* { margin: 0; padding: 0; box-sizing: border-box; }
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: #f0f2f5;
}
.sidebar {
    width: 260px;
    background-color: #f3f4f6;
    border-right: 1px solid #e5e7eb;
    position: fixed;
    top: 0;
    left: 0;
    height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}
.sidebar-header {
    padding: 24px 20px;
    font-weight: 600;
    font-size: 18px;
    border-bottom: 1px solid #e5e7eb;
    background-color: #ffffff;
}
.nav a {
    display: block;
    padding: 10px 20px;
    color: #374151;
    text-decoration: none;
    margin: 4px 12px;
    border-radius: 8px;
}
.nav a.active, .nav a:hover {
    background-color: #e0e7ff;
    color: #1e40af;
}
.sidebar-footer {
    padding: 20px;
    border-top: 1px solid #e5e7eb;
}
.main {
    margin-left: 260px;
    padding: 24px 32px;
    background: #ffffff;
    min-height: 100vh;
}
.page-title {
    font-size: 24px;
    font-weight: 600;
    margin-bottom: 24px;
    padding-bottom: 12px;
    border-bottom: 1px solid #e5e7eb;
}
.card {
    background: #ffffff;
    border-radius: 12px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    padding: 20px;
    margin-bottom: 20px;
}
button, .button {
    background-color: #3b82f6;
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
}
button.danger {
    background-color: #ef4444;
}
input, textarea, select {
    width: 100%;
    padding: 8px 12px;
    border: 1px solid #d1d5db;
    border-radius: 6px;
    font-size: 14px;
}
.form-group {
    margin-bottom: 16px;
}
label {
    display: block;
    font-weight: 500;
    margin-bottom: 6px;
}
table {
    width: 100%;
    border-collapse: collapse;
}
th, td {
    text-align: left;
    padding: 12px;
    border-bottom: 1px solid #e5e7eb;
}
.text-center {
    text-align: center;
}