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

:root {
  --bg: #1a1a2e;
  --bg-panel: #16213e;
  --bg-input: #0f3460;
  --accent: #e94560;
  --accent2: #0f3460;
  --text: #eee;
  --text-dim: #999;
  --border: #333;
  --success: #4ecca3;
  --warn: #f0a500;
  --radius: 6px;
  --sidebar-width: 340px;
}

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

#app {
  display: flex;
  height: 100vh;
  width: 100vw;
}

/* Sidebar */
.sidebar {
  width: var(--sidebar-width);
  min-width: var(--sidebar-width);
  background: var(--bg-panel);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
  overflow-x: hidden;
  transition: width 0.3s, min-width 0.3s;
}

.sidebar.collapsed {
  width: 0;
  min-width: 0;
  overflow: hidden;
}

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: var(--bg-panel);
  z-index: 10;
}

.sidebar-header h1 {
  font-size: 16px;
  font-weight: 600;
  white-space: nowrap;
}

/* Panels */
.panel {
  border-bottom: 1px solid var(--border);
}

.panel-header {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  cursor: pointer;
  user-select: none;
  background: rgba(255,255,255,0.03);
}

.panel-header:hover {
  background: rgba(255,255,255,0.06);
}

.panel-header h2 {
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  flex: 1;
  white-space: nowrap;
}

.panel-arrow {
  font-size: 10px;
  transition: transform 0.2s;
  color: var(--text-dim);
}

.panel.collapsed .panel-arrow {
  transform: rotate(-90deg);
}

.panel.collapsed .panel-body {
  display: none;
}

.panel-body {
  padding: 8px 16px 12px;
}

/* Buttons */
.btn-icon {
  background: none;
  border: none;
  color: var(--text);
  cursor: pointer;
  font-size: 16px;
  padding: 4px 8px;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
}

.btn-icon:hover {
  background: rgba(255,255,255,0.1);
}

.btn-add {
  background: var(--accent);
  border: none;
  color: white;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  font-size: 16px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-left: auto;
  flex-shrink: 0;
  line-height: 1;
}

.btn-add:hover {
  opacity: 0.85;
}

.btn-primary {
  background: var(--accent);
  border: none;
  color: white;
  padding: 8px 16px;
  border-radius: var(--radius);
  cursor: pointer;
  font-size: 13px;
  font-weight: 600;
  width: 100%;
  margin-top: 8px;
}

.btn-primary:hover {
  opacity: 0.9;
}

.btn-secondary {
  background: var(--accent2);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 6px 12px;
  border-radius: var(--radius);
  cursor: pointer;
  font-size: 12px;
  width: 100%;
  margin-top: 6px;
}

.btn-secondary:hover {
  background: rgba(15, 52, 96, 0.8);
}

.btn-remove {
  background: none;
  border: none;
  color: var(--text-dim);
  cursor: pointer;
  font-size: 14px;
  padding: 2px 6px;
  border-radius: var(--radius);
  flex-shrink: 0;
}

.btn-remove:hover {
  color: var(--accent);
  background: rgba(233, 69, 96, 0.15);
}

/* Form elements */
input[type="text"],
input[type="number"],
select {
  background: var(--bg-input);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 6px 10px;
  border-radius: var(--radius);
  font-size: 13px;
  font-family: 'Consolas', 'Fira Code', monospace;
  width: 100%;
}

input[type="text"]:focus,
input[type="number"]:focus,
select:focus {
  outline: none;
  border-color: var(--accent);
}

.form-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 6px;
}

.form-row label {
  font-size: 12px;
  min-width: 50px;
  color: var(--text-dim);
}

.form-row input {
  flex: 1;
}

/* List items */
.list-item {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 6px;
  padding: 4px 8px;
  background: rgba(255,255,255,0.03);
  border-radius: var(--radius);
  border: 1px solid transparent;
}

.list-item:hover {
  border-color: var(--border);
}

.list-item input[type="text"],
.list-item input[type="number"] {
  padding: 4px 8px;
  font-size: 12px;
}

.list-item .var-name {
  font-family: 'Consolas', 'Fira Code', monospace;
  font-weight: 600;
  min-width: 30px;
}

.eq-row {
  margin-bottom: 8px;
}

.eq-row .eq-lhs {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-bottom: 4px;
}

