style.css

body {
    background-color: #f8f9fa;
}

.navbar {
    margin-bottom: 20px;
}

.card {
    border: none;
    border-radius: 5px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.card-header {
    border-bottom: none;
}

.card-title {
    font-size: 18px;
    font-weight: bold;
}

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

.table th {
    font-weight: bold;
}

.table td {
    vertical-align: middle;
}

@media (max-width: 576px) {
    .table {
        font-size: 14px;
    }
}

.invalid-feedback {
    display: none;
    color: red;
    font-size: 14px;
    margin-top: 5px;
}

.is-invalid {
    border-color: red;
}

.is-invalid+.invalid-feedback {
    display: block;
}

.filter-container {
    margin-bottom: 20px;
}

.filter-container select,
.filter-container input {
    margin-right: 10px;
}

.due-payment {
    color: red;
}

.paid-payment {
    color: green;
}