:root {
  --bg: #0f1115;
  --panel: #161a22;
  --panel-2: #1e242f;
  --border: #2a313d;
  --text: #e4e7ec;
  --muted: #8a93a3;
  --accent: #f08a24;
  --accent-2: #4fa3ff;
  --danger: #d94a4a;
  --grid: #1f2530;
  --grid-major: #2a3140;
  --cell: #4a5365;
  --cell-sel: #f08a24;
  --cell-busbar: #4fa3ff;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font: 14px/1.4 -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
}

body {
  display: flex;
  flex-direction: column;
  height: 100vh;
  overflow: hidden;   /* never let the page itself scroll — flex children handle their own overflow */
}

/* ---- topbar ---- */
.topbar {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 10px 16px;
  background: var(--panel);
  border-bottom: 1px solid var(--border);
}

.topbar h1 {
  margin: 0;
  font-size: 16px;
  font-weight: 600;
  letter-spacing: 0.02em;
}

.topbar .status {
  color: var(--muted);
  font-size: 13px;
}

.topbar .actions {
  margin-left: auto;
  display: flex;
  gap: 8px;
  align-items: center;
}

.topbar-nav {
  display: flex;
  gap: 4px;
  padding: 0 12px;
  border-left: 1px solid var(--border);
}

.topbar-nav a {
  color: var(--muted);
  text-decoration: none;
  padding: 4px 10px;
  font-size: 13px;
  border-bottom: 2px solid transparent;
}

.topbar-nav a:hover { color: var(--text); }
.topbar-nav a.active {
  color: var(--text);
  border-bottom-color: var(--accent);
}

.project-bar {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 0 12px;
  border-left: 1px solid var(--border);
  border-right: 1px solid var(--border);
}

.project-bar select,
.project-bar input[type=text] {
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 4px 8px;
  font: inherit;
  font-size: 13px;
  width: auto;
  min-width: 120px;
}

.project-bar select { min-width: 140px; }

.save-status {
  color: var(--muted);
  font-size: 11px;
  font-family: "SF Mono", Consolas, monospace;
  margin-left: 4px;
  min-width: 50px;
}

.topbar-status {
  color: var(--muted);
  font-size: 12px;
  padding-left: 8px;
  margin-left: 4px;
  border-left: 1px solid var(--border);
  white-space: nowrap;
}
.save-status.dirty  { color: var(--accent); }
.save-status.saving { color: var(--accent-2); }
.save-status.saved  { color: #3ecf8e; }
.save-status.error  { color: var(--danger); }

button.danger {
  background: var(--panel);
  color: var(--danger);
  border-color: var(--danger);
}
button.danger:hover {
  background: var(--danger);
  color: #fff;
}

/* ---- modal ---- */
.modal {
  position: fixed; inset: 0;
  background: rgba(0,0,0,0.6);
  display: flex; align-items: center; justify-content: center;
  z-index: 1000;
}
.modal.hidden { display: none; }
.modal-content {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 8px;
  max-width: 560px;
  width: 90vw;
  max-height: 80vh;
  display: flex; flex-direction: column;
  overflow: hidden;
}
.modal-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 10px 14px;
  background: var(--panel-2);
  border-bottom: 1px solid var(--border);
}
.modal-header h3 { margin: 0; font-size: 14px; }
.modal-close {
  background: transparent; border: 0;
  color: var(--muted); font-size: 20px; line-height: 1;
  cursor: pointer; padding: 0 4px;
}
.modal-close:hover { color: var(--text); }
.modal-body {
  padding: 12px 14px;
  overflow-y: auto;
}

.history-list {
  list-style: none; margin: 0; padding: 0;
}
.history-item {
  display: flex; align-items: center; gap: 10px;
  padding: 6px 8px;
  border: 1px solid var(--border);
  border-radius: 4px;
  margin-bottom: 4px;
  background: var(--bg);
}
.history-item .time {
  font-family: "SF Mono", Consolas, monospace;
  font-size: 12px;
  color: var(--muted);
  min-width: 140px;
}
.history-item .note { flex: 1; color: var(--text); font-size: 12px; }
.history-item button { padding: 2px 8px; font-size: 11px; }

.topbar .sep {
  width: 1px;
  height: 22px;
  background: var(--border);
  margin: 0 6px;
}

/* ---- main grid ---- */
main {
  display: flex;
  flex: 1;
  min-height: 0;
}

.left {
  width: 380px;
  flex-shrink: 0;
  background: var(--panel);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  padding: 12px;
}

.right {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  background: var(--bg);
}

.viewport-wrap {
  flex: 1 1 auto;
  min-height: 0;
  position: relative;
  overflow: hidden;
}

.step-preview-wrap {
  flex: 0 0 auto;
  border-top: 1px solid var(--border);
  background: var(--panel);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  height: 280px;
}

.step-preview-wrap.collapsed {
  height: auto;
}
.step-preview-wrap.collapsed .step-preview {
  display: none;
}
.step-preview-wrap.collapsed .step-preview-collapse {
  transform: rotate(180deg);
}

