/* ==========================================================================
   AlgoVision 2.0 - Unified DSA Analytics & Optimization Platform
   Handcrafted Light-First Design System • Engineered by Saikat Koner
   ========================================================================== */

:root {
  /* Light Theme (Default & Primary Eye-Catching Palette) */
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-card: #ffffff;
  --bg-glass: #f1f5f9;
  --border-color: #e2e8f0;
  --border-focus: #0284c7;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;

  --accent-blue: #0284c7;
  --accent-indigo: #4f46e5;
  --accent-cyan: #0891b2;
  --accent-emerald: #059669;
  --accent-amber: #d97706;
  --accent-rose: #e11d48;
  --accent-purple: #7c3aed;

  --node-bg: #ffffff;
  --node-border: #cbd5e1;
  --node-active: #0284c7;
  --node-visited: #059669;
  --node-cycle: #e11d48;

  --font-sans: 'Plus Jakarta Sans', 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 10px 25px -5px rgba(15, 23, 42, 0.08), 0 1px 3px 0 rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 20px 35px -10px rgba(15, 23, 42, 0.12), 0 1px 3px 0 rgba(0, 0, 0, 0.05);
  --glow-blue: 0 0 18px rgba(2, 132, 199, 0.25);
  --glow-emerald: 0 0 18px rgba(5, 150, 105, 0.25);
  --glow-rose: 0 0 18px rgba(225, 29, 72, 0.25);
}

[data-theme="dark"] {
  --bg-primary: #0a0f1d;
  --bg-secondary: #111827;
  --bg-card: #111827;
  --bg-glass: rgba(31, 41, 55, 0.7);
  --border-color: rgba(75, 85, 99, 0.4);
  --border-focus: #38bdf8;
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  --accent-blue: #38bdf8;
  --accent-indigo: #818cf8;
  --accent-cyan: #22d3ee;
  --accent-emerald: #34d399;
  --accent-amber: #fbbf24;
  --accent-rose: #fb7185;
  --accent-purple: #c084fc;

  --node-bg: #1f2937;
  --node-border: #4b5563;
  --node-active: #38bdf8;
  --node-visited: #34d399;
  --node-cycle: #fb7185;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  line-height: 1.55;
  overflow-x: hidden;
  background-image: radial-gradient(at 0% 0%, rgba(2, 132, 199, 0.04) 0px, transparent 50%),
                    radial-gradient(at 100% 100%, rgba(79, 70, 229, 0.04) 0px, transparent 50%);
}

/* Header & Navigation */
.app-header {
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-color);
  padding: 0.85rem 1.75rem;
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  box-shadow: var(--shadow-sm);
}

[data-theme="dark"] .app-header {
  background: rgba(17, 24, 39, 0.85);
}

.brand-section {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.brand-logo {
  width: 42px;
  height: 42px;
  background: linear-gradient(135deg, #0284c7, #4f46e5);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 1.25rem;
  color: #fff;
  box-shadow: 0 4px 14px rgba(2, 132, 199, 0.3);
}

.brand-info h1 {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.author-chip {
  font-size: 0.72rem;
  font-weight: 700;
  color: #0369a1;
  background: #e0f2fe;
  border: 1px solid #bae6fd;
  padding: 3px 8px;
  border-radius: 9999px;
  letter-spacing: 0;
}

.version-tag {
  font-size: 0.7rem;
  background: #ecfdf5;
  color: #047857;
  padding: 3px 8px;
  border-radius: 9999px;
  border: 1px solid #a7f3d0;
  font-weight: 700;
  font-family: var(--font-mono);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.scenario-select {
  background: var(--bg-secondary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  padding: 0.5rem 0.9rem;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-family: inherit;
  font-weight: 600;
  cursor: pointer;
  outline: none;
  box-shadow: var(--shadow-sm);
  transition: all 0.2s;
}

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

.btn-icon {
  background: var(--bg-secondary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  width: 38px;
  height: 38px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: all 0.2s;
  font-size: 1rem;
}

.btn-icon:hover {
  border-color: var(--accent-blue);
  color: var(--accent-blue);
  transform: scale(1.05);
}

/* Layout Core */
.app-container {
  display: flex;
  flex: 1;
  height: calc(100vh - 68px);
}

/* Sidebar Tabs */
.app-sidebar {
  width: 280px;
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  padding: 1.25rem 0.75rem;
  gap: 0.45rem;
  overflow-y: auto;
}

.nav-tab-btn {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 0.95rem;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  background: transparent;
  color: var(--text-secondary);
  font-size: 0.88rem;
  font-weight: 600;
  text-align: left;
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

.nav-tab-btn:hover {
  background: var(--bg-glass);
  color: var(--text-primary);
  transform: translateX(2px);
}

