invoice/static/css/style.css

    /* Styling for the navigation tabs */
    .nav-tabs {
        border-bottom: 2px solid #ddd;
        background-color: #f9f9f9;
        border-radius: 5px;
    }

    .nav-tabs .nav-item {
        margin-bottom: -1px;
    }

    .nav-tabs .nav-link {
        color: #007bff; /* Blue color for tabs */
        border: 1px solid transparent;
        border-top-left-radius: 5px;
        border-top-right-radius: 5px;
        padding: 10px 15px;
        transition: background-color 0.3s, border-color 0.3s;
    }

    .nav-tabs .nav-link:hover {
        background-color: #e9ecef;
        border-color: #ddd #ddd #f9f9f9;
    }

    .nav-tabs .nav-link.active {
        background-color: #fff;
        border-color: #ddd #ddd transparent;
        color: #495057;
        font-weight: bold;
    }

    /* Extra padding for the tab content to make it more spacious */
    .tab-content {
        padding: 15px;
        border: 1px solid #ddd;
        border-top: none;
        background-color: #fff;
        border-bottom-left-radius: 5px;
        border-bottom-right-radius: 5px;
    }

    /* Optional: custom colors for the active tab */
    .nav-tabs .nav-link.active {
        background-color: #4CAF50; /* Green background for the active tab */
        color: white; /* White text for the active tab */
        border-color: #4CAF50;
    }

    /* Customize tab text hover color */
    .nav-tabs .nav-link:hover {
        color: #0056b3;
    }