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srcset and picture look like two ways to do the same job. They are not: srcset lets the browser choose a size of the same image, picture lets…

A flex item refuses to shrink below its content, because min-width defaults to auto on flex items rather than to zero. The symptom is a long word or…

position: sticky works or does nothing, with no error and no warning. Nearly always the cause is an ancestor rather than the element itself. The overflow rule is…

100vh is defined against the viewport with the browser chrome hidden. On iOS Safari the address bar is visible until the user scrolls, so a full-height hero is…

:nth-child(2) means “the second child, and only match if it is also this element type”. :nth-of-type(2) means “the second one of this element type among its siblings”. They…

The default box model adds padding and borders outside the width you set, so a column declared at 25% with 10px of padding is not 25% wide. Every…

Fitting a user-uploaded image of unknown aspect ratio into a fixed box has always meant a wrapper with overflow: hidden, the image absolutely positioned, and a centring translate.…

CSS has no other way to say “the full width minus the sidebar” when one side is a percentage and the other is fixed. The old answers were…