.nav-tab-btn.active {
  background: linear-gradient(135deg, rgba(2, 132, 199, 0.12), rgba(79, 70, 229, 0.08));
  color: var(--accent-blue);
  border-color: rgba(2, 132, 199, 0.3);
  font-weight: 700;
  box-shadow: 0 2px 8px rgba(2, 132, 199, 0.08);
}

.nav-tab-btn .tab-badge {
  margin-left: auto;
  font-size: 0.68rem;
  font-family: var(--font-mono);
  font-weight: 700;
  background: var(--bg-glass);
  color: var(--text-muted);
  padding: 2px 6px;
  border-radius: 6px;
  border: 1px solid var(--border-color);
}

.nav-tab-btn.active .tab-badge {
  background: #e0f2fe;
  color: #0284c7;
  border-color: #bae6fd;
}

/* Main Content Stage */
.main-stage {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow-y: auto;
  background: var(--bg-primary);
  padding: 1.5rem;
  gap: 1.25rem;
}

/* Control Bar */
.control-panel {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.85rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  box-shadow: var(--shadow-sm);
}

.controls-group {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.btn-primary {
  background: linear-gradient(135deg, #0284c7, #2563eb);
  color: #fff;
  border: none;
  padding: 0.55rem 1.15rem;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.25);
  transition: all 0.2s;
}

.btn-primary:hover {
  filter: brightness(1.08);
  transform: translateY(-1px);
  box-shadow: 0 6px 16px rgba(37, 99, 235, 0.35);
}

.btn-secondary {
  background: var(--bg-secondary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  padding: 0.55rem 0.95rem;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  box-shadow: var(--shadow-sm);
  transition: all 0.2s;
}

.btn-secondary:hover {
  border-color: var(--accent-blue);
  color: var(--accent-blue);
  background: #f0f9ff;
}

.speed-slider-wrap {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.speed-slider-wrap input[type="range"] {
  accent-color: var(--accent-blue);
  width: 100px;
}

/* Visualization Canvas Stage */
.stage-grid {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 1.25rem;
  flex: 1;
}

@media (max-width: 1024px) {
  .stage-grid {
    grid-template-columns: 1fr;
  }
}

.canvas-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  position: relative;
  min-height: 480px;
  box-shadow: var(--shadow-md);
}

.card-header {
  padding: 0.85rem 1.35rem;
  background: var(--bg-glass);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.card-title {
  font-size: 1rem;
  font-weight: 800;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.canvas-viewport {
  flex: 1;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.25rem;
  overflow: auto;
  background: #ffffff;
}

[data-theme="dark"] .canvas-viewport {
  background: #0f172a;
}

/* Telemetry & Inspector Panel */
.inspector-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  box-shadow: var(--shadow-md);
}

.metric-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

.metric-tile {
  background: var(--bg-glass);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 0.75rem 0.85rem;
}

.metric-label {
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.metric-value {
  font-size: 1.25rem;
  font-weight: 800;
  font-family: var(--font-mono);
  color: var(--accent-blue);
  margin-top: 0.25rem;
}

.code-dossier {
  background: #0f172a;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 0.85rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: #7dd3fc;
  overflow-x: auto;
  max-height: 200px;
}

.step-log-box {
  flex: 1;
  background: var(--bg-glass);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-secondary);
  overflow-y: auto;
  max-height: 220px;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.log-entry {
  padding: 4px 8px;
  border-radius: 4px;
  border-left: 3px solid var(--accent-blue);
  background: rgba(2, 132, 199, 0.06);
  color: var(--text-primary);
}

.log-entry.highlight {
  border-left-color: var(--accent-emerald);
  background: rgba(5, 150, 105, 0.08);
  color: #065f46;
  font-weight: 700;
}

.log-entry.alert {
  border-left-color: var(--accent-rose);
  background: rgba(225, 29, 72, 0.08);
  color: #9f1239;
  font-weight: 700;
}

/* Visualizer Custom Renderers */
/* 1. Circular Queue */
.circular-queue-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.5rem;
  width: 100%;
}

.queue-slots-row {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  justify-content: center;
}

.queue-slot {
  width: 58px;
  height: 58px;
  background: var(--node-bg);
  border: 2px solid var(--node-border);
  border-radius: var(--radius-sm);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  position: relative;
  box-shadow: var(--shadow-sm);
  transition: all 0.3s;
}

.queue-slot.occupied {
  border-color: var(--accent-blue);
  background: #f0f9ff;
  color: var(--accent-blue);
  font-weight: 800;
}

.queue-slot.head-ptr {
  border-color: var(--accent-emerald);
  box-shadow: var(--glow-emerald);
}

