:root,
[data-theme="light"] {
  --bg-app: #f1f5f9;
  --bg-panel: #ffffff;
  --bg-card: #f1f5f9;
  --bg-card-hover: #e2e8f0;
  --bg-input: #f8fafc;
  --border-subtle: #e2e8f0;
  --border-default: #cbd5e1;
  --border-focus: #0284c7;
  --text-main: #0f172a;
  --text-muted: #475569;
  --text-dim: #64748b;

  --accent-primary: #0284c7;
  --accent-primary-hover: #0ea5e9;
  --accent-purple: #9333ea;
  --accent-amber: #d97706;
  --accent-success: #059669;
  --accent-danger: #dc2626;

  --edge-convex: #0284c7;
  --edge-concave: #db2777;
  --edge-selected: #eab308;

  --viewport-bg: radial-gradient(circle at 50% 35%, #ffffff 0%, #dbeafe 55%, #cbd5e1 100%);
  --hud-bg: rgba(255, 255, 255, 0.88);
  --summary-box-bg: #f8fafc;
  --empty-state-bg: #f8fafc;
  --modal-backdrop: rgba(15, 23, 42, 0.45);
}

[data-theme="dark"] {
  --bg-app: #0b0f17;
  --bg-panel: #111827;
  --bg-card: #1e293b;
  --bg-card-hover: #263449;
  --bg-input: #0f172a;
  --border-subtle: #1f2937;
  --border-default: #334155;
  --border-focus: #38bdf8;
  --text-main: #f1f5f9;
  --text-muted: #94a3b8;
  --text-dim: #64748b;

  --accent-primary: #0ea5e9;
  --accent-primary-hover: #38bdf8;
  --accent-purple: #a855f7;
  --accent-amber: #f59e0b;
  --accent-success: #10b981;
  --accent-danger: #ef4444;

  --edge-convex: #38bdf8;
  --edge-concave: #f472b6;
  --edge-selected: #facc15;

  --viewport-bg: radial-gradient(circle at 50% 35%, #1e293b 0%, #090d16 100%);
  --hud-bg: rgba(15, 23, 42, 0.82);
  --summary-box-bg: rgba(15, 23, 42, 0.7);
  --empty-state-bg: rgba(15, 23, 42, 0.45);
  --modal-backdrop: rgba(2, 6, 23, 0.72);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html,
body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: var(--bg-app);
  color: var(--text-main);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Inter, sans-serif;
  font-size: 13px;
  line-height: 1.4;
  user-select: none;
  transition: background-color 0.2s ease, color 0.2s ease;
}

/* Topbar */
.topbar {
  height: 56px;
  background: var(--bg-panel);
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 16px;
  gap: 12px;
  z-index: 20;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
}

.brand-icon {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  background: linear-gradient(135deg, rgba(14, 165, 233, 0.18), rgba(168, 85, 247, 0.18));
  border: 1px solid rgba(14, 165, 233, 0.35);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-main);
}

.brand-title {
  font-size: 15px;
  font-weight: 700;
  letter-spacing: -0.01em;
  display: flex;
  align-items: center;
  gap: 6px;
}

.badge-stl {
  font-size: 10px;
  font-weight: 700;
  padding: 1px 6px;
  border-radius: 4px;
  background: rgba(14, 165, 233, 0.14);
  color: var(--edge-convex);
  border: 1px solid rgba(14, 165, 233, 0.35);
}

.brand-subtitle {
  font-size: 11px;
  color: var(--text-muted);
}

.topbar-center {
  display: flex;
  align-items: center;
  gap: 12px;
}

.file-actions,
.history-actions,
.topbar-right {
  display: flex;
  align-items: center;
  gap: 8px;
}

.divider-v {
  width: 1px;
  height: 24px;
  background: var(--border-default);
}

/* Buttons & Inputs */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  height: 34px;
  padding: 0 12px;
  border-radius: 6px;
  font-size: 12.5px;
  font-weight: 600;
  border: 1px solid var(--border-subtle);
  cursor: pointer;
  transition: all 0.15s ease;
  color: var(--text-main);
  background: var(--bg-card);
  white-space: nowrap;
}

