How to set the height for the Hero Widget

hi
i am building a website with a parallax site and I am using a hero widget and i like to change the widget size without using the buttons. the customm css does help the following code doesnt work.
.custom-hero-one .sow-slider-image-container {
height: 300px;

}

i loose the h3 text if i modify the widget with this
.sow-slider-base ul.sow-slider-images li.sow-slider-image .sow-slider-image-container .sow-slider-image-wrapper > *:last-child {
margin-left: 0em;
width: -2px;
font-size: 0px;
line-height: -1px;
font-style: normal;
position: relative;
height:200px
}