problem with search button

Hi All

I am using the Taxonomy Picker Plugin and am having problem with the search button being slightly higher in some browsers then others. I have tried to sort this with css but with no luck. The link is here.
https://fundingforartists.org.uk/artists/

the css I am using is as follows`#sidebar-art .taxonomy-picker ul {
list-style: none;
margin: 0;
}
#sidebar-art .taxonomy-picker li {
float: left;
padding: 0 20px 0 0;
}

#sidebar-art .taxonomy-picker li label {
float: left;
padding: 0px 4px 0 0;
margin:0px 0 0 0;
}

#sidebar-art .taxonomy-picker p {
float: left;
padding: 0px 4px 0px 30px;
margin:0px 0 90px 0;
text-align: left;
display: block;
}`

can anyone see where I am going wrong?

Thanks for your time