.queue-slot.head-ptr::before {
  content: 'HEAD';
  position: absolute;
  top: -18px;
  font-size: 0.65rem;
  color: var(--accent-emerald);
  font-weight: 800;
  font-family: var(--font-mono);
}

.queue-slot.tail-ptr {
  border-color: var(--accent-amber);
}

.queue-slot.tail-ptr::after {
  content: 'TAIL';
  position: absolute;
  bottom: -18px;
  font-size: 0.65rem;
  color: var(--accent-amber);
  font-weight: 800;
  font-family: var(--font-mono);
}

/* 2. Sorting Array Bars */
.sort-bars-container {
  display: flex;
  align-items: flex-end;
  gap: 6px;
  height: 280px;
  width: 100%;
  padding: 12px;
  background: #f8fafc;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
}

[data-theme="dark"] .sort-bars-container {
  background: rgba(0, 0, 0, 0.25);
}

.sort-bar {
  flex: 1;
  background: linear-gradient(180deg, #0284c7, #1d4ed8);
  border-radius: 6px 6px 0 0;
  transition: height 0.2s ease, background-color 0.2s;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  font-size: 0.7rem;
  font-family: var(--font-mono);
  font-weight: 700;
  color: #ffffff;
  padding-bottom: 4px;
}

.sort-bar.pivot1 {
  background: linear-gradient(180deg, #f59e0b, #d97706);
  box-shadow: 0 0 12px rgba(217, 119, 6, 0.5);
}

.sort-bar.pivot2 {
  background: linear-gradient(180deg, #8b5cf6, #6d28d9);
  box-shadow: 0 0 12px rgba(109, 40, 217, 0.5);
}

.sort-bar.comparing {
  background: linear-gradient(180deg, #f43f5e, #be123c);
}

.sort-bar.sorted {
  background: linear-gradient(180deg, #10b981, #047857);
}

/* 3. SVG Tree & Graph */
svg.visualizer-svg {
  width: 100%;
  height: 100%;
  min-height: 400px;
}

.tree-node-circle {
  fill: #ffffff;
  stroke: #94a3b8;
  stroke-width: 2.5;
  transition: all 0.3s;
  cursor: pointer;
  filter: drop-shadow(0 2px 4px rgba(0,0,0,0.06));
}

[data-theme="dark"] .tree-node-circle {
  fill: #1e293b;
  stroke: #475569;
}

.tree-node-circle.active {
  stroke: #0284c7;
  fill: #e0f2fe;
  filter: drop-shadow(0 0 10px rgba(2, 132, 199, 0.5));
}

.tree-node-circle.rotating {
  stroke: #d97706;
  fill: #fef3c7;
}

.tree-node-text {
  fill: #0f172a;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  text-anchor: middle;
  dominant-baseline: central;
  pointer-events: none;
}

[data-theme="dark"] .tree-node-text {
  fill: #f8fafc;
}

.tree-balance-text {
  fill: #0284c7;
  font-size: 10px;
  font-weight: 700;
  text-anchor: middle;
  dominant-baseline: central;
}

.graph-edge-line {
  stroke: #cbd5e1;
  stroke-width: 2;
  transition: all 0.3s;
}

[data-theme="dark"] .graph-edge-line {
  stroke: #334155;
}

.graph-edge-line.active {
  stroke: #0284c7;
  stroke-width: 4;
}

.graph-edge-line.mst {
  stroke: #059669;
  stroke-width: 4;
  filter: drop-shadow(0 0 6px rgba(5, 150, 105, 0.5));
}

.graph-edge-line.cycle {
  stroke: #e11d48;
  stroke-width: 4;
  stroke-dasharray: 6 3;
  animation: dashCycle 1s linear infinite;
}

@keyframes dashCycle {
  to {
    stroke-dashoffset: -18;
  }
}

/* 4. DP Matrix Table */
.dp-table-container {
  overflow: auto;
  max-height: 320px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  background: #ffffff;
}

.dp-matrix {
  border-collapse: collapse;
  width: 100%;
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

.dp-matrix th, .dp-matrix td {
  border: 1px solid var(--border-color);
  padding: 8px 12px;
  text-align: center;
}

.dp-matrix th {
  background: #f8fafc;
  color: var(--text-secondary);
  font-weight: 700;
}

.dp-matrix td.active-cell {
  background: #e0f2fe;
  color: #0369a1;
  font-weight: 800;
  box-shadow: inset 0 0 6px rgba(2, 132, 199, 0.3);
}

.dp-matrix td.selected-cell {
  background: #dcfce7;
  color: #15803d;
  font-weight: 800;
}

/* Custom Scrollbars */
::-webkit-scrollbar { width: 8px; height: 8px; }
::-webkit-scrollbar-track { background: #f1f5f9; }
::-webkit-scrollbar-thumb { background: #cbd5e1; border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: #94a3b8; }