:root {
    --primary: #2c3e50;
    --secondary: #3498db;
    --accent: #e74c3c;
    --light: #ecf0f1;
    --dark: #34495e;
}

body {
    background-color: #f8f9fa;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

.navbar {
    background-color: var(--primary) !important;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.navbar-brand, .nav-link {
    color: white !important;
}

    .nav-link:hover {
        color: var(--secondary) !important;
    }

.card {
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
    transition: transform 0.3s ease;
    margin-bottom: 20px;
}

    .card:hover {
        transform: translateY(-5px);
        box-shadow: 0 6px 12px rgba(0,0,0,0.1);
    }

.card-header {
    background-color: var(--primary);
    color: white;
    border-radius: 8px 8px 0 0 !important;
}

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

    .btn-primary:hover {
        background-color: #2980b9;
        border-color: #2980b9;
    }

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

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

.table th {
    font-weight: 600;
}

.table-hover tbody tr:hover {
    background-color: rgba(52, 152, 219, 0.1);
}

.assignment-card {
    border-left: 4px solid var(--secondary);
}

.assignment-history {
    border-left: 4px solid #95a5a6;
}
@media (max-width: 768px) {
    .card {
        margin-bottom: 15px;
    }

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

    .btn-group .btn {
        padding: 0.25rem 0.5rem;
        font-size: 0.875rem;
    }
}
.main_logo {
    color:black;
}