body {
    background: #f4f6f9;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

.navbar-brand {
    font-weight: 700;
    font-size: 1.3rem;
}

.sidebar {
    min-height: calc(100vh - 60px);
}

.card {
    border: none;
    border-radius: 10px;
    box-shadow: 0 2px 6px rgba(0,0,0,0.08);
    transition: transform 0.2s;
}

.card:hover {
    transform: translateY(-2px);
}

.card-header {
    background: #fff;
    border-bottom: 2px solid #f0f0f0;
    font-weight: 600;
    border-radius: 10px 10px 0 0 !important;
}

.stat-card {
    border-left: 4px solid;
}

.stat-card.income { border-left-color: #28a745; }
.stat-card.expense { border-left-color: #dc3545; }
.stat-card.students { border-left-color: #007bff; }
.stat-card.courses { border-left-color: #ffc107; }
.stat-card.pending { border-left-color: #e74a3b; }

.stat-value {
    font-size: 1.8rem;
    font-weight: 700;
}

.btn {
    border-radius: 6px;
    padding: 6px 16px;
    font-weight: 500;
}

.form-control, .form-select {
    border-radius: 6px;
    border: 1px solid #dde1e6;
    padding: 8px 12px;
}

.form-control:focus, .form-select:focus {
    border-color: #0d6efd;
    box-shadow: 0 0 0 0.2rem rgba(13,110,253,0.15);
}

.table {
    font-size: 0.95rem;
}

.table thead th {
    background: #f8f9fa;
    font-weight: 600;
    border-bottom: 2px solid #dee2e6;
}

.badge {
    font-weight: 500;
    padding: 5px 10px;
}

.receipt-box {
    background: #fff;
    border: 2px dashed #ddd;
    padding: 30px;
    max-width: 600px;
    margin: 0 auto;
}

.receipt-header {
    text-align: center;
    border-bottom: 2px solid #333;
    padding-bottom: 15px;
    margin-bottom: 20px;
}

.receipt-logo {
    max-width: 150px;
    max-height: 60px;
    width: auto;
    height: auto;
    margin-bottom: 10px;
}

.receipt-contact {
    font-size: 0.85rem;
    color: #555;
}

.receipt-title {
    font-size: 1.5rem;
    font-weight: 700;
}

@media print {
    .navbar, .btn, .no-print { display: none !important; }
    .card { box-shadow: none; border: 1px solid #ddd; }
}

.page-title {
    color: #333;
    font-weight: 600;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 3px solid #0d6efd;
}

.dataTables_wrapper .dataTables_filter input {
    border: 1px solid #ddd;
    border-radius: 4px;
    padding: 4px 8px;
}

.dropdown-submenu {
    position: relative;
}

.dropdown-submenu > .dropdown-menu {
    top: 0;
    left: 100%;
    margin-top: -6px;
    display: none;
}

.dropdown-submenu:hover > .dropdown-menu,
.dropdown-submenu > .dropdown-menu.show {
    display: block;
}

.dropdown-submenu > a.dropdown-toggle::after {
    float: right;
    margin-top: 8px;
    border-top: 0.3em solid transparent;
    border-right: 0;
    border-bottom: 0.3em solid transparent;
    border-left: 0.3em solid;
    vertical-align: middle;
}