:root {
    /* Red Culture Theme - Inherited from style.css */
    --app-bg: #fdfbf7;
    --sidebar-bg: rgba(255, 248, 240, 0.8);
    --glass-border: rgba(214, 59, 29, 0.2);
    --text-primary: #8b0000;
    --text-secondary: #a05a5a;
    --accent-red: #d63b1d;
    --accent-gold: #ffb400;
    --accent-hover: #b32b12;
    --danger-red: #ff3b30;
    --success-green: #27c93f;

    --shadow-sm: 0 2px 8px rgba(139, 0, 0, 0.08);
    --shadow-md: 0 8px 24px rgba(139, 0, 0, 0.12);
    --shadow-lg: 0 20px 40px rgba(139, 0, 0, 0.15);

    --font-family: "Noto Serif SC", "Outfit", serif;
    --font-title: "Ma Shan Zheng", cursive;
}

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

body {
    font-family: var(--font-family);
    background-color: var(--app-bg);
    color: var(--text-primary);
    height: 100vh;
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    background-image: url('https://images.unsplash.com/photo-1533038590840-1cde6e668a91?q=80&w=2574&auto=format&fit=crop');
    background-size: cover;
    background-position: center;
}

.app-container {
    width: 90vw;
    height: 85vh;
    max-width: 1400px;
    background: rgba(255, 252, 245, 0.85);
    backdrop-filter: blur(20px) saturate(120%);
    -webkit-backdrop-filter: blur(20px) saturate(120%);
    border-radius: 24px;
    border: 1px solid var(--glass-border);
    box-shadow: var(--shadow-lg);
    display: flex;
    overflow: hidden;
}

/* Sidebar */
.sidebar {
    width: 340px;
    background: var(--sidebar-bg);
    border-right: 1px solid var(--glass-border);
    display: flex;
    flex-direction: column;
    padding: 1.5rem;
    gap: 1.5rem;
    flex-shrink: 0;
    overflow-y: auto;
}

.sidebar-header {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.window-controls {
    display: flex;
    gap: 8px;
}

.dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
}

.dot.red {
    background: #ff5f56;
    border: 1px solid #e0443e;
}

.dot.yellow {
    background: #ffbd2e;
    border: 1px solid #dea123;
}

.dot.green {
    background: #27c93f;
    border: 1px solid #1aab29;
}

h1 {
    font-family: var(--font-title);
    font-size: 2rem;
    font-weight: 400;
    color: var(--text-primary);
    letter-spacing: 0.05em;
}

.subtitle {
    font-size: 0.8rem;
    color: var(--text-secondary);
    font-style: italic;
    margin-top: -5px;
}

.highlight {
    color: var(--accent-red);
}

.controls-wrapper {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    flex-grow: 1;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 0.8rem;
}

label {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* Element Pool */
.element-pool {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    padding: 10px;
    background: rgba(255, 255, 255, 0.5);
    border-radius: 12px;
    border: 1px solid rgba(139, 0, 0, 0.1);
}

.element-item {
    padding: 6px 12px;
    background: #fff;
    border-radius: 20px;
    font-size: 0.9rem;
    cursor: grab;
    box-shadow: var(--shadow-sm);
    border: 1px solid rgba(139, 0, 0, 0.1);
    transition: all 0.2s ease;
}

.element-item:hover {
    transform: translateY(-2px);
    border-color: var(--accent-red);
    color: var(--accent-red);
}

.element-item:active {
    cursor: grabbing;
}

.hint-text {
    font-size: 0.75rem;
    color: var(--text-secondary);
    font-style: italic;
}

/* Operations Grid */
.ops-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
}

/* Info Panel */
.info-panel {
    background: rgba(255, 255, 255, 0.5);
    padding: 12px;
    border-radius: 12px;
    border: 1px solid rgba(139, 0, 0, 0.1);
}

.info-panel h3 {
    font-size: 1rem;
    color: var(--accent-red);
    margin-bottom: 6px;
    font-weight: 700;
}

.info-panel p {
    font-size: 0.85rem;
    line-height: 1.5;
    color: var(--text-primary);
}

