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

:root {
    --primary-color: #2563eb;
    --secondary-color: #64748b;
    --success-color: #10b981;
    --error-color: #ef4444;
    --border-color: #e2e8f0;
    --background-color: #f8fafc;
    --text-color: #1e293b;
    --card-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

header {
    text-align: center;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.subtitle {
    color: var(--secondary-color);
    font-size: 1.1rem;
}

.tabs {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    border-bottom: 2px solid var(--border-color);
}

.tab-button {
    padding: 0.75rem 1.5rem;
    border: none;
    background: none;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    color: var(--secondary-color);
    transition: all 0.3s ease;
    border-bottom: 3px solid transparent;
    margin-bottom: -2px;
}

.tab-button:hover {
    color: var(--primary-color);
}

.tab-button.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

.tab-content {
    display: none;
}

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

.card {
    background: white;
    padding: 2rem;
    border-radius: 0.5rem;
    box-shadow: var(--card-shadow);
    margin-bottom: 1.5rem;
}

.card h2 {
    color: var(--text-color);
    margin-bottom: 1.5rem;
    font-size: 1.5rem;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-color);
}

.form-group input {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 0.375rem;
    font-size: 1rem;
    transition: border-color 0.3s ease;
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.term-inputs {
    display: flex;
    gap: 1rem;
}

.term-inputs > div {
    flex: 1;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.term-inputs input {
    width: 100%;
}

.term-inputs span {
    color: var(--secondary-color);
    white-space: nowrap;
}

.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 0.375rem;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
    width: 100%;
}

.btn-primary:hover {
    background-color: #1d4ed8;
    transform: translateY(-2px);
    box-shadow: 0 4px 6px rgba(37, 99, 235, 0.3);
}

.btn-secondary {
    background-color: var(--secondary-color);
    color: white;
}

.btn-secondary:hover {
    background-color: #475569;
}

.btn-danger {
    background-color: var(--error-color);
    color: white;
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

.btn-danger:hover {
    background-color: #dc2626;
}

.loading {
    text-align: center;
    padding: 2rem;
}

.spinner {
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    width: 50px;
    height: 50px;
    animation: spin 1s linear infinite;
    margin: 0 auto 1rem;
}

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

.error-message {
    background-color: #fee2e2;
    color: #991b1b;
    padding: 1rem;
    border-radius: 0.375rem;
    margin-bottom: 1.5rem;
    border-left: 4px solid var(--error-color);
}

.summary {
    background-color: var(--background-color);
    padding: 1rem;
    border-radius: 0.375rem;
    margin-bottom: 1.5rem;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
}

.summary-item {
    text-align: center;
}

.summary-item label {
    display: block;
    font-size: 0.875rem;
    color: var(--secondary-color);
    margin-bottom: 0.25rem;
}

.summary-item .value {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-color);
}

.table-container {
    overflow-x: auto;
}

table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.875rem;
}

thead th {
    background-color: var(--background-color);
    padding: 0.75rem;
    text-align: right;
    font-weight: 600;
    color: var(--text-color);
    border-bottom: 2px solid var(--border-color);
}

thead th:first-child,
thead th:nth-child(2) {
    text-align: left;
}

tbody td {
    padding: 0.75rem;
    border-bottom: 1px solid var(--border-color);
    text-align: right;
}

tbody td:first-child,
tbody td:nth-child(2) {
    text-align: left;
}

tbody tr:hover {
    background-color: var(--background-color);
}

.history-item {
    border: 1px solid var(--border-color);
    border-radius: 0.375rem;
    padding: 1rem;
    margin-bottom: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.history-item:hover {
    border-color: var(--primary-color);
    box-shadow: var(--card-shadow);
}

.history-item-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
}

.history-item-header h3 {
    color: var(--primary-color);
    font-size: 1.1rem;
}

.history-item-info {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 0.75rem;
    color: var(--secondary-color);
    font-size: 0.875rem;
}

.history-item-info div {
    display: flex;
    flex-direction: column;
}

.history-item-info label {
    font-weight: 500;
    color: var(--text-color);
}

.history-actions {
    display: flex;
    gap: 0.5rem;
    margin-top: 1rem;
}

.empty-state {
    text-align: center;
    padding: 3rem;
    color: var(--secondary-color);
}

.empty-state-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }

    header h1 {
        font-size: 1.75rem;
    }

    .card {
        padding: 1rem;
    }

    table {
        font-size: 0.75rem;
    }

    thead th,
    tbody td {
        padding: 0.5rem;
    }
}