparent;
}
.app-header {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 6px 10px;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg);
  flex-wrap: wrap;
}
.app-header .status-text { font-size: 13px; color: var(--color-muted); flex: 1; min-width: 120px; }
.app-name { font-size: 16px; font-weight: 600; color: var(--color-text); margin-right: 8px; }
.app-header .bvlab-link {
  font-size: 13px;
  color: var(--color-muted);
  text-decoration: none;
}
.app-header .bvlab-link:hover { color: var(--color-focus); text-decoration: underline; }
.app-header .header-tutorial-link { margin-left: auto; }
.app-body {
  flex: 1;
  min-height: 0;
  display: flex;
  flex-direction: column;
  padding: 6px;
}
h2.tab-title { margin: 0 0 6px; font-size: 13px; font-weight: 600; }
.controls {
  display: flex;
  flex-direction: column;
  gap: 6px;
  align-items: stretch;
  margin-bottom: 6px;
  min-width: 0;
}
.control-value-below {
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.controls label {
  flex-direction: row;
  flex-wrap: wrap;
  min-width: 0;
  min-height: 44px;
  align-items: center;
}
.controls label input[type="range"] {
  flex: 1 1 80px;
  min-width: 70px;
  max-width: 100%;
}
label {
  font-size: 13px;
  display: flex;
  align-items: center;
  gap: 8px;
}
input[type="number"],
input[type="range"],
select {
  padding: 4px 6px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-sizing: border-box;
}
input:focus-visible,
select:focus-visible,
button:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}
button {
  padding: 8px 12px;
  min-height: 44px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-bg);
  cursor: pointer;
  font-size: 12px;
}
#computeBtn {
  min-width: 120px;
  background: #0066cc;
  color: #ffffff;
  border-color: #0053a3;
}
#computeBtn:hover:not(:disabled) {
  background: #0053a3;
}
#computeBtn:disabled {
  opacity: 0.7;
  background: #9bbce0;
  border-color: #9bbce0;
  color: #f4f7fb;
}
button:hover:not(:disabled) {
  background: #f5f5f5;
}
button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}
.canvas-tabs { flex: 1; display: flex; flex-direction: column; min-height: 0; }
.canvas-tab-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 3px;
  margin-bottom: 6px;
}
.canvas-tab-bar .tab-bar-label {
  font-size: 13px;
  color: var(--color-muted);
  margin-right: 6px;
}
.canvas-tab-bar button {
  padding: 8px 12px;
  min-height: 44px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-bg);
  cursor: pointer;
  font-size: 11px;
}
.canvas-tab-bar button:hover { background: #f5f5f5; }
.canvas-tab-bar button.active { background: #e8f4fc; font-weight: 600; }
.canvas-tab-panels { flex: 1; min-height: 0; border: 1px solid var(--color-border); border-radius: var(--radius); background: var(--color-bg); overflow: hidden; display: flex; flex-direction: row; }
.tab-panels-left {
  width: 240px;
  flex-shrink: 0;
  border-left: 1px solid var(--color-border);
  overflow-y: auto;
  overflow-x: hidden;
  -webkit-overflow-scrolling: touch;
  transition: width 0.2s, overflow 0.2s;
}
.tab-panels-left.collapsed {
  width: 0;
  min-width: 0;
  max-width: 0;
  flex: 0 0 0;
  overflow: hidden;
  border-left: none;
  padding: 0;
}
.tab-panels-left.collapsed .canvas-tab-panel {
  display: none !important;
}
.canvas-tab-bar .tab-settings-toggle {
  margin-left: auto;
  padding: 8px 10px;
  min-width: 44px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-bg);
  cursor: pointer;
  font-size: 14px;
  color: var(--color-muted);
}
.canvas-tab-bar .tab-settings-toggle:hover { background: #f5f5f5; color: var(--color-text); }
.canvas-tab-panel { display: none; padding: 8px; min-width: 0; }
.canvas-tab-panel.active { display: block; }
.zoom-viewport {
  flex: 1;
  min-width: 0;
  min-height: 0;
  overflow: hidden;
  position: relative;
  cursor: grab;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #eaeaea;
  user-select: none;
  -webkit-user-select: none;
}
/* Prevent browser scroll/zoom on touch; no effect on mouse */
@media (hover: none) and (pointer: coarse) {
  .zoom-viewport { touch-action: none; }
}
.canvas-overlay {
  position: absolute;
  top: 8px;
  left: 8px;
  z-index: 10;
  pointer-events: none;
