Layout and responsive · Lesson 8 of 14 · 10 minutes

Layout and responsive: Content-width constraints

A width cap keeps long lines readable while inline padding protects small viewports.

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Your objectives

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1
Build content-width constraints
Build this first target: main with max-width: 65ch. Keep the selector relationships intact and inspect the preview.
Hint & worked example
A width cap keeps long lines readable while inline padding protects small viewports.
The requested selectors and declarations exist outside comments.
```
main { max-width: 65ch; }
```
Common mistake to avoid: If the page fits one desktop viewport, no narrower viewport needs checking.
2
Extend the content-width constraints example
Extend your file to include: main with max-width: 65ch; main with margin-inline: auto. Keep the selector relationships intact and inspect the preview.
Hint & worked example
A width cap keeps long lines readable while inline padding protects small viewports.
The requested selectors and declarations exist outside comments.
```
main { max-width: 65ch; }
main { margin-inline: auto; }
```
Common mistake to avoid: Hiding all overflow always makes content accessible.
3
Verify the complete content-width constraints pattern
Finish the pattern with: main with max-width: 65ch; main with margin-inline: auto; main with padding-inline: 1rem. Keep the selector relationships intact and inspect the preview.
Hint & worked example
A width cap keeps long lines readable while inline padding protects small viewports.
The requested selectors and declarations exist outside comments.
```
main { max-width: 65ch; }
main { margin-inline: auto; }
main { padding-inline: 1rem; }
```
Common mistake to avoid: If the page fits one desktop viewport, no narrower viewport needs checking.

Understand the pattern

A width cap keeps long lines readable while inline padding protects small viewports.

Misconceptions to reject

If the page fits one desktop viewport, no narrower viewport needs checking.
Hiding all overflow always makes content accessible.

The preview is a sanitized subset, not a full browser compatibility test.

Worked example and expected result

main { max-width: 65ch; }
main { margin-inline: auto; }
main { padding-inline: 1rem; }

A width cap keeps long lines readable while inline padding protects small viewports.

Try a variation

Adapt the final example to a different project name while retaining its structure and relationships. A different context still needs a real browser and accessibility check.

Explain it

Which statement correctly explains content-width constraints?If the page fits one desktop viewport, no narrower viewport needs checking.Hiding all overflow always makes content accessible.A width cap keeps long lines readable while inline padding protects small viewports.

Apply it elsewhere

You reuse content-width constraints in a different project. What must still be verified?Only whether the source code has the same number of lines.The resulting layout, focus behavior, and readability at the target viewport sizes.Nothing; passing a single exercise guarantees every future use.

Keep the momentum.

Complete the lab, then explain and apply the pattern.

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MDN: CSS styling