:root {
    --bg-color: #f0f2f5;
    --text-color: #333;
    --primary-color: #3b82f6;
    --secondary-color: #6b7280;
    --accent-color: #8b5cf6;
    
    /* Bar Colors */
    --bar-default: #60a5fa;
    --bar-compare: #f59e0b; /* Yellow/Orange */
    --bar-swap: #ef4444;    /* Red */
    --bar-sorted: #10b981;  /* Green */
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    padding: 20px;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    background: white;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

header {
    text-align: center;
    margin-bottom: 30px;
}

h1 {
    color: var(--text-color);
    margin-bottom: 10px;
}

.subtitle {
    color: var(--secondary-color);
    font-size: 1.1em;
}

.visualization-container {
    height: 300px;
    display: flex;
    align-items: flex-end;
    justify-content: center;
    gap: 4px;
    padding: 20px;
    background-color: #f8fafc;
    border-radius: 8px;
    border: 1px solid #e2e8f0;
    margin-bottom: 20px;
}

.bar {
    width: 30px;
    background-color: var(--bar-default);
    border-radius: 4px 4px 0 0;
    transition: height 0.2s ease, background-color 0.2s ease;
    display: flex;
    align-items: flex-end;
    justify-content: center;
    color: white;
    font-size: 12px;
    padding-bottom: 5px;
}

.status-panel {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding: 15px;
    background-color: #eff6ff;
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
}

#status-text {
    font-weight: 500;
    font-size: 1.1em;
}

.legend {
    display: flex;
    gap: 15px;
}

.legend-item {
    display: flex;
    align-items: center;
    font-size: 0.9em;
    color: var(--secondary-color);
}

.color-box {
    width: 12px;
    height: 12px;
    display: inline-block;
    margin-right: 5px;
    border-radius: 2px;
}

.color-box.default { background-color: var(--bar-default); }
.color-box.compare { background-color: var(--bar-compare); }
.color-box.swap { background-color: var(--bar-swap); }
.color-box.sorted { background-color: var(--bar-sorted); }

.controls {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 20px;
    margin-bottom: 40px;
}

.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    font-size: 1em;
    cursor: pointer;
    transition: transform 0.1s, opacity 0.2s;
}

.btn:active {
    transform: scale(0.98);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn.primary {
    background-color: var(--primary-color);
    color: white;
}

.btn.secondary {
    background-color: var(--secondary-color);
    color: white;
}

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

.educational-content {
    border-top: 1px solid #e2e8f0;
    padding-top: 30px;
}

.educational-content h2 {
    margin-bottom: 15px;
    font-size: 1.5em;
}

.concept-explanation {
    background-color: #f9fafb;
    padding: 20px;
    border-radius: 8px;
}

.key-points {
    margin-top: 15px;
}

.key-points ul {
    list-style-position: inside;
    margin-top: 10px;
}

.key-points li {
    margin-bottom: 8px;
}