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

:root {
    --primary-color: #2c3e50;
    --accent-color: #9b59b6;
    --light-accent: #bb8fce;
    --dark-accent: #7d3c98;
    --success-color: #27ae60;
    --warning-color: #f39c12;
    --danger-color: #e74c3c;
    --light-bg: #ecf0f1;
    --medium-bg: #bdc3c7;
    --dark-bg: #1a1a2e;
    --text-color: #2c3e50;
    --light-text: #ecf0f1;
    --border-radius: 8px;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.colloid-brownian-container {
    max-width: 1600px;
    margin: 0 auto;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
    overflow: hidden;
}

/* Header */
header {
    background: linear-gradient(135deg, #9b59b6 0%, #8e44ad 100%);
    color: white;
    padding: 40px 30px;
    text-align: center;
}

header h1 {
    font-size: 2.5em;
    margin-bottom: 10px;
    font-weight: 300;
    letter-spacing: 1px;
}

header .subtitle {
    font-size: 1.1em;
    opacity: 0.9;
    max-width: 900px;
    margin: 0 auto;
}

/* Main Content */
main {
    padding: 30px;
}

/* Mode Selector */
.mode-selector {
    background: var(--light-bg);
    padding: 20px;
    border-radius: var(--border-radius);
    margin-bottom: 30px;
}

.mode-selector h3 {
    margin-bottom: 15px;
    color: var(--primary-color);
}

.mode-options {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.mode-btn {
    padding: 12px 24px;
    border: 2px solid var(--accent-color);
    background: white;
    color: var(--accent-color);
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1em;
    flex: 1;
    min-width: 150px;
}

.mode-btn:hover {
    background: var(--accent-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.mode-btn.active {
    background: var(--accent-color);
    color: white;
    font-weight: 600;
}

/* Canvas Wrapper */
.canvas-wrapper {
    display: grid;
    grid-template-columns: 1fr 380px;
    gap: 20px;
    margin-bottom: 30px;
}

.main-canvas-container {
    background: var(--dark-bg);
    border-radius: var(--border-radius);
    padding: 20px;
    box-shadow: var(--shadow);
    position: relative;
    min-height: 600px;
}

#mainCanvas {
    width: 100%;
    height: 600px;
    background: radial-gradient(ellipse at center, #2d2d44 0%, #1a1a2e 100%);
    border-radius: var(--border-radius);
    display: block;
}

.canvas-overlay {
    position: absolute;
    top: 20px;
    left: 20px;
    right: 20px;
    display: flex;
    justify-content: space-between;
    pointer-events: none;
}

.microscope-info {
    background: rgba(0, 0, 0, 0.7);
    color: white;
    padding: 10px 15px;
    border-radius: 5px;
    font-size: 0.9em;
    pointer-events: none;
}

.microscope-info span {
    margin-right: 20px;
}

/* Stats Panel */
.stats-panel {
    background: var(--light-bg);
    padding: 20px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.stats-panel h4 {
    margin-bottom: 15px;
    color: var(--primary-color);
    font-size: 1.1em;
}

.stats-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
    margin-bottom: 20px;
}

.stat-item {
    background: white;
    padding: 12px;
    border-radius: var(--border-radius);
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05);
}

.stat-label {
    display: block;
    font-size: 0.85em;
    color: var(--dark-accent);
    margin-bottom: 5px;
}

.stat-value {
    display: block;
    font-size: 1.5em;
    font-weight: 600;
    color: var(--accent-color);
}

.stat-unit {
    font-size: 0.9em;
    color: var(--medium-bg);
    margin-left: 5px;
}

/* Formula Display */
.formula-display {
    background: white;
    padding: 15px;
    border-radius: var(--border-radius);
    border-left: 4px solid var(--accent-color);
}

.formula-main {
    font-size: 1.3em;
    margin-bottom: 10px;
    color: var(--primary-color);
}

.formula-calculation {
    font-size: 0.9em;
    color: var(--dark-accent);
    font-style: italic;
}

/* Chart Panel */
.chart-panel {
    background: var(--light-bg);
    padding: 20px;
    border-radius: var(--border-radius);
    margin-bottom: 30px;
}

.chart-panel h4 {
    margin-bottom: 15px;
    color: var(--primary-color);
}

.chart-container {
    background: white;
    padding: 15px;
    border-radius: var(--border-radius);
    height: 300px;
    margin-bottom: 15px;
}

.chart-container canvas {
    width: 100%;
    height: 100%;
}

.chart-info {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
}

.info-item {
    background: white;
    padding: 10px 15px;
    border-radius: var(--border-radius);
    font-size: 0.9em;
}

/* Controls Panel */
.controls-panel {
    background: var(--light-bg);
    padding: 25px;
    border-radius: var(--border-radius);
    margin-bottom: 30px;
}

.controls-panel h3 {
    margin-bottom: 20px;
    color: var(--primary-color);
}

.controls-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
    margin-bottom: 25px;
}

.control-group {
    background: white;
    padding: 15px;
    border-radius: var(--border-radius);
}

.control-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--primary-color);
}

.control-group select {
    width: 100%;
    padding: 10px;
    border: 2px solid var(--medium-bg);
    border-radius: var(--border-radius);
    font-size: 1em;
    background: white;
    cursor: pointer;
    transition: border-color 0.3s ease;
}

.control-group select:focus {
    outline: none;
    border-color: var(--accent-color);
}

