wagtail/client/scss/elements/_forms.scss

@use 'sass:map';
// Legacy form reset styles. Avoid adding any new styles here.
form {
  // Historically, Wagtail forms rendered all fields as list items.
  // This is still the case in some instances, and there may be a lot of
  // of form widgets relying on this too.
  ul,
  li {
    list-style-type: none;
  }

  ul {
    margin: 0;
    padding: 0;
  }
}

fieldset {
  border: 0;
  padding: 0 0 2em;
  margin: 0;
}

// Special styles to counteract Firefox's completely unwarranted assumptions about button styles
input[type='submit'],
input[type='reset'],
input[type='button'],
button {
  padding: 0 1em;

  @include media-breakpoint-up(sm) {
    &.button-small {
      height: 2em;
    }
  }
}