body {
            background: #020617;
            color: #f9fafb;
        }
        .calculator-shell {
            max-width: 960px;
            margin: 40px auto;
        }
        .card-calculator {
            border-radius: 20px;
            border: none;
            overflow: hidden;
        }
        .card-calculator .card-header {
            background: radial-gradient(circle at top left, #22c55e, #0f172a);
            color: #ecfeff;
        }
        .mode-toggle .btn {
            border-radius: 999px !important;
        }
        .output-box {
            background: #020617;
            border-radius: 16px;
            padding: 16px;
            margin-bottom: 12px;
            color:#fff;
        }
        .output-box h5 {
            margin-bottom: 0.25rem;
        }
        .output-value {
            font-size: 1.3rem;
            font-weight: 700;
        }
        label {
            font-weight: 500;
        }
        .advanced-toggle {
            cursor: pointer;
        }