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CSS and interface design · Lesson 05 / 12

Measurements that support reading

An interface must remain readable when text grows.

Learning paths14 min

Let's discover together

  1. 1

    Px is a CSS pixel, not necessarily one physical screen pixel. Rem relates to root font size; em depends on the property context. Here 1rem equals 16px only when the effective root font size is 16px.

  2. 2

    Use unitless line-height such as 1.6 to multiply an element’s font size. Max-width limits overly long lines; ch approximates the width of a font’s zero character rather than counting actual letters.

  3. 3

    Prefer automatic height for text cards. Fixed height can clip translations or enlarged text. Overflow-wrap:anywhere helps with long strings, but hiding everything with overflow:hidden does not fix missing information.

  4. 4

    Change font size and width while keeping all content visible. In the workshop, rem belongs to the preview document. In the local file, also test real browser zoom and text enlargement; a narrow screenshot does not cover every case.

Workshop: one interface, different spaces

Edit <style id="lesson-css"> in “My files and GitHub”. The preview applies that CSS to the supplied HTML structure; check HTML edits in the downloaded file. External resources and CSS outside the study subset are not accepted here.

Go to my code

Measurements describe this preview; they do not guarantee every size or complete accessibility. Test long content, zoom, keyboard and assistive technologies in the local project.

Two-color contrast lab

Approximate ratio ·

Calculation only for two opaque sRGB colors selected here; it does not read your page. The threshold uses the unrounded ratio. It does not assess transparency, gradients, images, states or complete conformance.

Official links and next step

✦
YOUR MISSION

Choose units and dimensions that support flexible text.

Now it's your turn

Discovery workshop

Predict, change, compare

The effective root is 16px. A paragraph uses font-size:1.25rem and line-height:1.6.
Build your answers and check when you are ready.
A moment to understand

Is a short fixed height a good solution for different text lengths?

I need a hint

Check the rule, condition and observed result before concluding.

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Take it with you

Compare short and long sentences in the downloaded file, in two languages and with zoom. Record an adjustment preventing clipping.

At your own pace

My files and GitHub

Every lesson can become your own record: code, notes or a practice plan. Saving a file to GitHub is optional and does not change your XP.

Student guide

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