:root {
    --primary-color: #3b82f6;
    --secondary-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --dark-bg: #1e293b;
    --darker-bg: #0f172a;
    --light-bg: #f8fafc;
    --border-color: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: linear-gradient(135deg, var(--darker-bg) 0%, var(--dark-bg) 100%);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.piezo-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
}

header {
    text-align: center;
    padding: 30px 20px;
    background: rgba(30, 41, 59, 0.8);
    border-radius: 15px;
    margin-bottom: 30px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
    backdrop-filter: blur(10px);
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 10px;
}

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

/* Mode Selection */
.mode-selection {
    display: flex;
    gap: 20px;
    margin-bottom: 30px;
    justify-content: center;
}

.mode-btn {
    flex: 1;
    max-width: 400px;
    padding: 20px;
    background: rgba(30, 41, 59, 0.8);
    border: 2px solid var(--border-color);
    border-radius: 12px;
    color: var(--text-primary);
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}

.mode-btn:hover {
    background: rgba(59, 130, 246, 0.2);
    border-color: var(--primary-color);
}

.mode-btn.active {
    background: rgba(59, 130, 246, 0.3);
    border-color: var(--primary-color);
    box-shadow: 0 0 20px rgba(59, 130, 246, 0.3);
}

.mode-icon {
    font-size: 1.5rem;
}

/* Main Layout */
.main-layout {
    display: grid;
    grid-template-columns: 1fr 400px;
    gap: 20px;
    margin-bottom: 30px;
}

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

.visualization-panel {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.crystal-display,
.charge-display {
    background: rgba(30, 41, 59, 0.8);
    border-radius: 12px;
    padding: 20px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
}

.crystal-display h3,
.charge-display h3 {
    color: var(--primary-color);
    margin-bottom: 15px;
    font-size: 1.2rem;
    font-weight: 600;
}

canvas {
    width: 100%;
    border-radius: 8px;
    background: rgba(15, 23, 42, 0.8);
    border: 1px solid var(--border-color);
}

#crystalCanvas {
    height: 400px;
}

#chargeCanvas {
    height: 200px;
}

.crystal-info,
.charge-legend {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    margin-top: 15px;
    padding: 15px;
    background: rgba(15, 23, 42, 0.5);
    border-radius: 8px;
}

.info-item {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.info-item span:last-child {
    color: var(--primary-color);
    font-weight: 600;
    font-size: 1.1rem;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
}

.legend-color {
    width: 20px;
    height: 20px;
    border-radius: 4px;
}

.legend-color.positive {
    background: var(--danger-color);
}

.legend-color.negative {
    background: var(--primary-color);
}

/* Controls Panel */
.controls-panel {
    background: rgba(30, 41, 59, 0.8);
    border-radius: 12px;
    padding: 20px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
}

.controls-panel h3 {
    color: var(--primary-color);
    margin-bottom: 20px;
    font-size: 1.2rem;
    font-weight: 600;
}

.control-group {
    margin-bottom: 25px;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--border-color);
}

.control-group:last-of-type {
    border-bottom: none;
}

.control-group h4 {
    color: var(--secondary-color);
    margin-bottom: 15px;
    font-size: 1rem;
    font-weight: 600;
}

.control-group label {
    display: block;
    margin-bottom: 8px;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.control-group input[type="range"] {
    width: 100%;
    height: 8px;
    border-radius: 4px;
    background: var(--border-color);
    outline: none;
    margin-bottom: 15px;
    -webkit-appearance: none;
}

.control-group input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    transition: all 0.2s ease;
}

.control-group input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.2);
    box-shadow: 0 0 10px rgba(59, 130, 246, 0.5);
}

.control-group input[type="range"]::-moz-range-thumb {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    border: none;
    transition: all 0.2s ease;
}

.control-group input[type="range"]::-moz-range-thumb:hover {
    transform: scale(1.2);
    box-shadow: 0 0 10px rgba(59, 130, 246, 0.5);
}