.control-group input[type="range"] {
    width: 100%;
    margin: 10px 0;
    cursor: pointer;
}

.range-info {
    font-size: 0.85em;
    color: var(--dark-accent);
    margin-top: 5px;
}

/* Button Group */
.button-group {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 25px;
}

.control-button {
    padding: 12px 20px;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 1em;
    transition: all 0.3s ease;
    font-weight: 500;
}

.control-button.start {
    background: var(--success-color);
    color: white;
}

.control-button.start:hover {
    background: #229954;
}

.control-button.pause {
    background: var(--warning-color);
    color: white;
}

.control-button.pause:hover {
    background: #e67e22;
}

.control-button.reset {
    background: var(--danger-color);
    color: white;
}

.control-button.reset:hover {
    background: #c0392b;
}

.control-button.capture {
    background: var(--accent-color);
    color: white;
}

.control-button.capture:hover {
    background: var(--dark-accent);
}

/* Options Section */
.options-section {
    background: white;
    padding: 20px;
    border-radius: var(--border-radius);
    margin-bottom: 25px;
}

.options-section h4 {
    margin-bottom: 15px;
    color: var(--primary-color);
}

.options-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
}

.option-item {
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    padding: 8px;
    border-radius: var(--border-radius);
    transition: background-color 0.2s;
}

.option-item:hover {
    background: var(--light-bg);
}

.option-item input[type="checkbox"] {
    width: 18px;
    height: 18px;
    cursor: pointer;
}

.option-item span {
    font-size: 0.95em;
}

/* Presets Panel */
.presets-panel {
    background: white;
    padding: 20px;
    border-radius: var(--border-radius);
}

.presets-panel h4 {
    margin-bottom: 15px;
    color: var(--primary-color);
}

.preset-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.preset-btn {
    padding: 10px 18px;
    border: 2px solid var(--accent-color);
    background: white;
    color: var(--accent-color);
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.95em;
}

.preset-btn:hover {
    background: var(--accent-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

/* Comparison Panel */
.comparison-panel {
    background: var(--light-bg);
    padding: 25px;
    border-radius: var(--border-radius);
    margin-bottom: 30px;
}

.comparison-panel h3 {
    margin-bottom: 20px;
    color: var(--primary-color);
}

.comparison-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 25px;
    margin-bottom: 25px;
}

.size-item {
    background: white;
    padding: 20px;
    border-radius: var(--border-radius);
    text-align: center;
    transition: transform 0.3s ease;
}

.size-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow);
}

.size-visual {
    width: 80px;
    height: 80px;
    margin: 0 auto 15px;
    border-radius: 50%;
    position: relative;
}

.size-visual.water-molecule {
    background: radial-gradient(circle, #3498db 2px, transparent 2px);
    background-size: 20px 20px;
    background-position: center;
}

.size-visual.nanoparticle {
    background: radial-gradient(circle, #3498db 8px, transparent 8px);
    background-size: 20px 20px;
    background-position: center;
}

.size-visual.colloid {
    background: radial-gradient(circle, #3498db 15px, transparent 15px);
    background-size: 40px 40px;
    background-position: center;
}

.size-visual.large-colloid {
    background: radial-gradient(circle, #3498db 30px, transparent 30px);
    background-size: 70px 70px;
    background-position: center;
}

.size-item h4 {
    margin-bottom: 8px;
    color: var(--primary-color);
    font-size: 1.1em;
}

.size-value {
    font-size: 1.3em;
    font-weight: 600;
    color: var(--accent-color);
    margin-bottom: 8px;
}

.size-desc {
    font-size: 0.85em;
    color: var(--dark-accent);
    line-height: 1.4;
}

.scale-explanation {
    background: white;
    padding: 15px;
    border-radius: var(--border-radius);
    border-left: 4px solid var(--accent-color);
}

.scale-explanation p {
    color: var(--primary-color);
    font-style: italic;
}

/* Applications Panel */
.applications-panel {
    background: var(--light-bg);
    padding: 25px;
    border-radius: var(--border-radius);
    margin-bottom: 30px;
}

.applications-panel h3 {
    margin-bottom: 20px;
    color: var(--primary-color);
}

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

.application-card {
    background: white;
    padding: 20px;
    border-radius: var(--border-radius);
    text-align: center;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.application-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.15);
}

.application-icon {
    font-size: 2.5em;
    margin-bottom: 15px;
}

.application-card h4 {
    margin-bottom: 10px;
    color: var(--primary-color);
}

.application-card p {
    font-size: 0.9em;
    color: var(--dark-accent);
    line-height: 1.5;
}

/* Explanation Section */
.explanation {
    background: var(--light-bg);
    padding: 30px;
    border-radius: var(--border-radius);
}

.explanation h2 {
    color: var(--primary-color);
    margin-bottom: 20px;
    border-bottom: 3px solid var(--accent-color);
    padding-bottom: 10px;
}

.explanation h3 {
    color: var(--dark-accent);
    margin-top: 25px;
    margin-bottom: 15px;
}

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

.explanation strong {
    color: var(--accent-color);
}

/* Responsive Design */
@media (max-width: 1200px) {
    .canvas-wrapper {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    header h1 {
        font-size: 1.8em;
    }

    header .subtitle {
        font-size: 1em;
    }

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

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

    .button-group {
        flex-direction: column;
    }

    .control-button {
        width: 100%;
    }

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

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

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

/* Loading animation */
@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

.loading {
    animation: pulse 2s ease-in-out infinite;
}