This should start you on your way:
.searchandfilter[data-sf-form-id="971"] li.sf-field-search input {
padding: 1.5px 10px;
}
.searchandfilter[data-sf-form-id="971"] > ul > li,
.searchandfilter[data-sf-form-id="971"] li.sf-field-search input,
.searchandfilter[data-sf-form-id="971"] li.sf-field-search label,
.searchandfilter[data-sf-form-id="971"] .select2-container {
min-width: 245px;
float: left;
}
.searchandfilter[data-sf-form-id="971"] > ul {
display: table;
}
.searchandfilter[data-sf-form-id="971"] li.sf-field-submit {
clear: both;
}
Note that you have some CSS you already made:
input.sf-input-text {
background-color: white;
border: 1px solid #aaa !important;
margin-top: 3px;
font-size: 14px;
}
The font-size and margin-top in that block may need to be removed. It may also be that you need to place the CSS in a media query to apply only to desktop, but this should get you started. This is really outside the scope of our normal support, so if you need more doing, you may need to hire a third party coder to help you.