body {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

.navbar-brand {
    font-weight: bold;
    font-size: 1.5rem;
}

.card {
    border: none;
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.card-header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%) !important;
    border: none;
    padding: 1.5rem;
}

.nav-tabs {
    border-bottom: 2px solid #e9ecef;
}

.nav-tabs .nav-link {
    border: none;
    border-radius: 10px 10px 0 0;
    margin-right: 5px;
    padding: 12px 20px;
    font-weight: 500;
    color: #6c757d;
    transition: all 0.3s ease;
}

.nav-tabs .nav-link:hover {
    background-color: #f8f9fa;
    color: #495057;
}

.nav-tabs .nav-link.active {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
}

.btn {
    border-radius: 10px;
    padding: 10px 20px;
    font-weight: 500;
    transition: all 0.3s ease;
    border: none;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.btn-success {
    background: linear-gradient(135deg, #56ab2f 0%, #a8e6cf 100%);
}

.btn-info {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
}

.form-control {
    border-radius: 10px;
    border: 2px solid #e9ecef;
    padding: 12px 15px;
    transition: all 0.3s ease;
}

.form-control:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 0.2rem rgba(102, 126, 234, 0.25);
}

.placeholder-image,
.placeholder-text {
    padding: 40px;
    border: 2px dashed #dee2e6;
    border-radius: 10px;
    background-color: #f8f9fa;
    min-height: 200px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.result-image {
    max-width: 100%;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.result-text {
    background-color: #f8f9fa;
    border: 2px solid #e9ecef;
    border-radius: 10px;
    padding: 20px;
    font-family: 'Courier New', monospace;
    white-space: pre-wrap;
    word-break: break-all;
}

.alert {
    border-radius: 10px;
    border: none;
    padding: 15px 20px;
}

.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid #f3f3f3;
    border-top: 3px solid #667eea;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}

.tab-content {
    padding: 20px 0;
}

h5 {
    color: #495057;
    font-weight: 600;
    margin-bottom: 20px;
}

.form-label {
    font-weight: 500;
    color: #495057;
}

/* レスポンシブデザイン */
@media (max-width: 768px) {
    .container {
        padding: 10px;
    }

    .card-body {
        padding: 15px;
    }

    .nav-tabs .nav-link {
        padding: 8px 12px;
        font-size: 14px;
    }

    .btn {
        width: 100%;
        margin-bottom: 10px;
    }
}

/* ダークモード対応 */
@media (prefers-color-scheme: dark) {
    body {
        background: linear-gradient(135deg, #2c3e50 0%, #34495e 100%);
        color: #ecf0f1;
    }

    .card {
        background-color: #34495e;
        color: #ecf0f1;
    }

    .form-control {
        background-color: #2c3e50;
        border-color: #7f8c8d;
        color: #ecf0f1;
    }

    .form-control:focus {
        background-color: #2c3e50;
        color: #ecf0f1;
    }

    .placeholder-image,
    .placeholder-text {
        background-color: #2c3e50;
        border-color: #7f8c8d;
        color: #bdc3c7;
    }

    .result-text {
        background-color: #2c3e50;
        border-color: #7f8c8d;
        color: #ecf0f1;
    }
}