By default, the form element embeds styles for your forms onto the rendered HTML page.  This can make it difficult to override those styles if you desire to create custom styles for your forms.

But, there is an easy fix.

Once you have added a form element to a page, simply hover over the edit button for the element and select "settings."  Then, uncheck the box that says "include basic form styles" and update.  This will remove all default styles for the form element and you will be free to style your form however you wish.

HINT:  You might want to copy the default form styles which are rendered on the page over to your custom stylesheets before you disable the form styles.  By doing this, you will have a starting place for the form styles and can simply tweak and change as needed.