.btn:hover:not(:disabled) {
  background: var(--bg-card-hover);
}

.btn:disabled {
  opacity: 0.42;
  cursor: not-allowed;
}

.btn-primary {
  background: linear-gradient(180deg, #0ea5e9, #0284c7);
  border-color: #0284c7;
  color: #fff;
}

.btn-primary:hover:not(:disabled) {
  background: linear-gradient(180deg, #38bdf8, #0ea5e9);
}

.btn-success {
  background: linear-gradient(180deg, #10b981, #059669);
  border-color: #059669;
  color: #fff;
}

.btn-success:hover:not(:disabled) {
  background: linear-gradient(180deg, #34d399, #10b981);
}

.btn-ghost {
  background: transparent;
  border-color: var(--border-default);
  color: var(--text-muted);
}

.btn-ghost:hover:not(:disabled) {
  background: var(--bg-card);
  color: var(--text-main);
}

.btn-sm {
  height: 28px;
  padding: 0 10px;
  font-size: 11.5px;
}

.full-width {
  width: 100%;
}

.select-input {
  height: 34px;
  padding: 0 10px;
  border-radius: 6px;
  background: var(--bg-input);
  border: 1px solid var(--border-default);
  color: var(--text-main);
  font-size: 12.5px;
  outline: none;
  cursor: pointer;
}

.select-input:focus {
  border-color: var(--border-focus);
}

/* Engine Status Badge */
.engine-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--bg-input);
  border: 1px solid var(--border-default);
  font-size: 11px;
  color: var(--text-muted);
}

.status-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--accent-amber);
}

.status-dot.ready {
  background: var(--accent-success);
  box-shadow: 0 0 6px var(--accent-success);
}

/* Workspace Layout */
.workspace {
  display: grid;
  grid-template-columns: 300px 1fr 320px;
  height: calc(100vh - 56px);
  width: 100%;
}

.sidebar {
  background: var(--bg-panel);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
  z-index: 10;
}

.sidebar-left {
  border-right: 1px solid var(--border-subtle);
}

.sidebar-right {
  border-left: 1px solid var(--border-subtle);
}

.panel-section {
  padding: 14px 16px;
  border-bottom: 1px solid var(--border-subtle);
}

.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
}

.section-header h2 {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

.badge-subtle {
  font-size: 11px;
  padding: 2px 7px;
  border-radius: 999px;
  background: var(--bg-card);
  color: var(--text-muted);
}

.control-group {
  margin-bottom: 14px;
}

.control-group:last-child {
  margin-bottom: 0;
}

.control-label {
  display: block;
  font-size: 12px;
  font-weight: 600;
  color: var(--text-main);
  margin-bottom: 6px;
}

.control-hint {
  font-size: 11px;
  color: var(--text-dim);
  margin-top: 5px;
}

.label-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 6px;
}

.label-row .control-label {
  margin-bottom: 0;
}

.value-pill {
  font-size: 11.5px;
  font-weight: 700;
  padding: 1px 7px;
  border-radius: 4px;
  background: rgba(14, 165, 233, 0.14);
  color: var(--edge-convex);
}

/* Segmented Control */
.segmented-control {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  background: var(--bg-input);
  padding: 3px;
  border-radius: 7px;
  border: 1px solid var(--border-default);
  gap: 2px;
}

.seg-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 11px;
  font-weight: 600;
  padding: 6px 4px;
  border-radius: 5px;
  cursor: pointer;
  transition: all 0.12s ease;
}

.seg-btn:hover {
  color: var(--text-main);
}

.seg-btn.active {
  background: var(--bg-panel);
  color: var(--edge-convex);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.12);
}

[data-theme="dark"] .seg-btn.active {
  background: var(--bg-card);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.35);
}

/* Range Sliders */
.range-slider {
  width: 100%;
  accent-color: var(--accent-primary);
  cursor: pointer;
  height: 6px;
}

