How to Adjust Background Image Opacity in CSS

CSS doesn't allow changing background image opacity without affecting child elements. Two workarounds exist: using an absolutely positioned img element with opacity behind the content, or using a ::before pseudo-element with background-image and opacity. Both methods rely on positioning and stacking context to layer a transparent background behind opaque content. The pseudo-element approach supports background properties like background-size and background-position, while the img approach is simpler but less flexible. Common pitfalls include forgetting the content property on pseudo-elements, incorrect z-index stacking, and applying opacity to parent containers instead of background layers.