Introduction
Important globals
Bootstrap employs a handful of important global styles and settings that you’ll need to be aware of when using it, all of which are almost exclusively geared towards the normalization of cross browser styles. Let’s dive in.
HTML5 doctype
Bootstrap requires the use of the HTML5 doctype. Without it, you’ll see some funky incomplete styling, but including it shouldn’t cause any considerable hiccups.
<!doctype html>
<html lang="en">
...
</html>Responsive meta tag
Bootstrap is developed mobile first, a strategy in which we optimize code for mobile devices first and then scale up components as necessary using CSS media queries. To ensure proper rendering and touch zooming for all devices, add the responsive viewport meta tag to your <head>.
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">You can see an example of this in action in the starter template.
Box-sizing
For more straightforward sizing in CSS, we switch the global box-sizing value from content-box to border-box. This ensures padding does not affect the final computed width of an element, but it can cause problems with some third party software like Google Maps and Google Custom Search Engine.
On the rare occasion you need to override it, use something like the following:
.selector-for-some-widget {
box-sizing: content-box;
}With the above snippet, nested elements—including generated content via ::before and ::after—will all inherit the specified box-sizing for that .selector-for-some-widget.
Learn more about box model and sizing at CSS Tricks.
Reboot
For improved cross-browser rendering, we use Reboot to correct inconsistencies across browsers and devices while providing slightly more opinionated resets to common HTML elements.