:root {
  /* Light theme (default / day) */
  --bg: #eaeef6;
  --bg-2: #f1f4fa;
  --panel: #ffffff;
  --panel-2: #f3f6fc;
  --panel-3: #e9eef7;
  --text: #16203a;
  --muted: #61708f;
  --border: #dbe2ee;
  --border-strong: #c4cee0;
  --accent: #3b6fe0;
  --accent-2: #2b57c0;
  --accent-soft: rgba(59, 111, 224, 0.12);
  --danger: #e0455a;
  --danger-soft: rgba(224, 69, 90, 0.12);
  --ok: #12a97b;
  --warn: #d4870f;

  --radius-sm: 6px;
  --radius: 10px;
  --radius-lg: 14px;
  --radius-xl: 18px;

  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 24px;
  --space-6: 32px;

  --shadow-sm: 0 1px 2px rgba(20, 30, 55, 0.06), 0 1px 3px rgba(20, 30, 55, 0.08);
  --shadow-md: 0 4px 12px rgba(20, 30, 55, 0.10);
  --shadow-lg: 0 18px 48px rgba(20, 30, 55, 0.22);
  --ring: 0 0 0 3px var(--accent-soft);
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme='dark'] {
  --bg: #0d1220;
  --bg-2: #141b2c;
  --panel: #1a2338;
  --panel-2: #212c46;
  --panel-3: #27334f;
  --text: #e7ecf7;
  --muted: #97a4c0;
  --border: #2b3652;
  --border-strong: #3b4869;
  --accent: #5b93ff;
  --accent-2: #3f79ee;
  --accent-soft: rgba(91, 147, 255, 0.18);
  --danger: #ff6274;
  --danger-soft: rgba(255, 98, 116, 0.18);
  --ok: #3ad9a4;
  --warn: #ffc15c;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 6px 18px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 22px 60px rgba(0, 0, 0, 0.55);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  height: 100%;
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  overflow: hidden;
}

.hidden { display: none !important; }
.muted { color: var(--muted); }
.small { font-size: 0.8rem; }
.error { color: var(--danger); min-height: 1.2em; font-size: 0.85rem; }
code { background: var(--panel-2); padding: 1px 6px; border-radius: var(--radius-sm); }

/* Focus accessibility */
:focus-visible { outline: none; box-shadow: var(--ring); border-radius: var(--radius-sm); }

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  background: var(--panel);
  color: var(--text);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  padding: 8px 14px;
  min-height: 34px;
  cursor: pointer;
  font-size: 0.85rem;
  font-weight: 500;
  line-height: 1;
  box-shadow: var(--shadow-sm);
  transition: background 0.16s var(--ease), border-color 0.16s var(--ease),
    transform 0.08s var(--ease), box-shadow 0.16s var(--ease), color 0.16s var(--ease);
}
.btn:hover { border-color: var(--accent); color: var(--accent); transform: translateY(-1px); box-shadow: var(--shadow-md); }
.btn:active { transform: translateY(0); box-shadow: var(--shadow-sm); }
.btn.active {
  border-color: var(--accent); color: var(--accent);
  background: var(--accent-soft);
  box-shadow: inset 0 0 0 1.5px var(--accent);
}
.btn.active[aria-pressed="true"]:hover { transform: none; }
.btn.primary {
  background: linear-gradient(180deg, var(--accent), var(--accent-2));
  border-color: var(--accent-2); color: #fff;
}
.btn.primary:hover { color: #fff; filter: brightness(1.05); }
.btn.danger { border-color: var(--danger); color: var(--danger); background: var(--panel); }
.btn.danger:hover { background: var(--danger); color: #fff; border-color: var(--danger); }
.btn.small { padding: 5px 10px; min-height: 28px; font-size: 0.76rem; }
.btn.icon { padding: 7px 10px; }
.btn.full { width: 100%; margin-top: var(--space-3); }