.control-group select {
    width: 100%;
    padding: 12px;
    background: rgba(15, 23, 42, 0.8);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-primary);
    font-size: 0.95rem;
    cursor: pointer;
    outline: none;
}

.control-group select:focus {
    border-color: var(--primary-color);
}

.checkbox-input {
    margin-right: 10px;
    width: 18px;
    height: 18px;
    accent-color: var(--primary-color);
}

.control-group label:has(.checkbox-input) {
    display: flex;
    align-items: center;
    margin-bottom: 10px;
    cursor: pointer;
}

/* Force Direction Buttons */
.force-direction {
    display: flex;
    gap: 10px;
    margin-top: 10px;
}

.direction-btn {
    flex: 1;
    padding: 10px;
    background: rgba(59, 130, 246, 0.2);
    border: 1px solid var(--primary-color);
    border-radius: 8px;
    color: var(--text-primary);
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.direction-btn:hover {
    background: rgba(59, 130, 246, 0.4);
}

.direction-btn:active {
    transform: scale(0.95);
}

/* Preset Buttons */
.preset-buttons {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 10px;
}

.preset-btn {
    padding: 12px;
    background: rgba(16, 185, 129, 0.2);
    border: 1px solid var(--secondary-color);
    border-radius: 8px;
    color: var(--text-primary);
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.preset-btn:hover {
    background: rgba(16, 185, 129, 0.4);
}

.preset-btn:active {
    transform: scale(0.95);
}

/* Formulas Section */
.formulas-section {
    margin-top: 20px;
    padding: 20px;
    background: rgba(15, 23, 42, 0.5);
    border-radius: 8px;
}

.formulas-section h3 {
    color: var(--primary-color);
    margin-bottom: 15px;
    font-size: 1.1rem;
}

.formula-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.formula-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px;
    background: rgba(30, 41, 59, 0.5);
    border-radius: 6px;
    border-left: 3px solid var(--secondary-color);
}

.formula-label {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.formula {
    color: var(--primary-color);
    font-family: 'Courier New', monospace;
    font-weight: 600;
    font-size: 1rem;
}

/* Applications Section */
.applications {
    background: rgba(30, 41, 59, 0.8);
    border-radius: 12px;
    padding: 30px;
    margin-bottom: 30px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
}

.applications h2 {
    color: var(--primary-color);
    margin-bottom: 25px;
    font-size: 1.5rem;
    font-weight: 600;
}

.applications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.application-card {
    background: rgba(15, 23, 42, 0.5);
    border-radius: 10px;
    padding: 20px;
    text-align: center;
    transition: all 0.3s ease;
    border: 1px solid transparent;
}

.application-card:hover {
    border-color: var(--primary-color);
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.3);
}

.app-icon {
    font-size: 3rem;
    margin-bottom: 15px;
}

.application-card h4 {
    color: var(--secondary-color);
    margin-bottom: 10px;
    font-size: 1.1rem;
}

.application-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.5;
}

/* Explanation Section */
.explanation {
    background: rgba(30, 41, 59, 0.8);
    border-radius: 12px;
    padding: 30px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
}

.explanation h2 {
    color: var(--primary-color);
    margin-bottom: 20px;
    font-size: 1.5rem;
    font-weight: 600;
}

.explanation h3 {
    color: var(--secondary-color);
    margin-top: 25px;
    margin-bottom: 15px;
    font-size: 1.2rem;
    font-weight: 600;
}

.explanation p {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 15px;
}

/* Responsive Design */
@media (max-width: 768px) {
    header h1 {
        font-size: 1.8rem;
    }

    .mode-selection {
        flex-direction: column;
    }

    .mode-btn {
        max-width: 100%;
    }

    .preset-buttons {
        grid-template-columns: 1fr;
    }

    .applications-grid {
        grid-template-columns: 1fr;
    }
}