CSS Mastery – SAD Maintenance and CSA Stand Ups Practice Test 2026 - Free CSS Mastery Questions and Study Guide

Container queries adapt internal styles based on the size of a specific element. The essential step is to mark that element as a container by setting a container-type (such as inline-size) on it. Once the container is designated, you can use @container rules to adjust the internal styles as the container’s size changes. Without declaring container-type, there’s nothing for the container query to observe, so the inner styles won’t respond to the container’s size. Other options don’t establish this container to observe; they rely on global viewport metrics rather than the container’s own dimensions.