: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;

    --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;
}

.control-group.hidden {
    display: none;
}

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

/* Mode Tabs */
.mode-tabs {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
    background: rgba(139, 0, 0, 0.05);
    padding: 4px;
    border-radius: 12px;
}

.mode-tab {
    padding: 8px;
    text-align: center;
    border-radius: 8px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    color: var(--text-secondary);
}

.mode-tab.active {
    background: #fff;
    color: var(--accent-red);
    box-shadow: var(--shadow-sm);
}

/* Inputs */
.apple-select {
    width: 100%;
    padding: 10px;
    border-radius: 10px;
    border: 1px solid rgba(139, 0, 0, 0.2);
    background: #fff;
    color: var(--text-primary);
    font-family: var(--font-family);
    font-size: 1rem;
    outline: none;
}

input[type=range] {
    appearance: none;
    width: 100%;
    background: transparent;
}

input[type=range]::-webkit-slider-thumb {
    -webkit-appearance: none;
    height: 20px;
    width: 20px;
    border-radius: 50%;
    background: var(--accent-red);
    cursor: pointer;
    margin-top: -8px;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
    border: 2px solid #fff;
    transition: transform 0.1s;
}

input[type=range]::-webkit-slider-thumb:hover {
    transform: scale(1.1);
}

input[type=range]::-webkit-slider-runnable-track {
    width: 100%;
    height: 4px;
    cursor: pointer;
    background: rgba(139, 0, 0, 0.1);
    border-radius: 2px;
}

.slider-label {
    font-size: 0.9rem;
    color: var(--text-primary);
    font-weight: 600;
    text-align: right;
}

.slider-label span {
    color: var(--accent-red);
    font-weight: 700;
    font-size: 1.1rem;
}

/* 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%;
}

.action-btn {
    background: var(--accent-red);
    color: white;
    box-shadow: var(--shadow-md);
}

.action-btn:hover {
    background: var(--accent-hover);
    transform: translateY(-1px);
}

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

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

.apple-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

/* 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: 0.9rem;
    color: var(--text-secondary);
}

.visualization-area {
    flex-grow: 1;
    overflow-y: auto;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    padding: 1rem;
}

/* Euler Grid */
.coprime-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(60px, 1fr));
    gap: 12px;
    width: 100%;
    max-width: 800px;
}

.number-card {
    aspect-ratio: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    border-radius: 12px;
    background: rgba(255, 255, 255, 0.6);
    border: 2px solid transparent;
    transition: all 0.3s ease;
    font-weight: 700;
    font-size: 1.2rem;
    color: var(--text-secondary);
}

.number-card.coprime {
    background: #fff;
    border-color: var(--accent-gold);
    color: var(--accent-red);
    box-shadow: var(--shadow-md);
    transform: scale(1.05);
}

.number-card.non-coprime {
    opacity: 0.5;
    background: rgba(0, 0, 0, 0.02);
}

.sz-badge {
    font-size: 0.6rem;
    margin-top: 4px;
    color: var(--text-primary);
    font-weight: normal;
}

/* Fermat Sequence */
.fermat-sequence {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    justify-content: center;
    align-items: center;
    max-width: 900px;
}

.sequence-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 12px;
    background: #fff;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    min-width: 80px;
    border: 1px solid rgba(139, 0, 0, 0.1);
    transition: all 0.3s ease;
}

.sequence-item.highlight {
    border-color: var(--accent-red);
    background: #fff5f5;
    transform: scale(1.1);
    box-shadow: var(--shadow-md);
}

.seq-exp {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-bottom: 4px;
}

.seq-val {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--text-primary);
}

/* Result Panel */
.result-panel {
    margin-top: auto;
    background: rgba(255, 255, 255, 0.6);
    padding: 16px;
    border-radius: 12px;
    display: flex;
    justify-content: space-around;
    border: 1px solid rgba(139, 0, 0, 0.1);
}

.result-panel.hidden {
    display: none;
}

.result-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
}

.result-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-transform: uppercase;
}

.result-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-red);
}

.political-text {
    font-family: var(--font-title);
    font-size: 1.2rem;
    color: var(--text-primary);
}

/* Animations */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.number-card,
.sequence-item {
    animation: fadeIn 0.4s ease forwards;
}