pub trait HasCssRules {
// Required methods
fn css_rules(&self) -> &CssRules;
fn css_rules_mut(&mut self) -> &mut CssRules;
fn css_rules_slice(&self) -> &[CssRule];
fn css_rules_vec(&self) -> &Vec<CssRule>;
fn css_rules_vec_mut(&mut self) -> &mut Vec<CssRule>;
}