.step-preview-collapse {
  background: transparent;
  color: var(--muted);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 0 6px;
  font-size: 10px;
  line-height: 1;
  cursor: pointer;
  margin-right: 4px;
}
.step-preview-collapse:hover { color: var(--text); }

.step-preview-header {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 6px 12px;
  border-bottom: 1px solid var(--border);
  background: var(--panel-2);
  font-size: 12px;
}

.step-preview-header .hint { margin: 0; font-size: 11px; }

.step-preview {
  flex: 1;
  overflow: auto;
  background: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
}

.step-preview svg {
  display: block;
  max-width: 100%;
  max-height: 100%;
  width: auto;
  height: auto;
}

.step-preview-empty,
.step-preview-err {
  color: var(--muted);
  font-size: 12px;
  padding: 16px;
  text-align: center;
}
.step-preview-err { color: var(--danger); }

.preset-row {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-bottom: 10px;
  flex-wrap: wrap;
}
.preset-row select { flex: 1; min-width: 140px; }
.preset-row button { padding: 4px 8px; font-size: 11px; }
.preset-row .hint { margin: 0; font-size: 11px; flex-basis: 100%; }

#viewport {
  display: block;
  width: 100%;
  height: 100%;
  cursor: crosshair;
}

.viewport-overlay {
  position: absolute;
  bottom: 8px;
  left: 12px;
  display: flex;
  gap: 16px;
  pointer-events: none;
  color: var(--muted);
  font-size: 12px;
  font-family: "SF Mono", Consolas, monospace;
  background: rgba(15, 17, 21, 0.6);
  padding: 4px 8px;
  border-radius: 4px;
}

/* ---- panels ---- */
.panel {
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 12px;
  margin-bottom: 12px;
}

.panel h2 {
  margin: 0 0 10px;
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
}

.hint {
  color: var(--muted);
  font-size: 12px;
  margin: 0 0 8px;
}

.hint code {
  background: rgba(255,255,255,0.05);
  padding: 1px 4px;
  border-radius: 3px;
  font-size: 11px;
}

/* ---- tabs ---- */
.tabs {
  display: flex;
  gap: 2px;
  margin-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

.tab {
  flex: 1;
  background: transparent;
  color: var(--muted);
  border: 0;
  border-bottom: 2px solid transparent;
  padding: 6px 8px;
  cursor: pointer;
  font-size: 12px;
}

.tab.active {
  color: var(--text);
  border-bottom-color: var(--accent);
}

.tab-body { display: block; }
.tab-body.hidden { display: none; }

/* ---- forms ---- */
.grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

label {
  display: flex;
  flex-direction: column;
  gap: 4px;
  color: var(--muted);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

label.checkbox {
  flex-direction: row;
  align-items: center;
  gap: 6px;
  text-transform: none;
  letter-spacing: 0;
  font-size: 12px;
  color: var(--text);
}

input[type=number], input[type=text], select, textarea {
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 6px 8px;
  font: inherit;
  width: 100%;
}

textarea {
  resize: vertical;
  font-family: "SF Mono", Consolas, monospace;
  font-size: 12px;
}

input:focus, select:focus, textarea:focus {
  outline: none;
  border-color: var(--accent-2);
}

button {
  background: var(--panel);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 6px 12px;
  cursor: pointer;
  font: inherit;
}

button:hover { background: var(--panel-2); }
button:active { transform: translateY(1px); }
button:disabled { opacity: 0.4; cursor: not-allowed; }

button.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #1a1a1a;
  font-weight: 600;
}

button.primary:hover { background: #ff9933; }

.tab-body button {
  margin-top: 8px;
}

/* ---- busbars ---- */
.busbar-toolbar {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 8px;
}

.sel-info {
  color: var(--muted);
  font-size: 12px;
  margin-left: auto;
}

.busbar-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.busbar-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 4px;
  margin-bottom: 6px;
}

.busbar-item.active {
  border-color: var(--accent);
}

.busbar-color {
  width: 16px;
  height: 16px;
  border-radius: 4px;
  cursor: pointer;
  flex-shrink: 0;
  border: 1px solid rgba(255,255,255,0.2);
}

.busbar-name {
  flex: 1;
  background: transparent;
  border: 0;
  color: var(--text);
  padding: 2px 4px;
  font: inherit;
}

.busbar-name:focus { background: var(--panel); border-radius: 3px; }

.busbar-count {
  color: var(--muted);
  font-size: 11px;
  font-family: "SF Mono", Consolas, monospace;
}

.busbar-shape {
  background: var(--panel);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 3px;
  font-size: 11px;
  padding: 1px 4px;
  width: auto;
}

.busbar-actions { display: flex; gap: 4px; }

.busbar-actions button {
  padding: 2px 6px;
  font-size: 11px;
}

.busbar-actions .del { color: var(--danger); border-color: var(--danger); }

@media (max-width: 1000px) {
  .left { width: 320px; }
}