body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f8f9fa;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    flex: 1;
}

.card {
    border: none;
    border-radius: 10px;
}

.btn-primary {
    background-color: #0d6efd;
    border: none;
    padding: 12px;
    font-weight: 600;
    transition: all 0.3s;
}

.btn-primary:hover {
    background-color: #0b5ed7;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(13, 110, 253, 0.3);
}

.security-info {
    border-left: 4px solid #28a745;
}

footer {
    margin-top: auto;
}

.alert {
    border-radius: 8px;
}

.accordion-button:not(.collapsed) {
    background-color: #e7f3ff;
    color: #0d6efd;
}

.premium-locked .accordion-button {
    background-color: #fff3cd;
    cursor: not-allowed;
    opacity: 0.7;
}

.premium-locked .accordion-button:hover {
    background-color: #fff3cd;
}

/* ウォーターマーク配置グリッド */
.watermark-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
    margin-bottom: 1rem;
}

.watermark-option {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 15px;
    border: 2px solid #dee2e6;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s;
}

.watermark-option:hover {
    border-color: #0d6efd;
    background-color: #f8f9fa;
}

.watermark-option input[type="radio"] {
    display: none;
}

.watermark-option input[type="radio"]:checked + span {
    color: #0d6efd;
    font-weight: bold;
}

.watermark-option input[type="radio"]:checked ~ * {
    border-color: #0d6efd;
}

.watermark-option span {
    margin-top: 5px;
    font-size: 14px;
}

/* スマホ対応 */
@media (max-width: 768px) {
    .watermark-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 5px;
    }
    
    .watermark-option {
        padding: 10px;
        font-size: 12px;
    }
}