:root {
            --primary-color: #4361ee;
            --primary-light: #4895ef;
            --primary-dark: #3a0ca3;
            --secondary-color: #f72585;
            --success-color: #4cc9f0;
            --error-color: #f72585;
            --warning-color: #f8961e;
            --text-color: #2b2d42;
            --text-light: #8d99ae;
            --bg-color: #f8f9fa;
            --card-color: #ffffff;
            --border-color: #e9ecef;
            --shadow-color: rgba(0, 0, 0, 0.1);
            --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
        }
        
        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }
        
        body {
            font-family: 'Poppins', sans-serif;
            background-color: var(--bg-color);
            color: var(--text-color);
            line-height: 1.6;
            padding: 20px;
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
        }
        
        .container {
            width: 100%;
            max-width: 900px;
            background-color: var(--card-color);
            border-radius: 16px;
            box-shadow: 0 10px 30px var(--shadow-color);
            padding: 40px;
            margin: 20px 0;
            transition: var(--transition);
            position: relative;
            overflow: hidden;
        }
        
        .container::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 8px;
            background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
        }
        
        h1 {
            color: var(--primary-color);
            text-align: center;
            margin-bottom: 8px;
            font-weight: 600;
            font-size: 2.2rem;
            position: relative;
            display: inline-block;
            width: 100%;
        }
        
        h1::after {
            content: '';
            display: block;
            width: 60px;
            height: 4px;
            background: var(--secondary-color);
            margin: 10px auto;
            border-radius: 2px;
        }
        
        .subtitle {
            text-align: center;
            color: var(--text-light);
            margin-bottom: 30px;
            font-size: 1rem;
            font-weight: 400;
        }
        
        .equation-container {
            margin-bottom: 30px;
        }
        
        .equation {
            display: flex;
            align-items: center;
            margin-bottom: 20px;
            flex-wrap: wrap;
            position: relative;
            padding: 15px;
            border-radius: 12px;
            background-color: rgba(67, 97, 238, 0.05);
            border: 1px solid rgba(67, 97, 238, 0.1);
        }
        
        .equation:hover {
            background-color: rgba(67, 97, 238, 0.08);
        }
        
        .equation-label {
            font-weight: 500;
            margin-right: 15px;
            width: 90px;
            color: var(--primary-dark);
            font-size: 1.1rem;
        }
        
        .equation-input {
            width: 70px;
            margin: 0 8px;
            padding: 12px;
            text-align: center;
            border: 2px solid var(--border-color);
            border-radius: 8px;
            font-size: 1rem;
            font-weight: 500;
            transition: var(--transition);
            background-color: white;
        }
        
        .equation-input:focus {
            border-color: var(--primary-color);
            outline: none;
            box-shadow: 0 0 0 3px rgba(67, 97, 238, 0.2);
            transform: translateY(-2px);
        }
        
        .equation-input::placeholder {
            color: var(--text-light);
            opacity: 0.6;
        }
        
        .variable {
            font-weight: 600;
            color: var(--primary-color);
            margin: 0 5px;
            font-size: 1.1rem;
        }
        
        .button-group {
            display: flex;
            flex-wrap: wrap;
            justify-content: center;
            gap: 15px;
            margin: 30px 0;
        }
        
        button {
            background-color: var(--primary-color);
            color: white;
            border: none;
            padding: 14px 30px;
            border-radius: 8px;
            cursor: pointer;
            font-size: 1rem;
            font-weight: 500;
            transition: var(--transition);
            box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
            display: flex;
            align-items: center;
            justify-content: center;
            min-width: 180px;
        }
        
        button:hover {
            background-color: var(--primary-dark);
            transform: translateY(-3px);
            box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
        }
        
        button:active {
            transform: translateY(0);
        }
        
        button i {
            margin-right: 8px;
        }
        
        .result {
            margin-top: 30px;
            padding: 25px;
            border-radius: 12px;
            display: none;
            animation: fadeIn 0.5s ease;
            position: relative;
            overflow: hidden;
        }
        
        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(20px); }
            to { opacity: 1; transform: translateY(0); }
        }
        
        .error {
            background-color: rgba(248, 37, 133, 0.08);
            color: var(--error-color);
            border-left: 4px solid var(--error-color);
        }
        
        .success {
            background-color: rgba(76, 201, 240, 0.08);
            color: var(--text-color);
            border-left: 4px solid var(--success-color);
        }
        