  display: none;
}
.canvas-overlay.visible {
  display: block;
}
.canvas-overlay .overlay-content {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 8px;
  background: rgba(255,255,255,0.95);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: 0 1px 4px rgba(0,0,0,0.1);
  pointer-events: auto;
  touch-action: manipulation;
}
.canvas-overlay .overlay-mode-bar {
  display: flex;
  gap: 4px;
}
.canvas-overlay .overlay-mode-btn {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  padding: 0;
  margin: 0;
  cursor: pointer;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-bg);
}
.canvas-overlay .overlay-mode-btn:first-child { border-radius: var(--radius) 0 0 var(--radius); }
.canvas-overlay .overlay-mode-btn:last-child { border-radius: 0 var(--radius) var(--radius) 0; }
.canvas-overlay .overlay-mode-btn:not(:first-child) { margin-left: -1px; }
.canvas-overlay .overlay-mode-btn:hover { background: #f5f5f5; }
.canvas-overlay .overlay-mode-btn:has(input:checked) { background: #e8f4fc; font-weight: 600; }
.canvas-overlay .overlay-mode-btn input { position: absolute; width: 0; height: 0; opacity: 0; }
.canvas-overlay .overlay-mode-btn .bi { font-size: 1.25rem; }
.canvas-overlay .overlay-extras {
  display: none;
  flex-direction: column;
  gap: 4px;
}
.canvas-overlay .overlay-extras.visible {
  display: flex;
}
.canvas-overlay .overlay-btn {
  padding: 8px 12px;
  font-size: 11px;
  min-width: 56px;
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.canvas-overlay .overlay-btn.active {
  background: #e8f4fc;
  font-weight: 600;
}
.canvas-overlay .overlay-btn.sample-warn::after {
  content: " !";
  color: #c00;
  font-weight: 600;
  margin-left: 2px;
}
.overlay-clear-row {
  display: flex;
  gap: 4px;
}
.overlay-clear-row .overlay-btn-half {
  flex: 1;
  min-width: 0;
  padding: 8px 6px;
  font-size: 10px;
  min-height: 44px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-bg);
  cursor: pointer;
}
.overlay-clear-row .overlay-btn-half:hover { background: #f5f5f5; }
.overlay-clear-row .overlay-btn-half.active { background: #e8f4fc; font-weight: 600; }
.canvas-overlay .overlay-brush {
  display: flex;
  align-items: center;
  gap: 4px;
  font-size: 11px;
  margin-top: 2px;
}
.canvas-overlay .overlay-brush input[type="range"] {
  width: 60px;
  padding: 0;
}
.zoom-viewport:active { cursor: grabbing; }
.zoom-viewport .zoom-content {
  position: absolute;
  left: 50%;
  top: 50%;
  transform-origin: 0 0;
  will-change: transform;
}
.zoom-viewport .canvas-stack {
  position: relative;
  width: 1px;
  height: 1px;
}
.zoom-viewport .canvas-layer {
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  visibility: hidden;
}
.zoom-viewport .canvas-layer.visible { pointer-events: auto; visibility: visible; }
.zoom-viewport .canvas-layer canvas { display: block; }
canvas {
  border: 1px solid var(--color-border);
  background: var(--color-bg);
  max-width: 100%;
  height: auto;
  display: block;
}
#can_mask_overlay {
  background: transparent;
  border-color: transparent;
  opacity: 0.35;
}
.small {
  font-size: 12px;
  color: var(--color-muted);
}
.section-heading {
  margin-top: 8px;
  margin-bottom: 2px;
  text-align: left;
}
.section-heading:first-child { margin-top: 0; }

.img-info {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.samples-info {
  font-size: 13px;
}
.canvas-tab-panel .small {
  overflow-wrap: break-word;
  word-wrap: break-word;
}
.upload-label {
  font-size: 12px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  cursor: pointer;
  padding: 6px 10px;
  min-height: 44px;
  box-sizing: border-box;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-bg);
}
.upload-label:hover {
  background: #f5f5f5;
}
.upload-label input[type="file"] {
  width: 0.1px;
  height: 0.1px;
  opacity: 0;
  overflow: hidden;
  position: absolute;
}
.download-buttons {
  flex-direction: column;
  gap: 6px;
}
.how-to-use {
  margin-top: 6px;
  line-height: 1.5;
}
.how-to-use p {
  margin: 0 0 6px;
  font-size: 12px;
  color: var(--color-muted);
}
.how-to-use p:last-child { margin-bottom: 0; }
.how-to-use .bi {
  font-size: 1em;
  vertical-align: -0.15em;
}
.tab-controls {
  margin-top: 6px;
}
.tab-meta {
  margin-top: 6px;
}