body {
            font-family: 'Nunito', Arial, sans-serif;
            background: linear-gradient(120deg, #f8fafc 0%, #e8f5e9 100%);
            min-height: 100vh;
            margin: 0;
            padding: 0;
        }
        .container {
            background: #fff;
            max-width: 420px;
            margin: 60px auto 0 auto;
            border-radius: 18px;
            box-shadow: 0 8px 32px rgba(60, 120, 60, 0.10);
            padding: 36px 30px 30px 30px;
        }
        h2 {
            text-align: center;
            color: #3a5a40;
            font-weight: 700;
            margin-bottom: 30px;
            letter-spacing: 0.5px;
        }
        form label {
            display: block;
            margin-bottom: 7px;
            color: #5a7d5a;
            font-size: 15.5px;
            font-weight: 600;
        }
        form input[type="text"], form input[type="date"] {
            width: 100%;
            padding: 12px 14px;
            margin-bottom: 20px;
            border: 1.5px solid #e0f2f1;
            border-radius: 8px;
            font-size: 15.5px;
            background: #f8fafc;
            transition: border 0.2s, box-shadow 0.2s;
            box-shadow: 0 1px 2px rgba(60,120,60,0.03);
        }
        form input[type="text"]:focus, form input[type="date"]:focus {
            border: 1.5px solid #81c784;
            outline: none;
            background: #fff;
            box-shadow: 0 2px 8px rgba(129,199,132,0.08);
        }
        button[type="submit"] {
            width: 100%;
            background: linear-gradient(90deg, #b7e4c7 0%, #81c784 100%);
            color: #234d20;
            font-weight: 700;
            border: none;
            border-radius: 8px;
            padding: 13px 0;
            font-size: 17px;
            cursor: pointer;
            transition: background 0.2s, transform 0.1s;
            box-shadow: 0 2px 12px rgba(129,199,132,0.10);
            letter-spacing: 0.5px;
        }
        button[type="submit"]:hover {
            background: linear-gradient(90deg, #81c784 0%, #b7e4c7 100%);
            transform: translateY(-2px) scale(1.02);
        }
        #result {
            margin-top: 28px;
            min-height: 40px;
            font-size: 15.5px;
        }
        .status-paid {
            color: #388e3c;
            font-weight: 700;
            margin-top: 10px;
        }
        .status-error {
            color: #e57373;
            font-weight: 700;
            margin-top: 10px;
        }
        pre {
            background: #f1f8e9;
            border-radius: 8px;
            padding: 14px;
            font-size: 14.5px;
            overflow-x: auto;
            border: 1px solid #e0f2f1;
        }
        .spinner {
            display: block;
            width: 32px;
            height: 32px;
            border: 4px solid #b7e4c7;
            border-radius: 50%;
            border-top: 4px solid #fff;
            animation: spin 1s linear infinite;
            margin: 18px auto 0 auto;
        }
        @keyframes spin {
            0% { transform: rotate(0deg);}
            100% { transform: rotate(360deg);}
        }
        @media (max-width: 600px) {
            .container {
                max-width: 98vw;
                margin: 18px 1vw 0 1vw;
                padding: 14px 5vw 14px 5vw;
                border-radius: 12px;
            }
            h2 {
                font-size: 1.15rem;
                margin-bottom: 16px;
            }
            form label {
                font-size: 14px;
            }
            form input[type="text"], form input[type="date"] {
                font-size: 14px;
                padding: 8px 8px;
            }
            button[type="submit"] {
                font-size: 15px;
                padding: 10px 0;
            }
            pre {
                font-size: 13px;
                padding: 8px;
            }
        }