slick.headerbuttons.css

.slick-column-name,
.slick-sort-indicator {
    /**
     * This makes all "float:right" elements after it that spill over to the next line
     * display way below the lower boundary of the column thus hiding them.
     */
    display: inline-block;
    float: left;
    margin-bottom: 100px;
}

.slick-header-button {
    display: inline-block;
    float: right;
    vertical-align: top;
    margin: 1px;
    /**
    * This makes all "float:right" elements after it that spill over to the next line
    * display way below the lower boundary of the column thus hiding them.
    */
    margin-bottom: 100px;
    height: 15px;
    width: 15px;
    background-repeat: no-repeat;
    background-position: center center;
    cursor: pointer;
}

.slick-header-button-hidden {
    width: 0;

    -webkit-transition: 0.2s width;
    -ms-transition: 0.2s width;
    transition: 0.2s width;
}

.slick-header-column:hover > .slick-header-button {
    width: 15px;
}