how to resize the text area?

can anyone help me to resize the height of the <your message> area? It tooks too much space because it’s height. but i cannot figure out how to make it smaller, my form code is as below:

<div class="leo-form">
<div class="one-half">[text* your-name placeholder "Your Name*"] </div>
<div class="one-half last">[email* your-email placeholder "Your Email*"] </div>
<div>[textarea your-message placeholder "Your Message"] </div>
<div>[submit "Submit"]</div>
</div>

<style>
.leo-form div{margin-bottom:20px;}
.one-half,.one-third {
    position: relative;
    margin-right: 4%;
    float: left;
    z-index: 99;
}
.one-half { width: 48%; }
.one-third { width: 30.66%; }
.last {
    margin-right: 0 !important;
    clear: right;
}
@media only screen and (max-width: 767px) {
    .one-half, .one-third {
        width: 100%;
        margin-right: 0;
    }
}
</style>

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