/* Login */
.overlay {
  position: fixed; inset: 0;
  display: flex; align-items: center; justify-content: center;
  background: radial-gradient(1200px 600px at 50% -10%, var(--bg-2), var(--bg));
  z-index: 100;
}
.login-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  width: 360px;
  box-shadow: var(--shadow-lg);
  display: flex; flex-direction: column; gap: var(--space-3);
  animation: pop 0.28s var(--ease);
}
.login-card h1 { margin: 0; font-size: 1.5rem; letter-spacing: -0.01em; }
.login-card label { display: flex; flex-direction: column; gap: var(--space-1); font-size: 0.85rem; }
.login-card input {
  background: var(--panel-2); border: 1px solid var(--border-strong);
  border-radius: var(--radius); padding: 11px; color: var(--text); font-size: 0.95rem;
  transition: border-color 0.16s var(--ease), box-shadow 0.16s var(--ease);
}
.login-card input:focus { border-color: var(--accent); box-shadow: var(--ring); outline: none; }
.login-card .btn { margin-top: var(--space-2); }

/* Topbar */
.topbar {
  display: flex; align-items: center; gap: var(--space-4);
  padding: var(--space-3) var(--space-4);
  background: var(--panel); border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow-sm); z-index: 5;
}
.brand { display: flex; align-items: center; gap: var(--space-2); font-weight: 700; font-size: 1.08rem; letter-spacing: -0.01em; }
.brand-logo { height: 28px; width: auto; display: block; object-fit: contain; }
.topbar-project { flex: 1; font-size: 0.9rem; }
.topbar-actions { display: flex; align-items: center; gap: var(--space-2); }
.topbar-actions::before {
  content: ''; width: 1px; height: 24px; background: var(--border);
  margin-right: var(--space-1);
}
.badge {
  background: var(--accent-soft); color: var(--accent); border: 1px solid transparent;
  border-radius: 20px; padding: 4px 12px; font-size: 0.72rem; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.03em;
}

/* Layout */
.layout {
  display: grid; grid-template-columns: 312px 1fr 292px;
  height: calc(100vh - 61px);
  transition: grid-template-columns 0.28s var(--ease);
}
.layout.left-collapsed { grid-template-columns: 0 1fr 292px; }
.layout.right-collapsed { grid-template-columns: 312px 1fr 0; }
.layout.left-collapsed.right-collapsed { grid-template-columns: 0 1fr 0; }
.sidebar {
  background: var(--bg-2); border-right: 1px solid var(--border);
  overflow-y: auto; overflow-x: hidden; padding: var(--space-3);
  scrollbar-width: thin;
}
.sidebar.right { border-right: none; border-left: 1px solid var(--border); }

.panel {
  background: var(--panel); border: 1px solid var(--border);
  border-radius: var(--radius-lg); margin-bottom: var(--space-3);
  box-shadow: var(--shadow-sm); overflow: hidden;
}
.panel-head {
  display: flex; align-items: center; justify-content: space-between; gap: var(--space-2);
  padding: var(--space-3);
}
.panel-body {
  padding: 0 var(--space-3) var(--space-3);
  overflow: hidden;
  transition: max-height 0.26s var(--ease), opacity 0.2s var(--ease), padding 0.26s var(--ease);
}
.panel.collapsed .panel-body { max-height: 0 !important; opacity: 0; padding-top: 0; padding-bottom: 0; }
.panel.collapsed .chevron { transform: rotate(-90deg); }
.collapse-toggle {
  display: flex; align-items: center; gap: var(--space-2); flex: 1;
  background: none; border: none; cursor: pointer; padding: 0; color: var(--text); text-align: left;
}
.collapse-toggle h3 { margin: 0; font-size: 0.92rem; font-weight: 650; }
.chevron { font-size: 0.7rem; color: var(--muted); transition: transform 0.24s var(--ease); }

