.dropdown-container {
            position: relative;
            display: inline-block;
            /* allow clear button beside it */
            width: 100%;
        }
        .subject-filter {
            width: 100%;
        }

        .dropdown-button {
            border: 1px solid #ccc;
            cursor: pointer;
            background: #fff;
            border-radius: 4px;
            height: 30px;
            padding: 4px 8px;
            font-size: 13px;
            display: inline-block;
            /* important */
            min-width: 150px;
            /* optional: prevents button from being too small */
            white-space: nowrap;
            /* prevent text wrap */
        }

        .dropdown-content {
            display: none;
            position: absolute;
            top: 100%;
            left: 50%;
            transform: translateX(-50%);
            /*   center align */

            min-width: 365px;
            /*   increase width */
            max-width: 520px;
            /*   safe limit */
            width: auto;

            max-height: 360px;
            overflow-y: auto;

            background: #fff;
            border: 1px solid #ccc;
            z-index: 9999;
            padding: 8px;
            font-size: 13px;
        }

        .dropdown-container.open .dropdown-content {
            display: block;
        }

        .subject-group>label {
            cursor: pointer;
        }

        .child-list {
            margin-left: 20px;
        }

        .oa-type-filter {
            max-width: 180px;
        }

        .subject-group label {
            display: flex;
            gap: 6px;
            align-items: flex-start;
        }

        .subject-group b {
            white-space: normal;
            line-height: 1.3;
        }

        .clear-subjects {
            padding: 4px 8px;
            height: 30px;
            margin-left: 5px;
            /* small gap from dropdown */
            vertical-align: top;
        }

        .subject-filter-holder {
            display: inline-block;
            vertical-align: top;
        }