All of that is determined by your theme, or you child theme’s, CSS. My plugin has a bare minimum of CSS styling applied, because I adhere to the best practice of letting the theme control the appearance, while plugins should only add functionality.
The sign-up form has no styling applied to it at all. It is a standard form, with each field/input wrapped in paragraph tags that don’t have a style or class assigned to them. Within the paragraph tags for each field there is the name of the field, which is wrapped in label tags, and the actual input fields, which are standard text input fields. NO CSS or inline styles have been applied!
That means, any weird formatting is due to how your own theme or child them applies styles to paragraphs, labels, and text inputs within a form.
The lists of sign-up sheets and tasks are done with tables, and there is very minimal styling applied to them.
To make them work better with your theme, you’re going to have to override how your theme handles those files with some custom CSS. You can use the “inspect element” feature of your browser to find names and/or ids of various elements my plugin generates if you want to target them specifically. The signup form has a name field, so you can target paragraphs, labels, and text inputs inside of that specific form if you need to alter only the way those are displayed.
As far as responsiveness goes, that is also up to your theme. Since I’m not doing any type of complex CSS styling, it’s all up to your theme to decide what gets moved to new lines and how tables respond on smaller screens. You may need to create some custom CSS rules to target those table elements when on smaller screens to make them fit better on mobile phones.
I don’t design themes, since graphics and CSS are not my strong suits, which is why I try to keep styling to a minimum in all my plugins.