.list { display: flex; flex-direction: column; gap: var(--space-2); }
.list-item {
  background: var(--panel-2); border: 1px solid var(--border); border-radius: var(--radius);
  padding: var(--space-3); font-size: 0.82rem; cursor: pointer;
  display: flex; flex-direction: column; gap: var(--space-1);
  transition: border-color 0.16s var(--ease), box-shadow 0.16s var(--ease),
    transform 0.1s var(--ease), background 0.16s var(--ease);
}
.list-item:hover { border-color: var(--accent); box-shadow: var(--shadow-md); transform: translateY(-1px); }
.list-item.active { border-color: var(--accent); box-shadow: inset 0 0 0 1.5px var(--accent); background: var(--accent-soft); }
.list-item .row { display: flex; justify-content: space-between; align-items: center; gap: var(--space-2); }
.list-item .title { font-weight: 600; }
.list-item .sub { color: var(--muted); font-size: 0.75rem; }
.list .muted.small {
  border: 1px dashed var(--border-strong); border-radius: var(--radius);
  padding: var(--space-4); text-align: center; margin: 0;
}
.chip {
  display: inline-block; padding: 2px 9px; border-radius: 20px; font-size: 0.68rem;
  font-weight: 600; color: #fff; white-space: nowrap;
}
.item-actions { display: flex; gap: var(--space-1); flex-wrap: wrap; margin-top: var(--space-1); }
.item-actions .btn { padding: 3px 9px; min-height: 24px; font-size: 0.72rem; box-shadow: none; }

/* Scene */
.scene-wrap { position: relative; display: flex; flex-direction: column; background: var(--bg); min-width: 0; overflow: hidden; }
.scene-toolbar {
  display: flex; align-items: center; gap: var(--space-2); padding: var(--space-2) var(--space-3);
  background: var(--panel); border-bottom: 1px solid var(--border); flex-wrap: wrap;
}
.scene-toolbar .spacer { flex: 1; }
.inline { display: inline-flex; align-items: center; gap: var(--space-2); font-size: 0.82rem; color: var(--muted); }
.scene-toolbar select {
  background: var(--panel); color: var(--text); border: 1px solid var(--border-strong);
  border-radius: var(--radius); padding: 7px 10px; min-height: 34px; font-size: 0.83rem;
}
.scene-toolbar select:focus { border-color: var(--accent); box-shadow: var(--ring); outline: none; }

/* Fine-tune "Move" pad: nudge the selected item along the viewer's axes. */
.nudge-pad {
  display: inline-flex; align-items: center; gap: var(--space-2);
  padding: 2px var(--space-2); border: 1px solid var(--border);
  border-radius: var(--radius); background: var(--panel-2);
}
.nudge-pad .nudge-title { font-size: 0.72rem; color: var(--muted); text-transform: uppercase; letter-spacing: 0.04em; }
.nudge-pad .nudge-grid {
  display: grid; grid-template-columns: repeat(3, 22px); grid-template-rows: repeat(2, 22px);
  gap: 2px; align-items: center; justify-items: center;
}
/* Cross layout: ▲ top-center, ◀ ▼ ▶ on the bottom row. */
.nudge-pad .nudge-grid [data-dir="forward"] { grid-column: 2; grid-row: 1; }
.nudge-pad .nudge-grid [data-dir="left"]    { grid-column: 1; grid-row: 2; }
.nudge-pad .nudge-grid [data-dir="back"]    { grid-column: 2; grid-row: 2; }
.nudge-pad .nudge-grid [data-dir="right"]   { grid-column: 3; grid-row: 2; }
.nudge-pad .nudge-vert { display: inline-flex; flex-direction: column; gap: 2px; }
.nudge-pad button.nudge {
  padding: 0; min-height: 0; line-height: 1;
  display: inline-flex; align-items: center; justify-content: center;
}
.nudge-pad .nudge-grid button.nudge { width: 22px; height: 22px; font-size: 0.7rem; }
.nudge-pad .nudge-vert button.nudge { padding: 3px 6px; font-size: 0.68rem; }
.nudge-pad.disabled { opacity: 0.45; }
.nudge-pad button.nudge:disabled { cursor: default; }

#canvas-container { flex: 1; position: relative; min-width: 0; min-height: 0; }
#canvas-container canvas { display: block; width: 100%; height: 100%; }

/* Sidebar collapse handles */
.sidebar-handle {
  position: absolute; top: 50%; transform: translateY(-50%); z-index: 6;
  width: 22px; height: 52px; border: 1px solid var(--border-strong);
  background: var(--panel); color: var(--muted); cursor: pointer;
  display: flex; align-items: center; justify-content: center; font-size: 1rem;
  box-shadow: var(--shadow-sm); transition: color 0.16s var(--ease), background 0.16s var(--ease);
}
.sidebar-handle:hover { color: var(--accent); background: var(--panel-2); }
.sidebar-handle.left { left: 0; border-left: none; border-radius: 0 var(--radius) var(--radius) 0; }
.sidebar-handle.right { right: 0; border-right: none; border-radius: var(--radius) 0 0 var(--radius); }