.range-sublabels {
  display: flex;
  justify-content: space-between;
  font-size: 10.5px;
  color: var(--text-dim);
  margin-top: 3px;
}

/* Filter Chips */
.filter-pills {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.filter-chip {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 7px 9px;
  border-radius: 6px;
  background: var(--bg-input);
  border: 1px solid var(--border-default);
  font-size: 11.5px;
  cursor: pointer;
}

.filter-chip input {
  accent-color: var(--accent-primary);
}

.dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  display: inline-block;
}

.convex-dot {
  background: var(--edge-convex);
  box-shadow: 0 0 5px var(--edge-convex);
}

.concave-dot {
  background: var(--edge-concave);
  box-shadow: 0 0 5px var(--edge-concave);
}

/* Selection Summary Box */
.selection-summary-box {
  background: var(--summary-box-bg);
  border: 1px solid var(--border-default);
  border-radius: 8px;
  padding: 10px;
}

.summary-stat {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
  margin-bottom: 6px;
}

.stat-label {
  color: var(--text-muted);
}

.stat-value {
  font-weight: 700;
  color: var(--accent-amber);
}

[data-theme="dark"] .stat-value {
  color: var(--edge-selected);
}

.summary-actions {
  display: flex;
  gap: 6px;
  margin-top: 8px;
}

.summary-actions .btn {
  flex: 1;
}

/* Edge List */
.edge-list-container,
.history-list {
  max-height: 210px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.empty-state {
  padding: 14px 10px;
  text-align: center;
  color: var(--text-dim);
  font-size: 11.5px;
  background: var(--empty-state-bg);
  border: 1px dashed var(--border-default);
  border-radius: 6px;
}

kbd {
  padding: 1px 5px;
  border-radius: 4px;
  background: var(--bg-card);
  border: 1px solid var(--border-default);
  font-size: 10.5px;
  color: var(--text-main);
}

.edge-item,
.history-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 6px 9px;
  border-radius: 6px;
  background: var(--bg-input);
  border: 1px solid var(--border-subtle);
  font-size: 11.5px;
}

.edge-item-left {
  display: flex;
  align-items: center;
  gap: 7px;
}

.edge-type-tag {
  font-size: 10px;
  font-weight: 700;
  padding: 1px 5px;
  border-radius: 4px;
  text-transform: uppercase;
}

.edge-type-tag.convex {
  background: rgba(14, 165, 233, 0.15);
  color: var(--edge-convex);
}

.edge-type-tag.concave {
  background: rgba(236, 72, 153, 0.15);
  color: var(--edge-concave);
}

.edge-remove-btn {
  background: none;
  border: none;
  color: var(--text-dim);
  cursor: pointer;
  font-size: 14px;
  line-height: 1;
  padding: 2px 4px;
}

.edge-remove-btn:hover {
  color: var(--accent-danger);
}

/* Model Info */
.info-grid {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.info-item {
  display: flex;
  justify-content: space-between;
  font-size: 11.5px;
}

.info-label {
  color: var(--text-muted);
}

.info-val {
  font-weight: 600;
  color: var(--text-main);
  font-variant-numeric: tabular-nums;
}

/* Operation Cards */
.op-type-cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.op-card {
  display: flex;
  align-items: center;
  gap: 9px;
  padding: 10px;
  border-radius: 8px;
  background: var(--bg-input);
  border: 1.5px solid var(--border-default);
  color: var(--text-main);
  cursor: pointer;
  text-align: left;
  transition: all 0.15s ease;
}

.op-card:hover {
  border-color: var(--text-muted);
}

.op-card.active {
  background: rgba(14, 165, 233, 0.12);
  border-color: var(--edge-convex);
  box-shadow: 0 0 0 1px rgba(14, 165, 233, 0.2);
}

