body {
            font-family: 'Segoe UI', Arial, sans-serif;
            max-width: px;
            margin: 0 auto;
            padding: 20px;
            background-color: #f5f5f5;
            color: #333;
        }
        h1 {
            color: #1e3a8a;
            text-align: center;
            font-size: 24px;
            margin-bottom: 25px;
        }
        .union-jack {
            width: 20px;
            vertical-align: middle;
            margin-right: 5px;
        }
        .calculator {
            background: white;
            padding: 25px;
            border-radius: 8px;
            box-shadow: 0 2px 8px rgba(0,0,0,0.1);
        }
        .unit-tabs {
            display: flex;
            margin-bottom: 15px;
            border-bottom: 1px solid #ddd;
        }
        .unit-tab {
            padding: 8px 15px;
            cursor: pointer;
            border-bottom: 3px solid transparent;
        }
        .unit-tab.active {
            border-bottom: 3px solid #1e3a8a;
            font-weight: bold;
        }
        .input-group {
            margin-bottom: 20px;
        }
        label {
            display: block;
            margin-bottom: 8px;
            font-weight: 600;
        }
        input {
            width: 100%;
            padding: 10px;
            border: 1px solid #ddd;
            border-radius: 4px;
            font-size: 16px;
        }
        button {
            background-color: #1e3a8a;
            color: white;
            border: none;
            padding: 12px;
            border-radius: 4px;
            cursor: pointer;
            width: 100%;
            font-size: 16px;
            font-weight: bold;
            transition: background 0.3s;
        }
        button:hover {
            background-color: #1d4ed8;
        }
        #result {
            margin-top: 25px;
            padding: 20px;
            background: #eff6ff;
            border-left: 4px solid #1e3a8a;
            border-radius: 4px;
            display: none;
        }
        .brand-note {
            font-size: 14px;
            color: #4b5563;
            margin-top: 15px;
            padding: 10px;
            background: #f3f4f6;
            border-radius: 4px;
        }