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Ivan Uvarov
22,403 PointsStrange use of em
I have a question about this specific video.
I cannot see the reason to use em function (divides target by context) here.
Instructor sets h1's font-size to be em(42px). Then when calculated this value will be 2.625em (given that the base font-size equals 16px). However, if we then change base font-size to, say, 21, the value will be recalculated and will be 2em. Both 2.625em and 2em in this case will render as the same size on a page, which basically means that rendered font-size of h1 will always be the same, independent from the base font-size. This ruins the whole purpose of using ems: they used to make font-size to be responsive.
When you set font-sizes with ems or rems, and then change base font-size, all font-sizes should scale proportionally. But in this example nothing will scale. So what's the purpose of use ems instead of pixels here?
1 Answer
Guil Hernandez
Treehouse TeacherHi there,
The h1 font-size will scale proportionally since the em() function divides the px target by the $base__font-size variable by default.
Ivan Uvarov
22,403 PointsIvan Uvarov
22,403 PointsBut if you change the value of
$base__font-size, em value for h1 will be recalculated accordingly, and as a result rendered size of h1 won't change. em values should always stay the same, but here they will be recalculated every time you change the value of$base__font-size.Guil Hernandez
Treehouse TeacherGuil Hernandez
Treehouse TeacherRight on. In that case, you wouldn't change
$base__font-sizeforh1so that it always scales to the base size. You can see similar functions here.These are all suggestions—you can also just stick
emunits. :)Brendan Whiting
Front End Web Development Techdegree Graduate 84,738 PointsBrendan Whiting
Front End Web Development Techdegree Graduate 84,738 PointsI still don't get why you would use this strategy. Is there a benefit to having the css output be in em values? Like for accessibility when people change their base font size?