Bootstrap might be a great way to get started quickly. However, sometimes, developers get lazy and do not bother to change the default look. This leaves a poor impression on your users who might find your site's appearance a little too familiar and uninteresting.

Bootstrap 4 comes with plenty of options to improve its visual appeal. You can create a file called custom.scss where you can customize everything from theme colors to grid breakpoints. The documentation explains how you can set up the build system to compile these files down to the style sheets.

Thanks to the huge community around Bootstrap, there are also several sites, such as bootswatch.com, which have themed style sheets, that are drop-in replacements for your bootstrap.min.css.

Last but least and least, you can make your CSS classes more meaningful by replacing structural class names, such as row or col-lg-9, with semantic tags, such as main or article. You can do this with a few lines of SASS code to @extend the Bootstrap classes, as follows:

@import "bootstrap"; 
 
body > main { @extend .row; 
  article { @extend .col-lg-9; } 
} 

This is possible due to a feature called mixins (sounds familiar?). With the SASS source files, Bootstrap can be completely customized to your needs.