body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            display: flex;
            justify-content: center;
            align-items: center;
            height: 100vh;
            margin: 0;
            background: linear-gradient(135deg, #007bff 25%, #00c4ff 100%);
            color: #fff;
            transition: background-color 0.5s ease;
        }

        .container {
            background-color: rgba(255, 255, 255, 0.9);
            padding: 20px;
            border-radius: 10px;
            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
            text-align: center;
            color: #333;
            max-width: 400px;
            width: 90%;
            transition: transform 0.5s ease;
        }

        .container.dark-mode {
            background-color: rgba(0, 0, 0, 0.9);
            color: #fff;
        }

        h2 {
            margin-bottom: 20px;
            font-size: 1.5rem;
            color: #007bff;
            font-weight: bold;
            font-style: italic;
            text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
            transition: color 0.5s ease;
        }

        input[type="date"] {
            padding: 8px;
            border: 1px solid #ccc;
            border-radius: 5px;
            width: calc(100% - 16px);
            margin-bottom: 10px;
            font-size: 1rem;
        }

        .result {
            font-size: 1rem;
            font-weight: bold;
            margin-top: 15px;
            color: #007bff;
            opacity: 0;
            transition: opacity 0.5s ease-in-out;
        }

        .result.show {
            opacity: 1;
        }

        .highlight {
            font-weight: bold;
            color: #28a745;
            font-size: 1.2rem;
            text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.2);
        }

        hr {
            border: none;
            border-top: 1px solid #007bff;
            width: 100%;
            margin: 20px 0;
        }

        .copy-button, .clear-button {
            padding: 8px;
            border-radius: 5px;
            border: none;
            cursor: pointer;
            margin-top: 10px;
            display: inline-flex;
            align-items: center;
            font-size: 1rem;
            transition: background-color 0.3s;
        }

        .copy-button {
            background-color: #28a745;
            color: #fff;
        }

        .copy-button:hover {
            background-color: #218838;
        }

        .clear-button {
            background-color: #dc3545;
            color: #fff;
        }

        .clear-button:hover {
            background-color: #c82333;
        }

        .dark-mode-toggle {
            position: absolute;
            top: 20px;
            right: 20px;
            background-color: #333;
            color: #fff;
            border: none;
            padding: 10px;
            border-radius: 5px;
            cursor: pointer;
            transition: background-color 0.3s;
        }

        .dark-mode-toggle:hover {
            background-color: #555;
        }

        .progress-container {
            margin-top: 20px;
            text-align: center;
            display: none;
        }

        .progress-circle {
            width: 80px;
            height: 80px;
            border-radius: 50%;
            background: conic-gradient(#28a745 calc(var(--progress) * 1%), #ddd 0);
            display: inline-block;
        }

        .copy-button i, .clear-button i {
            margin-right: 5px;
        }

        @media (max-width: 600px) {
            .container {
                width: 95%;
                padding: 15px;
            }

            h2 {
                font-size: 1.3rem;
            }

            .result {
                font-size: 0.9rem;
            }

            .highlight {
                font-size: 1.1rem;
            }

            .progress-circle {
                width: 60px;
                height: 60px;
            }
        }