Form Button Styling Font and Font Size

I'm hoping someone can help me change the size of the font in an embedded Marketo form. I can't figure out the specific syntax to grab the button and style it.  The form exists on this page: https://www.insurate.com/agent-qs

I'd like to increase the size of the font, increase the size of the button and remove the line around the button. I've included the code below. Aside from the challenge here, I'm just at such a loss as to why this is so impossible to do. Thanks to anyone who can help!

/* Add your custom CSS below */
.mktoForm .mktoRequiredField label.mktoLabel {
font-weight:normal !important;
}
.mktoForm .mktoOffset {
float: left;
height: .5em;
width:10px;
}

.mktoForm .mktoButton {
margin-top: 20px !important;
padding: 15px !important;
background:#fab300 !important;
width: 250px !important;
border: 1px solid #fab300 !important;
font-size: 16 !important;
color: #000000 !important;
}
.mktoform .mktoButtonRow {
width: 100% !important;
text-align: center!important;
}
.mktoForm .mktoCheckboxList {
font-weight:normal !important;
}