        .formula {
            font-family: 'Courier New', Courier, monospace;
            background-color: rgba(0, 0, 0, 0.05);
            padding: 8px 12px;
            border-radius: 6px;
            font-size: 1rem;
            color: var(--text-color);
            display: inline-block;
            margin: 5px 0;
        }
        
        .solution {
            font-size: 1.3rem;
            margin: 20px 0;
            font-weight: 600;
            display: flex;
            flex-direction: column;
            gap: 10px;
        }
        
        .solution span {
            display: flex;
            align-items: center;
            gap: 10px;
        }
        
        .steps {
            margin-top: 20px;
            border-top: 1px dashed var(--border-color);
            padding-top: 20px;
        }
        
        .step {
            margin-bottom: 15px;
            font-size: 0.95rem;
            line-height: 1.7;
            padding-left: 15px;
            border-left: 3px solid var(--primary-light);
        }
        
        .step strong {
            color: var(--primary-dark);
            font-weight: 500;
        }
        
        .reset-btn {
            background-color: var(--text-light);
            margin-top: 20px;
            width: auto;
            padding: 10px 20px;
            font-size: 0.9rem;
            min-width: auto;
        }
        
        .reset-btn:hover {
            background-color: var(--text-color);
        }
        
        .example-btn {
            background-color: transparent;
            color: var(--primary-color);
            border: 2px solid var(--primary-color);
            margin: 0;
            padding: 12px 20px;
            font-size: 0.95rem;
            min-width: auto;
        }
        
        .example-btn:hover {
            background-color: rgba(67, 97, 238, 0.1);
        }
        
        .examples-dropdown {
            display: none;
            margin-top: 15px;
            padding: 0;
            background-color: white;
            border-radius: 8px;
            box-shadow: 0 5px 15px var(--shadow-color);
            width: 100%;
            overflow: hidden;
        }
        
        .example-item {
            padding: 12px 20px;
            cursor: pointer;
            border-bottom: 1px solid var(--border-color);
            transition: var(--transition);
            font-size: 0.95rem;
        }
        
        .example-item:hover {
            background-color: rgba(67, 97, 238, 0.1);
            color: var(--primary-color);
            padding-left: 25px;
        }
        
        .example-item:last-child {
            border-bottom: none;
        }
        
        .result h3 {
            margin-bottom: 15px;
            color: var(--primary-dark);
            font-size: 1.3rem;
            display: flex;
            align-items: center;
            gap: 10px;
        }
        
        .result h3::before {
            content: '';
            display: block;
            width: 20px;
            height: 20px;
            background-color: var(--primary-color);
            mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='currentColor' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M22 11.08V12a10 10 0 1 1-5.93-9.14'%3E%3C/path%3E%3Cpolyline points='22 4 12 14.01 9 11.01'%3E%3C/polyline%3E%3C/svg%3E");
            mask-repeat: no-repeat;
            mask-position: center;
            background-color: var(--primary-color);
        }
        
        .success h3::before {
            background-color: var(--success-color);
        }
        
        .error h3::before {
            background-color: var(--error-color);
        }
        
        .graph-container {
            margin-top: 30px;
            width: 100%;
            height: 400px;
            position: relative;
            border-radius: 12px;
            overflow: hidden;
            border: 1px solid var(--border-color);
            background-color: white;
        }
        
        .graph-placeholder {
            display: flex;
            align-items: center;
            justify-content: center;
            height: 100%;
            color: var(--text-light);
            font-size: 1rem;
        }
        
        @media (max-width: 768px) {
            .container {
                padding: 30px 20px;
            }
            
            h1 {
                font-size: 1.8rem;
            }
            
            .equation {
                padding: 12px;
            }
            
            .equation-label {
                width: 100%;
                margin-bottom: 10px;
            }
            
            .equation-input {
                width: 60px;
                margin: 5px;
            }
            
            .button-group {
                flex-direction: column;
                align-items: center;
            }
            
            button {
                width: 100%;
            }
            
            .graph-container {
                height: 300px;
            }
        }
        
        @media (max-width: 480px) {
            .container {
                padding: 25px 15px;
                border-radius: 12px;
            }
            
            .equation-input {
                width: 50px;
                padding: 10px;
                font-size: 0.9rem;
            }
            
            .variable {
                font-size: 1rem;
            }
            
            .result {
                padding: 20px 15px;
            }
            
            .graph-container {
                height: 250px;
            }
        }