/* Buttons */
.actions-footer {
    display: flex;
    gap: 10px;
    margin-top: auto;
}

.apple-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 20px;
    border-radius: 12px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    border: none;
    font-family: var(--font-family);
    width: 100%;
}

.op-btn {
    background: #fff;
    color: var(--text-primary);
    box-shadow: var(--shadow-sm);
    border: 1px solid rgba(139, 0, 0, 0.1);
}

.op-btn:hover {
    background: var(--accent-red);
    color: white;
    border-color: var(--accent-red);
}

.op-btn.active {
    background: var(--accent-red);
    color: white;
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.1);
}

.danger-btn {
    background: rgba(139, 0, 0, 0.1);
    color: var(--text-primary);
}

.danger-btn:hover {
    background: rgba(139, 0, 0, 0.2);
}

/* Main Stage */
.visualizer-stage {
    flex-grow: 1;
    padding: 2rem;
    display: flex;
    justify-content: center;
    align-items: center;
}

.glass-pane {
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.4);
    border-radius: 16px;
    box-shadow: inset 0 0 20px rgba(255, 255, 255, 0.5);
    border: 1px solid rgba(255, 255, 255, 0.4);
    padding: 2rem;
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.stage-header {
    text-align: center;
    margin-bottom: 2rem;
}

.stage-header h2 {
    font-size: 1.8rem;
    color: var(--accent-red);
    margin-bottom: 0.5rem;
    font-family: var(--font-title);
}

.stage-header p {
    font-size: 1.1rem;
    color: var(--text-secondary);
    font-family: 'Courier New', monospace;
    font-weight: 600;
}

/* Venn Diagram */
.venn-container {
    flex-grow: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
}

.venn-wrapper {
    position: relative;
    width: 500px;
    height: 350px;
}

.venn-circle {
    position: absolute;
    width: 300px;
    height: 300px;
    border-radius: 50%;
    border: 2px solid rgba(139, 0, 0, 0.3);
    background: rgba(214, 59, 29, 0.05);
    display: flex;
    justify-content: center;
    align-items: flex-start;
    padding-top: 20px;
    transition: all 0.3s ease;
}

.set-a {
    left: 0;
    top: 0;
    z-index: 1;
}

.set-b {
    right: 0;
    top: 0;
    z-index: 1;
}

.set-label {
    font-weight: 700;
    color: var(--text-primary);
    font-size: 1.2rem;
    pointer-events: none;
}

.set-content {
    position: absolute;
    top: 50px;
    bottom: 50px;
    left: 50px;
    right: 50px;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    align-items: center;
    gap: 8px;
    pointer-events: none;
}

/* Overlap Area Logic - Visualized by CSS blend modes or positioning */
.venn-intersect {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    width: 100px;
    /* Approximate intersection width */
    height: 200px;
    z-index: 0;
    pointer-events: none;
}

/* Highlighting */
.venn-circle.highlight {
    background: rgba(214, 59, 29, 0.2);
    box-shadow: 0 0 20px rgba(214, 59, 29, 0.1);
    border-color: var(--accent-red);
}

.venn-circle.dim {
    opacity: 0.3;
}

/* Dropped Elements */
.dropped-item {
    font-size: 1.5rem;
    animation: popIn 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

@keyframes popIn {
    from {
        transform: scale(0);
    }

    to {
        transform: scale(1);
    }
}

/* Result Badge */
.result-badge {
    position: absolute;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--accent-red);
    color: white;
    padding: 8px 24px;
    border-radius: 20px;
    font-size: 1.2rem;
    font-weight: 700;
    box-shadow: var(--shadow-md);
    font-family: var(--font-title);
    transition: all 0.3s ease;
}

.result-badge.hidden {
    opacity: 0;
    transform: translate(-50%, 20px);
}

@media (max-width: 1024px) {
    .app-container {
        flex-direction: column;
        width: 96vw;
        height: 96vh;
    }

    .sidebar {
        width: 100%;
        max-height: 45vh;
    }

    .venn-wrapper {
        transform: scale(0.7);
    }
}