background-color: red; text-align: center; text-decoration: overline; text-indent: inherit; text-overflow: inherit;
in the image you see: (it may be a package that is necessary, I had not had this before)
The same thing happened to me some time ago.
Atom defaults to the extension of your file (.css .html .php, etc) and likewise applies pre-set colors to the syntax.
If this does not happen automatically, or is like plain text, you can change it as follows.
Below the whole to the right you will see the section where the language to be used is specified and therefore to mark (in the example, plain text)
By clicking on that option, you can change the type of language that will be applied in the syntax, you can see that they are several.
Finally, choose the one you want to use (you can make this change manually as many times as you wish). As a recommendation, and if not, leave Auto Detect
I was left wandering your question in the mind, and I realize that I had not tried to reproduce exactly your CSS code in my Atom editor; To my surprise, the same thing happens in your image:
This happens because Atom ( by default ) highlights in color ( in CSS files in this case ) only the classes, the color values ( hexadecimal, RGBA, etc ), the number values (
.rem , etc), duration values (
ms , etc), the pseudo-classes and the pseudo-elements (
::before , etc) among others.
Does not highlight or color properties with values such as
absolute and many more values of type "text".
You can validate yourself, for example, by viewing the Bootstrap stylesheet in Atom.