:root {
            --primary: #4361ee;
            --primary-dark: #3a56d4;
            --secondary: #7209b7;
            --dark: #212529;
            --light: #f8f9fa;
            --success: #4cc9f0;
            --warning: #f72585;
            --gray: #6c757d;
            --border-radius: 12px;
            --box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
            --transition: all 0.3s ease;
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }

        body {
            background-color: #f5f7ff;
            color: var(--dark);
            line-height: 1.6;
            padding: 20px;
            min-height: 100vh;
        }

        .container {
            max-width: 1000px;
            margin: 0 auto;
        }

        header {
            text-align: center;
            margin-bottom: 40px;
            padding: 30px 20px;
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            color: white;
            border-radius: var(--border-radius);
            box-shadow: var(--box-shadow);
        }

        h1 {
            font-size: 2.5rem;
            margin-bottom: 10px;
        }

        .subtitle {
            font-size: 1.1rem;
            opacity: 0.9;
            max-width: 700px;
            margin: 0 auto;
        }

        .card {
            background: white;
            border-radius: var(--border-radius);
            box-shadow: var(--box-shadow);
            padding: 30px;
            margin-bottom: 30px;
            transition: var(--transition);
        }

        .card:hover {
            transform: translateY(-5px);
            box-shadow: 0 15px 40px rgba(0, 0, 0, 0.12);
        }

        .card-title {
            font-size: 1.5rem;
            margin-bottom: 20px;
            color: var(--primary);
            display: flex;
            align-items: center;
            gap: 10px;
        }

        .card-title i {
            font-size: 1.8rem;
        }

        .input-group {
            margin-bottom: 20px;
        }

        label {
            display: block;
            margin-bottom: 8px;
            font-weight: 600;
            color: var(--dark);
        }

        textarea, input, select {
            width: 100%;
            padding: 14px;
            border: 2px solid #e9ecef;
            border-radius: var(--border-radius);
            font-size: 1rem;
            transition: var(--transition);
        }

        textarea:focus, input:focus, select:focus {
            border-color: var(--primary);
            outline: none;
            box-shadow: 0 0 0 3px rgba(67, 97, 238, 0.2);
        }

        textarea {
            min-height: 150px;
            resize: vertical;
        }

        .shift-control {
            display: flex;
            align-items: center;
            gap: 15px;
            margin-bottom: 20px;
        }

        .shift-value {
            font-weight: bold;
            font-size: 1.2rem;
            color: var(--primary);
            min-width: 30px;
            text-align: center;
        }

        .btn {
            display: inline-block;
            background: var(--primary);
            color: white;
            border: none;
            padding: 14px 28px;
            border-radius: var(--border-radius);
            font-size: 1rem;
            font-weight: 600;
            cursor: pointer;
            transition: var(--transition);
            text-align: center;
        }

        .btn:hover {
            background: var(--primary-dark);
            transform: translateY(-2px);
        }

        .btn-secondary {
            background: var(--secondary);
        }

        .btn-secondary:hover {
            background: #6511a0;
        }

        .btn-full {
            width: 100%;
        }

        .action-buttons {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 15px;
            margin-top: 20px;
        }

        .result-container {
            position: relative;
        }

        .copy-btn {
            position: absolute;
            top: 10px;
            right: 10px;
            background: rgba(255, 255, 255, 0.9);
            border: none;
            padding: 8px 12px;
            border-radius: 6px;
            cursor: pointer;
            transition: var(--transition);
            display: flex;
            align-items: center;
            gap: 5px;
        }

        .copy-btn:hover {
            background: white;
            box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
        }

        .features {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 20px;
            margin-top: 40px;
        }

        .feature {
            background: white;
            padding: 25px;
            border-radius: var(--border-radius);
            box-shadow: var(--box-shadow);
            text-align: center;
            transition: var(--transition);
        }

        .feature:hover {
            transform: translateY(-5px);
        }

        .feature-icon {
            font-size: 2.5rem;
            color: var(--primary);
            margin-bottom: 15px;
        }

        .feature-title {
            font-size: 1.2rem;
            margin-bottom: 10px;
            color: var(--dark);
        }

        .feature-desc {
            color: var(--gray);
            font-size: 0.95rem;
        }

        footer {
            text-align: center;
            margin-top: 50px;
            padding: 20px;
            color: var(--gray);
            font-size: 0.9rem;
        }

        .history-section {
            margin-top: 30px;
        }

        .history-item {
            background: #f8f9fa;
            padding: 15px;
            border-radius: 8px;
            margin-bottom: 10px;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        .history-text {
            flex: 1;
            margin-right: 15px;
        }

        .history-actions {
            display: flex;
            gap: 10px;
        }

        .history-btn {
            background: none;
            border: none;
            cursor: pointer;
            color: var(--primary);
            font-size: 1.2rem;
        }

        @media (max-width: 768px) {
            .action-buttons {
                grid-template-columns: 1fr;
            }
            
            .shift-control {
                flex-direction: column;
                align-items: flex-start;
            }
            
            h1 {
                font-size: 2rem;
            }
        }

        /* Range slider styling */
        input[type="range"] {
            -webkit-appearance: none;
            width: 100%;
            height: 8px;
            border-radius: 5px;
            background: #e9ecef;
            outline: none;
        }

        input[type="range"]::-webkit-slider-thumb {
            -webkit-appearance: none;
            appearance: none;
            width: 22px;
            height: 22px;
            border-radius: 50%;
            background: var(--primary);
            cursor: pointer;
            transition: var(--transition);
        }

        input[type="range"]::-webkit-slider-thumb:hover {
            background: var(--primary-dark);
            transform: scale(1.1);
        }