I tried the above solutions with no luck but was able to succesfully get a one line email address/submit button with no left margin etc.. (forms 2.0, simple theme).
/* Add your custom CSS below */
/* remove width constraint to allow for float */
.mktoForm {
width: auto !important
}
/* remove left margin */
.mktoForm span {
margin-left: 0px !important;
}
/* align row */
.mktoFormRow {
float: left !important;
}
/* remove bottom margin */
.mktoFormCol {
margin-bottom: 0px !important;
}
/* remove offset */
.mktoOffset {
width: auto !important;
}
/* remove gutter margin */
.mktoGutter {
width: 0px !important;
}
/* button style */
.mktoButton {
height: 31px !important;
width: 45px !important;
}
.mktoForm input[type=email] {
height:31px !important;
width:171px !important;
}