/* Controls / shortcuts reference (shown in a modal via the toolbar button) */
.shortcuts { display: grid; grid-template-columns: 1fr 1fr; gap: var(--space-4); }
.shortcuts-group { display: flex; flex-direction: column; gap: var(--space-2); }
.shortcuts-group h3 {
  margin: 0; font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.06em;
  color: var(--muted); border-bottom: 1px solid var(--border); padding-bottom: var(--space-1);
}
.shortcuts-row {
  display: flex; align-items: baseline; gap: var(--space-3);
  font-size: 0.85rem; line-height: 1.35;
}
.shortcuts-row .keys { flex: 0 0 auto; display: inline-flex; gap: 4px; align-items: center; flex-wrap: wrap; }
.shortcuts-row .desc { color: var(--text); }
kbd {
  display: inline-block; min-width: 1.1em; text-align: center;
  padding: 2px 7px; font-size: 0.72rem; font-family: inherit; line-height: 1.4;
  color: var(--text); background: var(--panel-2);
  border: 1px solid var(--border-strong); border-bottom-width: 2px;
  border-radius: 5px; box-shadow: var(--shadow-sm); white-space: nowrap;
}
@media (max-width: 560px) { .shortcuts { grid-template-columns: 1fr; } }

/* Stats */
.stats { display: flex; flex-direction: column; gap: var(--space-2); }
.stat-row { display: flex; justify-content: space-between; font-size: 0.85rem; }
.stat-row .k { color: var(--muted); }
.bar { height: 9px; background: var(--panel-3); border-radius: 6px; overflow: hidden; }
.bar > span { display: block; height: 100%; background: var(--accent); border-radius: 6px; transition: width 0.35s var(--ease); }
.bar.warn > span { background: var(--warn); }
.bar.over > span { background: var(--danger); }

/* Balance indicator */
.stat-section { margin-top: var(--space-2); font-size: 0.85rem; font-weight: 600; }
.stat-section .k { color: var(--text); }
.balance-item { display: flex; flex-direction: column; gap: 2px; margin-top: 2px; }
/* Segmented weight-distribution histogram: cells laid neg→pos across the floor,
   each cell's fill height scaled to its share of the load. Balanced = green,
   near-threshold = amber, unbalanced = red. */
.balance-hist {
  position: relative; display: flex; align-items: flex-end; gap: 0;
  height: 22px; background: var(--panel-3); border-radius: 6px;
  overflow: hidden; padding: 1px;
}
/* Center reference line */
.balance-hist::before {
  content: ''; position: absolute; top: -1px; bottom: -1px; left: 50%;
  width: 1px; background: var(--border-strong); transform: translateX(-0.5px); z-index: 2;
}
.balance-hist > .cell {
  position: relative; flex: 1 1 0; height: 100%;
  display: flex; align-items: flex-end;
}
.balance-hist > .cell > .cell-fill {
  display: block; width: 100%; min-height: 1px; background: var(--ok);
  border-radius: 1px; transition: height 0.35s var(--ease), background 0.35s var(--ease);
}
.balance-hist.warn > .cell > .cell-fill { background: var(--warn); }
.balance-hist.over > .cell > .cell-fill { background: var(--danger); }
/* Center-of-gravity marker */
.balance-hist > .cog-marker {
  position: absolute; top: -1px; bottom: -1px; width: 2px; z-index: 3;
  background: var(--text); transform: translateX(-1px);
  transition: left 0.35s var(--ease);
}
.balance-labels {
  display: flex; justify-content: space-between; gap: var(--space-2);
  font-size: 0.72rem; color: var(--muted);
}
.balance-labels > span:nth-child(2) { text-align: center; }

