.sdm-amount-options {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}
.sdm-amount-box {
    border: 2px solid #ccc;
    border-radius: 8px;
    padding: 15px 25px;
    text-align: center;
    cursor: pointer;
    background: #fff;
    transition: 0.2s ease-in-out;
    min-width: 120px;
}
.sdm-amount-box:hover { border-color: #0073aa; }
.sdm-amount-box input[type="radio"] { display: none; }
.sdm-amount-box input[type="radio"]:checked + .sdm-amount-label {
    color: #fff; background-color: #0073aa; border-radius: 6px; padding: 5px 10px;
}
.sdm-amount-label {
    display: block; font-weight: bold; margin-bottom: 5px; color: #333;
}
.sdm-desc {
    display: block; font-size: 13px; color: #666;
}