Changing the Form Width

To change the form width, navigate to Form design and edit the form width there.

Also, you may want to use the "Code" element and paste the following snippet in it:

<style>
.wrap-form {
    width: 820px !important;
}
div#workspace {
    max-width: 820px !important;
    width: 820px !important;
}
</style>

It’s possible to set up the width not only in px but also in % 😌

max-width: 100% !important;
width: 100% !important;