.op-card-text {
  display: flex;
  flex-direction: column;
}

.op-card-text strong {
  font-size: 12.5px;
}

.op-card-text span {
  font-size: 10.5px;
  color: var(--text-muted);
}

/* Number Input & Quick Presets */
.number-input-wrap {
  display: flex;
  align-items: center;
  background: var(--bg-input);
  border: 1px solid var(--border-default);
  border-radius: 5px;
  padding-right: 6px;
}

.number-input {
  width: 58px;
  height: 26px;
  background: transparent;
  border: none;
  color: var(--text-main);
  font-size: 12.5px;
  font-weight: 700;
  text-align: right;
  padding: 0 4px;
  outline: none;
}

.unit-tag {
  font-size: 11px;
  color: var(--text-dim);
}

.quick-presets {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 5px;
  margin-top: 7px;
}

.preset-btn {
  padding: 4px 0;
  font-size: 11px;
  font-weight: 600;
  border-radius: 5px;
  background: var(--bg-input);
  border: 1px solid var(--border-default);
  color: var(--text-muted);
  cursor: pointer;
}

.preset-btn:hover,
.preset-btn.active {
  background: rgba(14, 165, 233, 0.15);
  border-color: var(--edge-convex);
  color: var(--edge-convex);
}

.checkbox-row {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  color: var(--text-main);
  cursor: pointer;
}

.sub-control {
  margin-top: 10px;
  padding: 10px;
  border-radius: 7px;
  background: var(--summary-box-bg);
  border: 1px solid var(--border-subtle);
}

.hidden {
  display: none !important;
}

/* Apply CTA */
.apply-box {
  margin-top: 16px;
}

.btn-apply {
  width: 100%;
  height: 42px;
  font-size: 13.5px;
  font-weight: 700;
  background: linear-gradient(135deg, #f59e0b, #ea580c);
  border-color: #ea580c;
  color: #fff;
  box-shadow: 0 4px 14px rgba(245, 158, 11, 0.25);
}

.btn-apply:hover:not(:disabled) {
  background: linear-gradient(135deg, #fbbf24, #f97316);
  transform: translateY(-1px);
}

.apply-hint {
  font-size: 11px;
  color: var(--text-dim);
  margin-top: 8px;
  line-height: 1.45;
}

/* Viewport & Overlays */
.viewport-wrapper {
  position: relative;
  width: 100%;
  height: 100%;
  background: var(--viewport-bg);
  overflow: hidden;
  transition: background 0.25s ease;
}

.canvas-container {
  width: 100%;
  height: 100%;
}

.viewport-hud {
  position: absolute;
  z-index: 5;
  pointer-events: auto;
}

.hud-top-left {
  top: 14px;
  left: 14px;
}

.hud-top-right {
  top: 14px;
  right: 14px;
  display: flex;
  gap: 6px;
}

.hud-bottom-center {
  bottom: 14px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--hud-bg);
  backdrop-filter: blur(8px);
  border: 1px solid var(--border-default);
  padding: 6px 14px;
  border-radius: 999px;
  font-size: 11.5px;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 8px;
  white-space: nowrap;
  pointer-events: none;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
}

.hud-bottom-center strong {
  color: var(--text-main);
}

.legend-card {
  background: var(--hud-bg);
  backdrop-filter: blur(8px);
  border: 1px solid var(--border-default);
  border-radius: 8px;
  padding: 8px 12px;
  display: flex;
  flex-direction: column;
  gap: 5px;
  font-size: 11px;
  color: var(--text-muted);
  pointer-events: none;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 8px;
}

.legend-line {
  width: 18px;
  height: 3px;
  border-radius: 2px;
}

.legend-line.convex {
  background: var(--edge-convex);
}

.legend-line.concave {
  background: var(--edge-concave);
}

.legend-line.selected {
  background: #f59e0b;
}

.hud-btn {
  background: var(--hud-bg);
  backdrop-filter: blur(8px);
  border: 1px solid var(--border-default);
  color: var(--text-muted);
  padding: 6px 11px;
  border-radius: 6px;
  font-size: 11.5px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s ease;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
}

