:root {
  --bg:        #12151a;
  --panel:     #1a1e25;
  --panel-2:   #20252d;
  --border:    #2b313c;
  --text:      #e6e9ee;
  --muted:     #8892a0;
  --accent:    #4fd1c5;
  --accent-dim:#2c7a72;
  --chan-r:    #ff6b6b;
  --chan-g:    #7ee787;
  --chan-b:    #6ea8ff;
  --chan-a:    #c9cfd8;
  --mono: 'JetBrains Mono', 'Fira Code', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --sans: 'Inter', system-ui, -apple-system, sans-serif;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  height: 100%;
  overflow: hidden; /* the app owns its own scroll regions; the page itself never scrolls */
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 13px;
  color-scheme: dark;
}

.app {
  display: grid;
  grid-template-columns: 300px 1fr;
  grid-template-rows: 100%;
  height: 100vh;
  width: 100vw;
  overflow: hidden;
}

/* ---------- Sidebar ---------- */

.sidebar {
  height: 100%;
  min-height: 0;
  background: var(--panel);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  padding: 18px 16px 32px;
}

.brand {
  display: flex;
  align-items: baseline;
  gap: 8px;
  margin-bottom: 18px;
}

.brand .mark {
  font-family: var(--mono);
  color: var(--accent);
  font-weight: 700;
  font-size: 15px;
  letter-spacing: 0.5px;
}

.brand .sub {
  color: var(--muted);
  font-size: 11px;
  font-family: var(--mono);
}

.section {
  border-top: 1px solid var(--border);
  padding: 14px 0;
}
.section:first-of-type { border-top: none; padding-top: 0; }

.section h2 {
  font-size: 10.5px;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  color: var(--muted);
  margin: 0 0 10px;
  font-weight: 600;
}

.field {
  margin-bottom: 10px;
}

.field label {
  display: block;
  font-size: 11.5px;
  color: var(--muted);
  margin-bottom: 4px;
}

.row {
  display: flex;
  gap: 8px;
}
.row .field { flex: 1; min-width: 0; }

input[type="number"],
input[type="text"],
select {
  width: 100%;
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 5px;
  padding: 6px 8px;
  font-family: var(--mono);
  font-size: 12.5px;
  outline: none;
}
input[type="number"]:focus,
input[type="text"]:focus,
select:focus {
  border-color: var(--accent);
}

input[type="file"] {
  width: 100%;
  font-size: 11.5px;
  color: var(--muted);
}

input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
}

.checkbox-row {
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--muted);
  font-size: 11.5px;
}
.checkbox-row input { accent-color: var(--accent); }

button {
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 5px;
  padding: 6px 10px;
  font-size: 11.5px;
  cursor: pointer;
  font-family: var(--sans);
}
button:hover { border-color: var(--accent); color: var(--accent); }
button.primary {
  background: var(--accent-dim);
  border-color: var(--accent-dim);
  color: #08201d;
  font-weight: 600;
}
button.primary:hover { color: #08201d; border-color: var(--accent); }

.btn-row { display: flex; gap: 8px; }
.btn-row button { flex: 1; }

/* Channel swatch toggle buttons */
.channel-group {
  display: flex;
  gap: 6px;
}
.chan-btn {
  flex: 1;
  padding: 6px 0;
  text-align: center;
  border-radius: 5px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  font-family: var(--mono);
  font-weight: 700;
  font-size: 11.5px;
  cursor: pointer;
  color: var(--muted);
}
.chan-btn[data-chan="color"] { color: var(--text); }
.chan-btn[data-chan="r"] { color: var(--chan-r); }
.chan-btn[data-chan="g"] { color: var(--chan-g); }
.chan-btn[data-chan="b"] { color: var(--chan-b); }
.chan-btn[data-chan="a"] { color: var(--chan-a); }
.chan-btn.active {
  background: var(--panel);
  border-color: currentColor;
  box-shadow: 0 0 0 1px currentColor inset;
}

.slice-readout {
  font-family: var(--mono);
  color: var(--text);
  font-size: 11.5px;
  text-align: right;
}

.warning {
  margin-top: 6px;
  font-size: 11px;
  color: #ffb454;
  font-family: var(--mono);
  line-height: 1.4;
}
.ok {
  margin-top: 6px;
  font-size: 11px;
  color: var(--accent);
  font-family: var(--mono);
}

/* ---------- Main viewer ---------- */

.viewer {
  display: flex;
  flex-direction: column;
  height: 100%;
  min-width: 0;
  min-height: 0;
}

.viewer-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 16px;
  border-bottom: 1px solid var(--border);
  background: var(--panel);
  flex-shrink: 0;
}

.viewer-toolbar .plane-tabs {
  display: flex;
  gap: 4px;
}
.plane-tab {
  padding: 5px 12px;
  border-radius: 5px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--muted);
  font-family: var(--mono);
  font-size: 11.5px;
  cursor: pointer;
}
.plane-tab.active {
  color: var(--accent);
  border-color: var(--accent-dim);
  background: rgba(79, 209, 197, 0.08);
}

.zoom-controls {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 11.5px;
}
.zoom-controls input[type="range"] { width: 110px; }

.canvas-stage {
  flex: 1;
  min-height: 0;
  min-width: 0;
  overflow: auto;
  overscroll-behavior: contain;
  display: flex;
  align-items: center;
  justify-content: center;
  /* "safe" centering keeps the image centered while it's smaller than the
     viewport, but falls back to top/left alignment (instead of clipping
     the far edge) once it's zoomed past the viewport size, so the full
     image stays reachable by panning/scrolling. */
  align-items: safe center;
  justify-content: safe center;
  background:
    linear-gradient(45deg, #23262d 25%, transparent 25%),
    linear-gradient(-45deg, #23262d 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, #23262d 75%),
    linear-gradient(-45deg, transparent 75%, #23262d 75%);
  background-size: 20px 20px;
  background-position: 0 0, 0 10px, 10px -10px, -10px 0px;
  background-color: #1a1c21;
  position: relative;
  cursor: grab;
}
.canvas-stage.panning {
  cursor: grabbing;
}

#viewCanvas {
  image-rendering: pixelated;
  image-rendering: crisp-edges;
  box-shadow: 0 0 0 1px rgba(255,255,255,0.08);
}

.empty-state {
  color: var(--muted);
  font-family: var(--mono);
  font-size: 12.5px;
  text-align: center;
  line-height: 1.7;
}
.empty-state .mark { color: var(--accent); }

.status-bar {
  border-top: 1px solid var(--border);
  background: var(--panel);
  padding: 6px 16px;
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--muted);
  display: flex;
  gap: 22px;
  white-space: nowrap;
  overflow-x: auto;
  flex-shrink: 0;
}
.status-bar span b { color: var(--text); }
.status-bar .swatch-r { color: var(--chan-r); }
.status-bar .swatch-g { color: var(--chan-g); }
.status-bar .swatch-b { color: var(--chan-b); }
.status-bar .swatch-a { color: var(--chan-a); }