When I click one of the "Click me", "Submit", "Preset" buttons in Components/Button section, entire page jumps with 1 pixel. Looks bad. Checkbox labels text is

When I click one of the "Click me", "Submit", "Preset" buttons in Components/Button section, entire page jumps with 1 pixel. Looks bad. Checkbox labels text is selectable. Should not happen in UI. Same about title bars. Title bars also do not set cursor: pointer. Also happens in some other components. Dropdown contents have wrong colors. I think they use default browser styling or something like that. Those are minor nitpicks, of course. This style is very nostalgic, thanks for making it. I thought about using this kind of UI for some web app, I think I'll reimplement it myself (because that's the fun), but I'll keep this style in mind.