:root {
            --bg-dark: #121212;
            --bg-card: #1e1e1e;
            --accent: #ff7b00;
            --accent-light: #ff9a40;
            --text-primary: #ffffff;
            --text-secondary: #b0b0b0;
            --grid-line: rgba(255, 255, 255, 0.1);
            --grid-line-major: rgba(255, 255, 255, 0.2);
        }
        
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }
        
        body {
            background-color: var(--bg-dark);
            color: var(--text-primary);
            min-height: 100vh;
            overflow-x: hidden;
        }
        
        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 20px;
        }
        
        header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 16px 0;
            border-bottom: 1px solid rgba(255, 255, 255, 0.1);
            margin-bottom: 24px;
        }
        
        .logo {
            display: flex;
            align-items: center;
            gap: 12px;
        }
        
        .logo-icon {
            color: var(--accent);
            font-size: 24px;
        }
        
        .logo-text {
            font-size: 20px;
            font-weight: 600;
        }
        
        nav {
            display: flex;
            gap: 8px;
        }
        
        .tab {
            padding: 8px 16px;
            border-radius: 8px;
            cursor: pointer;
            transition: all 0.2s ease;
            font-weight: 500;
            position: relative;
            overflow: hidden;
        }
        
        .tab:hover {
            background-color: rgba(255, 123, 0, 0.1);
            color: var(--accent-light);
        }
        
        .tab.active {
            background-color: var(--accent);
            color: #000;
        }
        
        .tab-content {
            display: none;
        }
        
        .tab-content.active {
            display: block;
            animation: fadeIn 0.3s ease;
        }
        
        @keyframes fadeIn {
            from { opacity: 0; }
            to { opacity: 1; }
        }
        
        .card {
            background-color: var(--bg-card);
            border-radius: 12px;
            padding: 20px;
            margin-bottom: 20px;
            box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
        }
        
        .card-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 16px;
        }
        
        .card-title {
            font-size: 18px;
            font-weight: 600;
        }
        
        /* Simulator styles */
        .simulator-container {
            display: grid;
            grid-template-columns: 1fr 2fr;
            gap: 20px;
        }
        
        @media (max-width: 768px) {
            .simulator-container {
                grid-template-columns: 1fr;
            }
        }
        
        .simulation-view {
            height: 300px;
            background-color: rgba(0, 0, 0, 0.2);
            border-radius: 8px;
            position: relative;
            overflow: hidden;
        }
        
        .wall {
            position: absolute;
            left: 10%;
            top: 0;
            width: 10px;
            height: 100%;
            background-color: #444;
            border-right: 2px solid #666;
        }
        
        .spring {
            position: absolute;
            left: calc(10% + 10px);
            top: 50%;
            height: 8px;
            background-color: #888;
            transform: translateY(-50%);
        }
        
        .mass {
            position: absolute;
            width: 50px;
            height: 50px;
            background-color: var(--accent);
            border-radius: 50%;
            top: 50%;
            transform: translate(-50%, -50%);
            cursor: grab;
            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
            z-index: 10;
        }
        
        .mass:active {
            cursor: grabbing;
        }
        
        .mass-label {
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            font-weight: bold;
            color: #000;
        }
        
        .equilibrium-line {
            position: absolute;
            top: 0;
            height: 100%;
            width: 1px;
            background-color: rgba(255, 255, 255, 0.3);
            z-index: 5;
        }
        
        .controls {
            display: flex;
            flex-direction: column;
            gap: 16px;
        }
        
        .control-group {
            display: flex;
            flex-direction: column;
            gap: 8px;
        }
        
        .control-label {
            display: flex;
            justify-content: space-between;
            color: var(--text-secondary);
        }
        
        .slider-container {
            display: flex;
            align-items: center;
            gap: 10px;
        }
        
        .slider {
            flex: 1;
            -webkit-appearance: none;
            appearance: none;
            width: 100%;
            height: 4px;
            background: #333;
            border-radius: 4px;
            outline: none;
        }
        
        .slider::-webkit-slider-thumb {
            -webkit-appearance: none;
            appearance: none;
            width: 16px;
            height: 16px;
            border-radius: 50%;
            background: var(--accent);
            cursor: pointer;
            transition: all 0.2s ease;
        }
        
        .slider::-webkit-slider-thumb:hover {
            background: var(--accent-light);
            transform: scale(1.2);
        }
        
        .slider-value {
            width: 40px;
            text-align: right;
            color: var(--accent);
            font-weight: 500;
        }
        
        .button {
            padding: 10px 16px;
            border: none;
            border-radius: 8px;
            background-color: var(--accent);
            color: black;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.2s ease;
            margin-top: 8px;
        }
        
        .button:hover {
            background-color: var(--accent-light);
            transform: translateY(-1px);
        }
        
        .button-outline {
            background-color: transparent;
            border: 1px solid var(--accent);
            color: var(--accent);
        }
        
        .button-outline:hover {
            background-color: rgba(255, 123, 0, 0.1);
        }
        
        .button-sm {
            padding: 4px 8px;
            font-size: 14px;
        }
        