.eq-row .eq-lhs select {
  width: auto;
  min-width: 60px;
}

.eq-row .eq-lhs .eq-deriv-select {
  width: auto;
  min-width: 50px;
  font-size: 11px;
}

.eq-row .eq-lhs span {
  color: var(--text-dim);
  font-size: 14px;
}

.eq-row input.eq-rhs {
  width: 100%;
  font-size: 13px;
}

/* IC items */
.ic-item {
  background: rgba(255,255,255,0.03);
  border-radius: var(--radius);
  padding: 8px;
  margin-bottom: 8px;
  border: 1px solid var(--border);
}

.ic-item .ic-header {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 6px;
}

.ic-item .ic-header input {
  flex: 1;
  font-weight: 600;
}

.ic-item .ic-color {
  width: 24px;
  height: 24px;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  padding: 0;
  background: none;
}

.ic-values {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
  gap: 4px;
}

.ic-val {
  display: flex;
  align-items: center;
  gap: 4px;
  font-size: 12px;
}

.ic-val label {
  font-family: 'Consolas', monospace;
  color: var(--text-dim);
  min-width: 20px;
}

.ic-val input {
  width: 60px;
  padding: 3px 6px;
  font-size: 12px;
}

/* Plot config items */
.plot-config-item {
  background: rgba(255,255,255,0.03);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 8px;
  margin-bottom: 8px;
}

.plot-config-item .pc-header {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 6px;
}

.plot-config-item .pc-header input {
  flex: 1;
  font-weight: 600;
  font-size: 12px;
}

.pc-row {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 4px;
  font-size: 12px;
}

.pc-row label {
  min-width: 40px;
  color: var(--text-dim);
}

.pc-row select {
  font-size: 12px;
  padding: 3px 6px;
}

.pc-traces {
  margin-top: 6px;
  padding-top: 6px;
  border-top: 1px solid var(--border);
}

.pc-traces-label {
  font-size: 11px;
  color: var(--text-dim);
  text-transform: uppercase;
  margin-bottom: 4px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.pc-trace-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  margin-bottom: 3px;
}

.pc-trace-item input[type="checkbox"] {
  accent-color: var(--accent);
}

.pc-options {
  margin-top: 6px;
  padding-top: 6px;
  border-top: 1px solid var(--border);
}

.pc-option-row {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  margin-bottom: 4px;
}

.pc-option-row label {
  color: var(--text-dim);
}

.pc-option-row input[type="checkbox"] {
  accent-color: var(--accent);
}

.pc-var-item {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 3px;
  font-size: 12px;
}

.pc-var-item select {
  flex: 1;
  font-size: 12px;
  padding: 3px 6px;
}

.pc-var-item input[type="range"] {
  width: 60px;
}

.pc-var-item .scale-label {
  font-size: 11px;
  color: var(--text-dim);
  min-width: 30px;
  text-align: right;
}

.pc-buttons {
  display: flex;
  gap: 6px;
  margin-top: 6px;
}

.pc-buttons button {
  flex: 1;
}

/* Main content */
#main-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

/* Animation controls */
#anim-controls {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  background: var(--bg-panel);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

#time-slider {
  flex: 1;
  accent-color: var(--accent);
}

#time-display {
  font-family: 'Consolas', monospace;
  font-size: 13px;
  min-width: 100px;
}

#speed-slider {
  width: 80px;
  accent-color: var(--accent);
}

#anim-controls label {
  font-size: 12px;
  color: var(--text-dim);
  display: flex;
  align-items: center;
  gap: 4px;
  white-space: nowrap;
}

/* Tabs */
#plot-tabs {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.tab-bar {
  display: flex;
  gap: 2px;
  padding: 4px 8px 0;
  background: var(--bg-panel);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.tab {
  background: rgba(255,255,255,0.05);
  border: 1px solid var(--border);
  border-bottom: none;
  color: var(--text-dim);
  padding: 6px 16px;
  border-radius: var(--radius) var(--radius) 0 0;
  cursor: pointer;
  font-size: 13px;
}

