CSS Selector
A CSS selector is a pattern that finds elements on a page so styles can be applied to them.
Another example
A design system selects `[data-state='open']` on a disclosure instead of `.blue-chevron`. A visual redesign does not break it. Where supported, `:has(> input:invalid)` styles a field group with an invalid input. Error text from the server remains the working fallback.
Main parts
- 01Compound selectors
- 02Combinators
- 03Matched subject
Use it when
Choose stable hooks that describe meaning. Keep specificity as low as useful and avoid depending on an exact DOM depth.
Do not use it when
Avoid selectors named after appearance, generated markup, or long child chains. They make later changes risky.
Name used in code
type, class, ID, attribute, combinator, pseudo-class, and pseudo-element selectors Before you ship
Check content order, shared design values, component consistency, contrast, zoom, and layout changes by screen size. Verify every theme, language, and state. If there is motion, offer an equal reduced-motion experience.
Outcome: Use or define CSS Selector to make the visual experience clear and easy to use. User context: A design system selects `[data-state='open']` on a disclosure instead of `.blue-chevron`. A visual redesign does not break it. Where supported, `:has(> input:invalid)` styles a field group with an invalid input. Error text from the server remains the working fallback. Design concept to apply: CSS Selector. Why it fits: Choose stable hooks that describe meaning. Keep specificity as low as useful and avoid depending on an exact DOM depth. Do not use it when: Avoid selectors named after appearance, generated markup, or long child chains. They make later changes risky. Design requirements: Set the content order, shared design values, and reusable components. Define how the layout changes by screen size and state. Keep useful design choices separate from decoration. Inclusion and resilience: Check contrast, zoom, languages, themes, and reduced motion when needed. Do not use color or effects as the only way to show meaning. Acceptance criteria: The design stays clear on phones and desktops, at zoom, in every theme, and in all supported languages. Interactive states stay clear and consistent. Evidence and limits (evidence boundary): A formal document may still be a draft, release candidate, or final version. Check its status and browser or platform support. Unknowns to confirm: Brand limits, amount of content, supported themes and languages, target devices, and design-system rules.
Check this request
Review the current use of CSS Selector. Definition: A CSS selector is a pattern that finds elements on a page so styles can be applied to them. Release checks: Check content order, shared design values, component consistency, contrast, zoom, and layout changes by screen size. Verify every theme, language, and state. If there is motion, offer an equal reduced-motion experience. Before changing code, report the evidence you found, gaps, severity, and the smallest safe fix.