Em and rem resources from Kevin Powell

• 19 October 2025
• css

I've started Kevin Powell's Conquering Responsive Layouts course. In one of the first lessons, he talks about units of measurement, specifically pointing out em vs rem. He recommended 2 of his videos:

• CSS em vs rem explained - Youtube, 2017 and
• Why you shouldn't set font-sizes using em - Youtube, 2019

These are very good to grasp the fundamentals of when to use ems and rems. From what I understood:

• rems are useful when you want things to scale up relative to the whole document
• ems are useful when you want things to scale with your parent element; for example, a button's padding should grow relative to its font size to maintain the look and ratio of the text
• don't set font-sizes in ems because it can compound in children elements, and end up with massive sizing

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