.tab.active {
  background: var(--bg);
  color: var(--text);
}

.tab .tab-close {
  margin-left: 8px;
  opacity: 0.5;
}

.tab .tab-close:hover {
  opacity: 1;
}

.tab-content {
  display: none;
  flex: 1;
  overflow: hidden;
}

.tab-content.active {
  display: flex;
}

/* Plot grid */
.plot-grid {
  flex: 1;
  display: flex;
  flex-wrap: wrap;
  align-content: flex-start;
  overflow-y: auto;
  padding: 8px;
  gap: 8px;
}

.plot-container {
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  position: relative;
  min-height: 300px;
  flex: 1 1 calc(50% - 8px);
  min-width: 400px;
  display: flex;
  flex-direction: column;
}

.plot-container.fullwidth {
  flex-basis: 100%;
}

.plot-toolbar {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 4px 8px;
  background: rgba(0,0,0,0.3);
  font-size: 12px;
  flex-shrink: 0;
}

.plot-toolbar .plot-title {
  flex: 1;
  font-weight: 600;
}

.plot-toolbar button {
  background: none;
  border: none;
  color: var(--text-dim);
  cursor: pointer;
  padding: 2px 6px;
  border-radius: 3px;
  font-size: 12px;
}

.plot-toolbar button:hover {
  background: rgba(255,255,255,0.1);
  color: var(--text);
}

.plot-area {
  flex: 1;
  min-height: 0;
}

.plot-area .js-plotly-plot,
.plot-area .plotly {
  width: 100% !important;
  height: 100% !important;
}

/* Empty state */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  width: 100%;
  color: var(--text-dim);
  font-size: 14px;
  text-align: center;
  padding: 40px;
}

.empty-state p {
  margin-bottom: 8px;
}

.empty-state .hint {
  font-size: 12px;
  opacity: 0.6;
}

/* Modal */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0,0,0,0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
}

.modal-overlay.hidden {
  display: none;
}

.modal {
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 20px;
  min-width: 400px;
  max-width: 500px;
  max-height: 80vh;
  overflow-y: auto;
}

.modal h3 {
  margin-bottom: 16px;
  font-size: 16px;
}

.modal-footer {
  display: flex;
  justify-content: flex-end;
  gap: 8px;
  margin-top: 16px;
}

.modal-footer button {
  width: auto;
  min-width: 80px;
}

/* Solve status */
#solve-status {
  font-size: 12px;
  margin-top: 6px;
  color: var(--text-dim);
}

#solve-status.error {
  color: var(--accent);
}

#solve-status.success {
  color: var(--success);
}

/* Analysis results */
#analysis-results {
  margin-top: 8px;
  font-size: 12px;
  font-family: 'Consolas', monospace;
  white-space: pre-wrap;
  max-height: 200px;
  overflow-y: auto;
  background: rgba(0,0,0,0.2);
  padding: 8px;
  border-radius: var(--radius);
}

/* Scrollbar */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: rgba(255,255,255,0.15);
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
  background: rgba(255,255,255,0.25);
}

/* Responsive */
@media (max-width: 900px) {
  .sidebar {
    --sidebar-width: 280px;
  }
  .plot-container {
    min-width: 300px;
  }
}

/* Phase plot controls */
.phase-axis-row {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 4px;
}

.phase-axis-row label {
  min-width: 50px;
  font-size: 12px;
  color: var(--text-dim);
}

.phase-axis-row select {
  flex: 1;
  font-size: 12px;
}

.phase-fixed-vars {
  margin-top: 6px;
  padding-top: 6px;
  border-top: 1px solid var(--border);
}

.phase-fixed-var {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 3px;
  font-size: 12px;
}

.phase-fixed-var label {
  min-width: 30px;
  font-family: 'Consolas', monospace;
  color: var(--text-dim);
}

.phase-fixed-var input {
  width: 80px;
  font-size: 12px;
  padding: 3px 6px;
}

.phase-grid-row {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 4px;
  font-size: 12px;
}

.phase-grid-row label {
  color: var(--text-dim);
  min-width: 80px;
}

.phase-grid-row input {
  width: 60px;
  font-size: 12px;
  padding: 3px 6px;
}

/* Toggle sidebar button when collapsed */
#expand-sidebar {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 100;
  background: var(--bg-panel);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 6px 10px;
  border-radius: var(--radius);
  cursor: pointer;
  font-size: 14px;
  display: none;
}

.sidebar.collapsed ~ #main-content #expand-sidebar {
  display: block;
}