:root {
            --pastel-blue: #AEC6CF;
            --pastel-green: #B3E3BD;
            --pastel-lavender: #D5B9FF;
            --pastel-pink: #FFB3D8;
            --text-dark: #374151;
            --bg-light: #F9FAFB;
        }
        body {
            font-family: 'Inter', sans-serif;
            background-color: var(--bg-light);
            color: var(--text-dark);
        }
        .tab-button.active {
            border-bottom: 4px solid var(--pastel-lavender);
            color: var(--text-dark);
            background-color: white;
        }
        .sidebar {
            background-color: var(--pastel-blue);
            min-height: 100%;
        }
        .control-button {
            transition: background-color 0.2s, transform 0.1s;
            background-color: var(--pastel-lavender);
            color: white;
            font-weight: 600;
            box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.06);
        }
        .control-button:hover:not(:disabled) {
            background-color: #B295E0;
            transform: translateY(-1px);
        }
        .control-button:disabled {
            opacity: 0.5;
            cursor: not-allowed;
        }
        .step-highlight {
            background-color: var(--pastel-pink);
            padding: 4px 8px;
            border-radius: 6px;
            font-weight: 600;
            color: var(--text-dark);
        }
        #graph-placeholder {
            background-color: rgba(255, 255, 255, 0.85);
        }
        input[type="range"] {
            -webkit-appearance: none;
            width: 100%;
            height: 10px;
            background: #f0e6ff;
            border-radius: 5px;
            outline: none;
            opacity: 0.9;
            transition: opacity .2s;
        }
        input[type="range"]::-webkit-slider-thumb {
            -webkit-appearance: none;
            appearance: none;
            width: 20px;
            height: 20px;
            background: var(--pastel-lavender);
            border-radius: 50%;
            cursor: pointer;
            box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
        }
        input[type="range"]::-moz-range-thumb {
            width: 20px;
            height: 20px;
            background: var(--pastel-lavender);
            border-radius: 50%;
            cursor: pointer;
            box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
        }
        .error-message {
            background-color: #FEE2E2;
            border: 1px solid #FCA5A5;
            color: #DC2626;
            padding: 10px;
            border-radius: 6px;
            margin: 10px 0;
        }
        .success-message {
            background-color: #D1FAE5;
            border: 1px solid #A7F3D0;
            color: #059669;
            padding: 10px;
            border-radius: 6px;
            margin: 10px 0;
        }
        .modal {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background-color: rgba(0, 0, 0, 0.5);
            z-index: 1000;
            justify-content: center;
            align-items: center;
        }
        .modal-content {
            background-color: white;
            padding: 2rem;
            border-radius: 12px;
            max-width: 500px;
            width: 90%;
            max-height: 80vh;
            overflow-y: auto;
            box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
        }
        .example-item {
            padding: 12px;
            margin: 8px 0;
            border-radius: 8px;
            cursor: pointer;
            transition: all 0.2s;
            border: 1px solid #e5e7eb;
        }
        .example-item:hover {
            background-color: #f3f4f6;
            border-color: var(--pastel-lavender);
            transform: translateY(-2px);
        }
        .example-item.derivative {
            border-left: 4px solid #3b82f6;
        }
        .example-item.integral {
            border-left: 4px solid #10b981;
        }
        .copy-btn {
            background-color: #e0e7ff;
            color: #4f46e5;
            padding: 4px 12px;
            border-radius: 6px;
            font-size: 0.875rem;
            transition: all 0.2s;
        }
        .copy-btn:hover {
            background-color: #c7d2fe;
        }
        .examples-dropdown {
            position: relative;
            display: inline-block;
        }
        .examples-dropdown-content {
            display: none;
            position: absolute;
            background-color: white;
            min-width: 300px;
            box-shadow: 0 8px 16px rgba(0,0,0,0.1);
            z-index: 1;
            border-radius: 8px;
            padding: 1rem;
            margin-top: 8px;
        }
        .examples-dropdown:hover .examples-dropdown-content {
            display: block;
        }
        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(10px); }
            to { opacity: 1; transform: translateY(0); }
        }
        .animate-fadeIn {
            animation: fadeIn 0.3s ease-out;
        }