ID Selector

Basic

#idname

Selects the element with the specified ID. Very high specificity — use sparingly to avoid specificity conflicts.

Example

#header {
  position: sticky;
  top: 0;
  z-index: 100;
}

Specificity

0-1-0-0

Browser Support

All browsers

About the ID Selector

The #idname CSS selector belongs to the Basic category.Selects the element with the specified ID. Very high specificity — use sparingly to avoid specificity conflicts. Understanding CSS selector specificity and combinators is essential for writing maintainable stylesheets that behave predictably.

The specificity of this selector is 0-1-0-0. CSS specificity determines which styles are applied when multiple rules target the same element. Higher specificity values take precedence. The specificity hierarchy from lowest to highest is: universal (*) → type/element → class/attribute/pseudo-class → ID → inline styles → !important.

Browser support for ID Selector is: All browsers. When using newer CSS selectors like :has(), :is(), or CSS nesting, consider providing fallback styles for older browsers. Use @supports to progressively enhance your stylesheets with modern features while maintaining backward compatibility.

Related Selectors

.classname element *