:root {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --accent-primary: #10b981; /* Green for Heap */
    --accent-secondary: #38bdf8;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --border-color: rgba(255, 255, 255, 0.1);
    --node-normal: #334155;
    --node-active: #f59e0b;
    --node-swapped: #818cf8;
}

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

body {
    background: var(--bg-primary);
    color: var(--text-primary);
    font-family: 'Inter', sans-serif;
    overflow: hidden;
    height: 100vh;
}

.top-nav {
    height: 60px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 2rem;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
}

.nav-brand {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--accent-primary);
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: 1.5rem;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
}

.simulator-container {
    display: grid;
    grid-template-columns: 280px 1fr 350px;
    height: calc(100vh - 60px);
}

/* Sidebar Styles */
.sidebar {
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
}

.sidebar-header { padding: 1.5rem; }
.sidebar-header h2 { font-size: 0.8rem; color: var(--text-secondary); text-transform: uppercase; }

.operation-panel {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.input-group {
    display: flex;
    gap: 0.5rem;
}

.input-group input {
    flex: 1;
    background: #0f172a;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    padding: 0.5rem;
    font-size: 0.9rem;
}

.primary-btn {
    padding: 0.5rem 1rem;
    background: var(--accent-primary);
    border: none;
    border-radius: 6px;
    color: white;
    font-weight: 600;
    cursor: pointer;
}

.secondary-btn {
    padding: 0.6rem;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    font-size: 0.85rem;
    cursor: pointer;
}

.controls-panel {
    margin-top: auto;
    padding: 1.5rem;
    border-top: 1px solid var(--border-color);
}

.controls-panel h3 { font-size: 0.75rem; color: var(--text-secondary); margin-bottom: 1rem; }

.main-controls {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 1rem;
    margin-top: 1rem;
}

.icon-btn { background: none; border: none; color: var(--text-primary); font-size: 1.25rem; cursor: pointer; }
.play-btn { width: 45px; height: 45px; border-radius: 50%; background: var(--accent-primary); border: none; display: flex; justify-content: center; align-items: center; cursor: pointer; }

/* Visualizer Area */
.visualizer-area {
    display: flex;
    flex-direction: column;
    padding: 1.5rem;
    background: #0c1220;
}

.viz-header { display: flex; justify-content: space-between; margin-bottom: 1.5rem; }
.viz-legend { display: flex; gap: 1rem; }
.legend-item { font-size: 0.75rem; display: flex; align-items: center; gap: 0.4rem; color: var(--text-secondary); }
.dot { width: 8px; height: 8px; border-radius: 50%; }
.dot.normal { background: var(--node-normal); }
.dot.active { background: var(--node-active); }
.dot.swapped { background: var(--node-swapped); }

.canvas-container {
    flex: 1;
    background: rgba(255, 255, 255, 0.02);
    border-radius: 12px;
    border: 1px solid var(--border-color);
    margin-bottom: 1.5rem;
}

#heap-canvas { width: 100%; height: 100%; }

.array-viz-panel {
    background: var(--bg-secondary);
    border-radius: 12px;
    padding: 1rem;
    border: 1px solid var(--border-color);
}

.array-container {
    display: flex;
    gap: 0.25rem;
    overflow-x: auto;
    padding-bottom: 0.5rem;
}

.array-slot {
    min-width: 40px;
    height: 40px;
    display: flex;
    justify-content: center;
    align-items: center;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 0.8rem;
    font-weight: 600;
}

.array-slot.active { border-color: var(--node-active); background: rgba(245, 158, 11, 0.1); }
.array-slot.swapped { border-color: var(--node-swapped); background: rgba(129, 140, 248, 0.1); }

/* Explanation Side */
.explanation-side {
    background: var(--bg-secondary);
    border-left: 1px solid var(--border-color);
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    overflow-y: auto;
}

.code-block {
    background: #0f172a;
    padding: 1rem;
    border-radius: 8px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    line-height: 1.5;
    border: 1px solid var(--border-color);
}

.step-log { flex: 1; display: flex; flex-direction: column; }
.log-view {
    flex: 1;
    background: rgba(0, 0, 0, 0.2);
    border-radius: 8px;
    padding: 0.75rem;
    font-size: 0.85rem;
    overflow-y: auto;
}

.log-entry {
    padding: 0.5rem;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-secondary);
    animation: fadeIn 0.3s ease;
}

.log-entry.highlight { color: var(--accent-primary); font-weight: 600; }

@keyframes fadeIn { from { opacity: 0; transform: translateY(5px); } to { opacity: 1; transform: translateY(0); } }

input[type="range"] { width: 100%; accent-color: var(--accent-primary); }
.lang-select { background: #0f172a; color: white; border: 1px solid var(--border-color); font-size: 0.7rem; }