* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    background: white;
    border-radius: 15px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 30px;
    text-align: center;
}

header h1 {
    font-size: 2em;
    font-weight: 600;
}

.tabs {
    display: flex;
    background: #f5f5f5;
    border-bottom: 2px solid #e0e0e0;
}

.tab-btn {
    flex: 1;
    padding: 15px 20px;
    background: transparent;
    border: none;
    cursor: pointer;
    font-size: 16px;
    font-weight: 500;
    color: #666;
    transition: all 0.3s;
    border-bottom: 3px solid transparent;
}

.tab-btn:hover {
    background: #e8e8e8;
    color: #333;
}

.tab-btn.active {
    color: #667eea;
    border-bottom-color: #667eea;
    background: white;
}

.tab-content {
    display: none;
    padding: 30px;
    animation: fadeIn 0.3s;
}

.tab-content.active {
    display: block;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.card {
    background: #fafafa;
    border-radius: 10px;
    padding: 25px;
    margin-bottom: 20px;
}

.card h2 {
    color: #333;
    margin-bottom: 20px;
    font-size: 1.5em;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    color: #555;
    font-weight: 500;
}

.form-group input {
    width: 100%;
    padding: 12px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 16px;
    transition: border-color 0.3s;
}

.form-group input:focus {
    outline: none;
    border-color: #667eea;
}

.form-group small {
    display: block;
    margin-top: 5px;
    color: #888;
    font-size: 0.9em;
}

.btn {
    padding: 12px 30px;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.btn-primary {
    background: #667eea;
    color: white;
}

.btn-primary:hover {
    background: #5568d3;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.btn-success {
    background: #28a745;
    color: white;
}

.btn-success:hover {
    background: #218838;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(40, 167, 69, 0.4);
}

.btn-info {
    background: #17a2b8;
    color: white;
}

.btn-info:hover {
    background: #138496;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(23, 162, 184, 0.4);
}

.btn-secondary {
    background: #6c757d;
    color: white;
    margin-bottom: 20px;
}

.btn-secondary:hover {
    background: #5a6268;
}

.result {
    margin-top: 20px;
    padding: 15px;
    border-radius: 8px;
    display: none;
}

.result.success {
    display: block;
    background: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.result.error {
    display: block;
    background: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.result.info {
    display: block;
    background: #d1ecf1;
    color: #0c5460;
    border: 1px solid #bee5eb;
}

.cards-list {
    margin-top: 20px;
}

.card-item {
    background: white;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 15px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: all 0.3s;
}

.card-item:hover {
    border-color: #667eea;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.card-info {
    flex: 1;
}

.card-info h3 {
    color: #333;
    margin-bottom: 5px;
    font-size: 1.2em;
}

.card-info p {
    color: #666;
    margin: 5px 0;
}

.balance {
    font-size: 1.5em;
    font-weight: 600;
    color: #28a745;
}

.transaction-history {
    margin-top: 30px;
}

.transaction-item {
    background: white;
    border-left: 4px solid #667eea;
    padding: 15px;
    margin-bottom: 10px;
    border-radius: 5px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.transaction-item.deduct {
    border-left-color: #dc3545;
}

.transaction-item.add {
    border-left-color: #28a745;
}

.transaction-info {
    flex: 1;
}

.transaction-amount {
    font-size: 1.2em;
    font-weight: 600;
}

.transaction-amount.positive {
    color: #28a745;
}

.transaction-amount.negative {
    color: #dc3545;
}

.loading {
    text-align: center;
    padding: 20px;
    color: #666;
}

.empty-state {
    text-align: center;
    padding: 40px;
    color: #999;
}

.empty-state::before {
    content: "📭";
    font-size: 3em;
    display: block;
    margin-bottom: 10px;
}

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

    .tab-btn {
        border-bottom: 1px solid #e0e0e0;
        border-right: none;
    }

    .tab-btn.active {
        border-bottom-color: #e0e0e0;
        border-left: 3px solid #667eea;
    }

    .card-item {
        flex-direction: column;
        align-items: flex-start;
    }

    .balance {
        margin-top: 10px;
    }
}