.hud-btn:hover {
  color: var(--text-main);
  border-color: var(--text-muted);
}

.hud-btn.active {
  color: var(--edge-convex);
  border-color: var(--edge-convex);
  background: rgba(14, 165, 233, 0.14);
}

/* Hover Tooltip */
.edge-tooltip {
  position: absolute;
  pointer-events: none;
  z-index: 15;
  background: var(--bg-panel);
  border: 1px solid var(--border-default);
  border-radius: 6px;
  padding: 6px 10px;
  font-size: 11.5px;
  color: var(--text-main);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.18);
  transform: translate(12px, -50%);
  white-space: nowrap;
}

/* Drop Overlay */
.drop-overlay {
  position: absolute;
  inset: 12px;
  background: rgba(14, 165, 233, 0.12);
  backdrop-filter: blur(4px);
  border: 2px dashed var(--edge-convex);
  border-radius: 12px;
  z-index: 30;
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
}

.drop-card {
  background: var(--bg-panel);
  padding: 28px 36px;
  border-radius: 12px;
  border: 1px solid var(--border-default);
  text-align: center;
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.25);
}

.drop-card h3 {
  font-size: 16px;
  margin: 10px 0 4px;
}

.drop-card p {
  font-size: 12px;
  color: var(--text-muted);
}

/* Modal (Libraries & Credits) */
.modal-backdrop {
  position: fixed;
  inset: 0;
  background: var(--modal-backdrop);
  backdrop-filter: blur(4px);
  z-index: 90;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.modal-card {
  background: var(--bg-panel);
  border: 1px solid var(--border-default);
  border-radius: 12px;
  width: 100%;
  max-width: 540px;
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.35);
  overflow: hidden;
  animation: slideIn 0.18s ease-out;
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  border-bottom: 1px solid var(--border-subtle);
}

.modal-header h3 {
  font-size: 15px;
  font-weight: 700;
}

.modal-close-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 18px;
  cursor: pointer;
  padding: 4px 8px;
  border-radius: 6px;
}

.modal-close-btn:hover {
  background: var(--bg-card);
  color: var(--text-main);
}

.modal-body {
  padding: 18px 20px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-height: 70vh;
  overflow-y: auto;
}

.modal-intro {
  font-size: 12.5px;
  color: var(--text-muted);
  line-height: 1.5;
}

.lib-card {
  padding: 12px 14px;
  border-radius: 8px;
  background: var(--bg-input);
  border: 1px solid var(--border-subtle);
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.lib-card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.lib-name {
  font-size: 13.5px;
  font-weight: 700;
  color: var(--text-main);
  text-decoration: none;
}

a.lib-name:hover {
  color: var(--edge-convex);
  text-decoration: underline;
}

.lib-badges {
  display: flex;
  gap: 6px;
}

.lib-badge {
  font-size: 10.5px;
  font-weight: 600;
  padding: 2px 7px;
  border-radius: 999px;
  background: var(--bg-card);
  color: var(--text-muted);
  border: 1px solid var(--border-default);
}

.lib-badge.license {
  background: rgba(16, 185, 129, 0.14);
  color: var(--accent-success);
  border-color: rgba(16, 185, 129, 0.3);
}

.lib-desc {
  font-size: 12px;
  color: var(--text-muted);
  line-height: 1.45;
}

.modal-footer {
  padding: 12px 20px;
  border-top: 1px solid var(--border-subtle);
  display: flex;
  justify-content: flex-end;
  background: var(--bg-input);
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 100;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.toast {
  background: var(--bg-panel);
  border: 1px solid var(--border-default);
  border-left: 4px solid var(--accent-primary);
  color: var(--text-main);
  padding: 10px 14px;
  border-radius: 7px;
  font-size: 12.5px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.2);
  animation: slideIn 0.2s ease-out;
}

.toast.success {
  border-left-color: var(--accent-success);
}

.toast.warn {
  border-left-color: var(--accent-amber);
}

.toast.error {
  border-left-color: var(--accent-danger);
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}