        .charts-container {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 20px;
            margin-top: 20px;
        }
        
        .chart-card {
            height: 250px;
            position: relative;
        }
        
        .chart-canvas {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
        }
        
        /* Learn tab styles */
        .learn-container {
            display: grid;
            grid-template-columns: 1fr 3fr;
            gap: 20px;
        }
        
        @media (max-width: 768px) {
            .learn-container {
                grid-template-columns: 1fr;
            }
        }
        
        .learn-nav {
            position: sticky;
            top: 20px;
        }
        
        .learn-nav-item {
            padding: 10px 16px;
            border-radius: 8px;
            cursor: pointer;
            transition: all 0.2s ease;
            margin-bottom: 8px;
        }
        
        .learn-nav-item:hover {
            background-color: rgba(255, 255, 255, 0.05);
        }
        
        .learn-nav-item.active {
            background-color: rgba(255, 123, 0, 0.2);
            color: var(--accent);
            font-weight: 500;
        }
        
        .learn-content {
            line-height: 1.6;
        }
        
        .learn-content h2 {
            margin: 24px 0 16px;
            color: var(--accent);
        }
        
        .learn-content h3 {
            margin: 20px 0 12px;
            color: var(--text-primary);
        }
        
        .learn-content p {
            margin-bottom: 16px;
            color: var(--text-secondary);
        }
        
        .learn-content ul, .learn-content ol {
            margin: 16px 0;
            padding-left: 24px;
            color: var(--text-secondary);
        }
        
        .learn-content li {
            margin-bottom: 8px;
        }
        
        .formula {
            background-color: rgba(0, 0, 0, 0.2);
            padding: 16px;
            border-radius: 8px;
            margin: 16px 0;
            display: flex;
            justify-content: center;
            align-items: center;
            font-family: 'Times New Roman', serif;
            color: var(--accent-light);
            font-size: 20px;
        }
        
        /* Settings tab styles */
        .settings-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
            gap: 20px;
        }
        
        .setting-item {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 12px 0;
            border-bottom: 1px solid rgba(255, 255, 255, 0.1);
        }
        
        .setting-label {
            color: var(--text-primary);
            font-weight: 500;
        }
        
        .setting-description {
            color: var(--text-secondary);
            font-size: 14px;
            margin-top: 4px;
        }
        
        .switch {
            position: relative;
            display: inline-block;
            width: 44px;
            height: 22px;
        }
        
        .switch input {
            opacity: 0;
            width: 0;
            height: 0;
        }
        
        .slider-toggle {
            position: absolute;
            cursor: pointer;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background-color: #333;
            -webkit-transition: .4s;
            transition: .4s;
            border-radius: 34px;
        }
        
        .slider-toggle:before {
            position: absolute;
            content: "";
            height: 18px;
            width: 18px;
            left: 3px;
            bottom: 2px;
            background-color: white;
            -webkit-transition: .4s;
            transition: .4s;
            border-radius: 50%;
        }
        
        input:checked + .slider-toggle {
            background-color: var(--accent);
        }
        
        input:focus + .slider-toggle {
            box-shadow: 0 0 1px var(--accent);
        }
        
        input:checked + .slider-toggle:before {
            -webkit-transform: translateX(20px);
            -ms-transform: translateX(20px);
            transform: translateX(20px);
        }
        
        .export-section {
            margin-top: 20px;
        }
        
        .file-input {
            display: none;
        }
        
        .file-input-label {
            display: inline-block;
            padding: 10px 16px;
            border: 1px solid var(--accent);
            border-radius: 8px;
            cursor: pointer;
            color: var(--accent);
            transition: all 0.2s ease;
            margin-right: 10px;
        }
        
        .file-input-label:hover {
            background-color: rgba(255, 123, 0, 0.1);
        }
        
        .data-capture {
            margin-top: 20px;
        }
        
        .captured-data {
            margin-top: 16px;
            max-height: 200px;
            overflow-y: auto;
        }
        
        table {
            width: 100%;
            border-collapse: collapse;
        }
        
        th {
            background-color: rgba(0, 0, 0, 0.2);
            text-align: left;
            padding: 8px;
            color: var(--text-secondary);
            font-weight: 500;
        }
        
        td {
            padding: 8px;
            border-bottom: 1px solid rgba(255, 255, 255, 0.05);
            color: var(--text-secondary);
        }
        
        .tooltip {
            position: relative;
            display: inline-block;
            margin-left: 4px;
        }
        
        .tooltip-icon {
            color: var(--text-secondary);
            cursor: pointer;
            font-size: 14px;
        }
        
        .tooltip-text {
            visibility: hidden;
            width: 200px;
            background-color: #333;
            color: var(--text-secondary);
            text-align: center;
            border-radius: 6px;
            padding: 8px;
            position: absolute;
            z-index: 1;
            bottom: 125%;
            left: 50%;
            transform: translateX(-50%);
            opacity: 0;
            transition: opacity 0.3s;
            font-size: 14px;
        }
        
        .tooltip:hover .tooltip-text {
            visibility: visible;
            opacity: 1;
        }