style.css

.multiselect-container {
    display: none;
    position: absolute;
    background-color: #fff;
    color: #495057;
    font-family: 'helvetica neue', helvetica, arial;
    letter-spacing: .5px;
    font-weight: 200;
    min-width: 350px;
    width: 350px;
    box-shadow: 0 1px 3px 1px rgba(0,0,0,.2);
}

.multiselect-container.show {
    display: block;
}

.multiselect-container .multiselect-row-container {
    max-height: 200px;
    overflow: scroll;
}

.multiselect-container hr {
    height: 1px;
    border: 0;
    background-color: #ddd;
}

.multiselect-container .multiselect-row {
    padding: 10px;
    padding-top: 0;
}

.multiselect-container .multiselect-row:first-child {
    padding-top: 10px;
}

.multiselect-container .multiselect-row label {
    display: block;
    width: 100%;
}

.multiselect-container .multiselect-row label i {
    color: #ccc;
}

.multiselect-container .multiselect-row.multiselect-row-bottom {
    padding: 15px 10px; border-top: 1px #ddd solid;
}

.multiselect-button {
    font-weight:500;
    font-size: 0.8em;
    color: #228ae6;
    cursor: pointer;
    padding-top: 0.2em;
    border:0 ;
}

.multiselect-container .multiselect-row.multiselect-row-bottom .multiselect-button {
    float: right;
    margin-left: 10px;
    padding-top: 0.2em;
}

.multiselect-button.multiselect-save {
    background-color: #228ae6;
    color: #fff;
    padding: 0.6em;
    border-bottom: #0058A6 2px solid;
}

.multiselect-button.multiselect-save:active {
     background-color: #0058A6;
}

.multiselect-container .multiselect-row.multiselect-row-bottom .multiselect-button.multiselect-save {
    padding-top: 0.6em;
    margin-top: -5px;
}

.multiselect-container .multiselect-row input[type="checkbox"] {
    font-size: 1em;
}

.multiselect-container .multiselect-optgroup {
    font-weight: bold;
}

.multiselect-container .multiselect-option-in-optgroup {
    padding-left: 30px;
    padding-top:0;
}

.multiselect-container .multiselect-search {
    width: 96%;
    padding: 5px;
    border-radius: 5px;
    border: 1px solid #ddd;
}

.multiselect-container .multiselect-allselect, .multiselect-container .multiselect-searchresult-display {
    font-size: 0.8em;
    font-weight:500;
}

.multiselect-container .multiselect-allselect {
    cursor: pointer;
    color: #228ae6;
    font-weight:500;
}