:root {
  --bg: #f8f9fa;
  --panel: #e9ecef;
  --input: #dee2e6;
  --hover: #ced4da;
  --accent: #2563eb;
  --text: #1f2937;
  --dim: #6b7280;
  --border: #adb5bd;
  --warn: #dc2626;
}

* { box-sizing: border-box; }

html, body { height: 100%; margin: 0; }

body {
  display: grid;
  grid-template-columns: 240px 1fr 220px;
  gap: 8px;
  padding: 8px;
  font: 13px/1.4 "Segoe UI", system-ui, sans-serif;
  color: var(--text);
  background: var(--bg);
}

.panel { overflow-y: auto; display: flex; flex-direction: column; gap: 12px; }

section {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px;
}

h2 {
  margin: 0 0 8px;
  font-size: 12px;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: .03em;
}

label { display: block; margin: 4px 0; cursor: pointer; }

.btn {
  display: inline-block;
  width: 100%;
  text-align: center;
  background: var(--input);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 7px 10px;
  margin: 3px 0;
  color: var(--text);
  cursor: pointer;
  font-size: 13px;
}
.btn:hover { background: var(--hover); }
.btn:active { background: var(--accent); color: #fff; }
.btn.primary { background: var(--accent); color: #fff; border-color: var(--accent); }
.btn.primary:hover { filter: brightness(1.08); }
.btn.active { background: var(--accent); color: #fff; }
.file-btn { cursor: pointer; }

input[type="number"] {
  width: 100%;
  padding: 6px 8px;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: #fff;
  color: var(--text);
}
input.error { border-color: var(--warn); background: #fff5f5; }

.row { display: flex; gap: 6px; align-items: center; }
.row .btn { margin: 3px 0; width: auto; flex: 1; }
#layer-prev, #layer-next, #int-prev, #int-next { flex: 0 0 42px; }
.status { flex: 1; min-width: 0; text-align: center; white-space: nowrap; font-variant-numeric: tabular-nums; }

.coeff { display: flex; align-items: center; justify-content: space-between; gap: 8px; margin: 5px 0; }
.coeff label { margin: 0; flex: 1; }
.coeff input[type="number"] { width: 90px; }

.dim { color: var(--dim); }
.small { font-size: 11px; }
.info { margin: 0; white-space: pre-wrap; font: 12px/1.45 "Segoe UI", sans-serif; color: var(--text); min-height: 6em; }

.plot-wrap {
  position: relative;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
}
.plot-title {
  position: absolute; top: 6px; left: 0; right: 0;
  text-align: center; font-weight: 600; font-size: 13px; pointer-events: none;
}
#plot { display: block; width: 100%; height: 100%; cursor: crosshair; }