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

:root {
    --primary-color: #2563eb;
    --secondary-color: #64748b;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --bg-color: #f8fafc;
    --surface-color: #ffffff;
    --text-color: #1e293b;
    --border-color: #e2e8f0;
    --shadow: 0 1px 3px rgba(0,0,0,0.1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}

header {
    background: var(--surface-color);
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.top-nav {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    padding: 0 1rem;
}

.nav-brand {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--primary-color);
    padding: 1rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    flex: 1;
    gap: 0.5rem;
}

.nav-menu a {
    display: block;
    padding: 1rem 0.75rem;
    color: var(--text-color);
    text-decoration: none;
    border-bottom: 2px solid transparent;
    transition: all 0.2s;
}

.nav-menu a:hover, .nav-menu a.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

main {
    max-width: 1400px;
    margin: 2rem auto;
    padding: 0 1rem;
    min-height: calc(100vh - 200px);
}

footer {
    text-align: center;
    padding: 2rem;
    color: var(--secondary-color);
    background: var(--surface-color);
    border-top: 1px solid var(--border-color);
    margin-top: 4rem;
}

.card {
    background: var(--surface-color);
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.card-header {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--border-color);
}

.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.25rem;
    font-weight: 500;
    font-size: 0.875rem;
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 0.875rem;
}

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

.form-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
}

.btn {
    padding: 0.5rem 1rem;
    border: none;
    border-radius: 4px;
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
    display: inline-block;
}

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

.btn-primary:hover {
    background: #1d4ed8;
}

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

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

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

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

.btn-group {
    display: flex;
    gap: 0.5rem;
    margin-top: 1rem;
}

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

table thead {
    background: var(--bg-color);
    position: sticky;
    top: 0;
}

table th,
table td {
    padding: 0.75rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

table th {
    font-weight: 600;
    color: var(--secondary-color);
}

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

.alert {
    padding: 1rem;
    border-radius: 4px;
    margin-bottom: 1rem;
}

.alert-success {
    background: #d1fae5;
    color: #065f46;
    border: 1px solid #10b981;
}

.alert-danger {
    background: #fee2e2;
    color: #991b1b;
    border: 1px solid #ef4444;
}

.alert-warning {
    background: #fef3c7;
    color: #92400e;
    border: 1px solid #f59e0b;
}

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

.collapsible {
    margin-top: 1rem;
}

.collapsible-header {
    cursor: pointer;
    padding: 0.75rem;
    background: var(--bg-color);
    border-radius: 4px;
    font-weight: 500;
    user-select: none;
}

.collapsible-header:hover {
    background: var(--border-color);
}

.collapsible-content {
    display: none;
    padding: 1rem 0;
}

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

.badge {
    display: inline-block;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 600;
}

.badge-success {
    background: var(--success-color);
    color: white;
}

.badge-danger {
    background: var(--danger-color);
    color: white;
}

.badge-warning {
    background: var(--warning-color);
    color: white;
}

.table-actions {
    display: flex;
    gap: 0.5rem;
}

.table-actions button {
    padding: 0.25rem 0.5rem;
    font-size: 0.75rem;
}

.text-right {
    text-align: right;
}

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

.row-total {
    font-weight: 600;
    background: #f1f5f9 !important;
}

.row-grand-total {
    font-weight: 700;
    background: #e2e8f0 !important;
    border-top: 2px solid var(--primary-color);
}