:root {
    --primary: #3498db;
    --primary-dark: #2c3e50;
    --secondary: #f8f9fa;
    --success: #2ecc71;
    --warning: #f39c12;
    --danger: #e74c3c;
}

body {
    background: linear-gradient(135deg, #f5f7fa 0%, #e4edf5 100%);
    min-height: 100vh;
    /*padding-top: 2rem;*/
    /*padding-bottom: 2rem;*/
    /*font-family: 'Segoe UI', 'Microsoft YaHei', sans-serif;*/
}

.app-container {
    max-width: 800px;
    margin: 0 auto;
}

.card {
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
    border: none;
    overflow: hidden;
    transition: transform 0.3s ease;
    margin-bottom: 2rem;
}

.card:hover {
    /*transform: translateY(-5px);*/
}

.card-header {
    background: linear-gradient(90deg, var(--primary), var(--primary-dark));
    color: white;
    font-weight: 600;
    font-size: 1.6rem;
    padding: 1.3rem;
    border-radius: 15px 15px 0 0 !important;
    position: relative;
}

.card-header::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, var(--warning), var(--danger));
}

.logo {
    font-size: 2rem;
    margin-right: 10px;
    color: #ffeb3b;
}

.input-section {
    background: linear-gradient(135deg, #ffffff 0%, #f8f9fa 100%);
    padding: 1.5rem;
    border-radius: 10px;
    margin-bottom: 1.5rem;
}

.result-container {
    background: linear-gradient(135deg, #e3f2fd 0%, #bbdefb 100%);
    border-radius: 10px;
    padding: 1.8rem;
    min-height: 120px;
    border: 2px dashed #3498db;
    transition: all 0.3s ease;
    margin-bottom: 1.5rem;
    position: relative;
}

.result-text {
    font-size: 1.4rem;
    font-weight: 600;
    color: var(--primary-dark);
    margin: 0;
    line-height: 1.6;
    text-align: center;
    padding: 1rem;
}

.btn-group {
    display: flex;
    gap: 12px;
    justify-content: center;
    margin-top: 1.5rem;
}

.btn {
    padding: 0.8rem 1.8rem;
    font-weight: 600;
    border-radius: 8px;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    border: none;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.btn i {
    font-size: 1.2rem;
}

.btn-primary {
    background: linear-gradient(90deg, var(--primary), var(--primary-dark));
    color: white;
}

.btn-primary:hover {
    background: linear-gradient(90deg, var(--primary-dark), var(--primary));
    transform: translateY(-3px);
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
}

.btn-success {
    background: linear-gradient(90deg, var(--success), #27ae60);
    color: white;
}

.btn-success:hover {
    background: linear-gradient(90deg, #27ae60, var(--success));
    transform: translateY(-3px);
}

.btn-warning {
    background: linear-gradient(90deg, var(--warning), #e67e22);
    color: white;
}

.btn-warning:hover {
    background: linear-gradient(90deg, #e67e22, var(--warning));
    transform: translateY(-3px);
}

.btn-danger {
    background: linear-gradient(90deg, var(--danger), #c0392b);
    color: white;
}

.btn-danger:hover {
    background: linear-gradient(90deg, #c0392b, var(--danger));
    transform: translateY(-3px);
}

.examples {
    background: linear-gradient(135deg, #e3f2fd 0%, #bbdefb 100%);
    border-radius: 10px;
    padding: 1.5rem;
    margin-top: 1.5rem;
}

.examples h5 {
    color: var(--primary-dark);
    border-bottom: 2px solid var(--primary);
    padding-bottom: 0.8rem;
    margin-bottom: 1.2rem;
    display: flex;
    align-items: center;
    gap: 10px;
}

.example-item {
    padding: 0.8rem 1rem;
    border-bottom: 1px dashed #90caf9;
    display: flex;
    justify-content: space-between;
    transition: background-color 0.3s ease;
}

.example-item:hover {
    background-color: rgba(144, 202, 249, 0.2);
    border-radius: 6px;
}

.example-item:last-child {
    border-bottom: none;
}

.example-num {
    font-weight: bold;
    color: var(--primary-dark);
}

.example-result {
    font-weight: 500;
    color: #e74c3c;
}

.footer {
    color: #7f8c8d;
    font-size: 0.95rem;
    text-align: center;
    margin-top: 2rem;
    padding: 1rem;
}

.notification {
    position: fixed;
    top: 48%;
    right: 45%;
    padding: 15px 25px;
    border-radius: 8px;
    color: white;
    font-weight: 500;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
    z-index: 1000;
    opacity: 0;
    transform: translateX(100px);
    transition: all 0.4s ease;
}

.notification.show {
    opacity: 1;
    transform: translateX(0);
}

.notification.success {
    background: linear-gradient(90deg, var(--success), #27ae60);
}

.notification.error {
    background: linear-gradient(90deg, var(--danger), #c0392b);
}

.limit-note {
    font-size: 0.9rem;
    color: #7f8c8d;
    margin-top: 0.8rem;
    text-align: center;
}

.input-group-text {
    background: linear-gradient(90deg, #e3f2fd, #bbdefb);
    font-weight: 500;
    min-width: 50px;
    justify-content: center;
}

@media (max-width: 768px) {
    .btn-group {
        flex-direction: column;
    }

    .result-text {
        font-size: 1.2rem;
    }
}