Question 1

What is the difference between px, rem, and em?

Accepted Answer

px is an absolute unit (1px = 1 device pixel at 96 DPI). rem is relative to the root font size (usually 16px, so 1rem = 16px). em is relative to the parent element font size. rem is preferred for accessibility.

Question 2

Why should I use rem instead of px?

Accepted Answer

rem respects user browser settings. If a user sets their default font size to 20px for accessibility, rem-based layouts scale accordingly, while px stays fixed. This makes your site more accessible to visually impaired users.

Question 3

How do I convert px to rem?

Accepted Answer

Divide the px value by the root font size (default 16px). For example: 24px / 16 = 1.5rem. 12px = 0.75rem. 32px = 2rem. You can change the root size with html { font-size: 18px; } to adjust the scale.

Question 4

What is the difference between pt and px?

Accepted Answer

pt (points) is a print unit: 1pt = 1/72 inch. px (pixels) is a screen unit. At 96 DPI (standard screens), 1pt = 1.333px. Use pt for print stylesheets and px/rem for screen. 12pt text = 16px on screen.

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