/* Modal */
.modal-backdrop {
  position: fixed; inset: 0; background: rgba(10, 15, 30, 0.5);
  backdrop-filter: blur(2px);
  display: flex; align-items: center; justify-content: center; z-index: 200;
  animation: fade 0.18s var(--ease);
}
.modal {
  background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-lg);
  width: min(640px, 92vw); max-height: 88vh; overflow-y: auto;
  box-shadow: var(--shadow-lg); animation: pop 0.24s var(--ease);
}
.modal-header {
  display: flex; align-items: center; justify-content: space-between; gap: var(--space-3);
  padding: var(--space-4) var(--space-5);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; background: var(--panel); z-index: 1;
}
.modal-header h2 { margin: 0; font-size: 1.12rem; }
.modal-close {
  border: none; background: var(--panel-2); color: var(--muted);
  width: 32px; height: 32px; border-radius: 50%; cursor: pointer; font-size: 1.1rem;
  display: flex; align-items: center; justify-content: center; line-height: 1;
  transition: background 0.16s var(--ease), color 0.16s var(--ease), transform 0.1s var(--ease);
}
.modal-close:hover { background: var(--danger-soft); color: var(--danger); transform: rotate(90deg); }
.modal-content { padding: var(--space-5); }
.modal h2 { margin-top: 0; }
.modal .form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: var(--space-3); }
.modal label { display: flex; flex-direction: column; gap: var(--space-1); font-size: 0.82rem; }
.modal input, .modal select, .modal textarea {
  background: var(--panel-2); border: 1px solid var(--border-strong); border-radius: var(--radius);
  padding: 10px; color: var(--text); font-size: 0.9rem; width: 100%;
  transition: border-color 0.16s var(--ease), box-shadow 0.16s var(--ease);
}
.modal input:focus, .modal select:focus, .modal textarea:focus {
  border-color: var(--accent); box-shadow: var(--ring); outline: none;
}
.modal .full-col { grid-column: 1 / -1; }
.modal-actions {
  display: flex; justify-content: flex-end; gap: var(--space-2); margin-top: var(--space-5);
  padding-top: var(--space-4); border-top: 1px solid var(--border);
}

/* Comparison table */
.compare-table { width: 100%; border-collapse: collapse; font-size: 0.85rem; }
.compare-table th, .compare-table td { border: 1px solid var(--border); padding: var(--space-2) var(--space-3); text-align: left; }
.compare-table th { background: var(--panel-2); position: sticky; top: 0; }
.compare-table td.best { background: color-mix(in srgb, var(--ok) 18%, transparent); font-weight: 600; }

/* Toast */
#toast-host { position: fixed; bottom: var(--space-4); right: var(--space-4); display: flex; flex-direction: column; gap: var(--space-2); z-index: 300; }
.toast {
  background: var(--panel); border: 1px solid var(--border); border-left: 4px solid var(--accent);
  padding: var(--space-3) var(--space-4); border-radius: var(--radius); box-shadow: var(--shadow-md);
  font-size: 0.85rem; max-width: 320px; cursor: pointer;
  animation: slidein 0.22s var(--ease); transition: opacity 0.3s var(--ease), transform 0.3s var(--ease);
}
.toast:hover { transform: translateX(-3px); }
.toast.error { border-left-color: var(--danger); }
.toast.ok { border-left-color: var(--ok); }

/* Animations */
@keyframes fade { from { opacity: 0; } to { opacity: 1; } }
@keyframes pop { from { opacity: 0; transform: translateY(8px) scale(0.98); } to { opacity: 1; transform: none; } }
@keyframes slidein { from { opacity: 0; transform: translateX(20px); } to { opacity: 1; transform: none; } }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    transition-duration: 0.001ms !important;
  }
}

/* Report preview modal (Load Plan) — hosts a branded print document in an
   isolated iframe so print styling is faithful and does not inherit the app
   theme. Widen the modal when it contains a report preview. */
.modal:has(.report-modal) { width: min(920px, 94vw); }
.report-modal { display: flex; flex-direction: column; gap: var(--space-4); }
.report-preview {
  width: 100%; height: min(70vh, 780px); border: 1px solid var(--border);
  border-radius: var(--radius); background: #fff; box-shadow: var(--shadow-sm);
}

/* Printouts (Manifest & Load Plan) open in a dedicated window and carry their
   own self-contained stylesheet, so no app-level @media print rules are needed. */