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HTML/CSSBeginner#css#flexbox
HTML/CSSIntermediate#css#layout-puzzle#grid
How do you implement a full-height sticky sidebar next to scrolling content?
Use CSS Grid or Flexbox for the two-column layout, then set position: sticky with top: 0 on the sidebar so it stays in view while the main content scrolls past it, as long as the parent isn't shorter than the sidebar.
Example
.layout { display: grid; grid-template-columns: 250px 1fr; }
.sidebar { position: sticky; top: 20px; align-self: start; height: fit-content; }