If you are not familiar with Wine (or maybe even if you are), you may find the article Understanding Wine helpful. A more complete reference is the WineHQ Wine User's Guide. Also see the Wine List of Commands.
Install Wine on Manjaro 18
Majnaro includes Wine in its repositories, which makes installing Wine easy. Begin by opening System > Add/Remove Software and searching with the keyword wine. For a complete installation, select the following packages, and, when asked about "optional dependencies", consider selecting all unless you have a specific reason not to.
In the past, selecting wine installed a recent development version of Wine, while selecting wine-staging installed a recent staging version. At the time this page is being updated, Wine 5.0 is recently released, and both options install Wine 5.0.
After selecting the above, click Install and Apply.
As soon as installation of all packages is complete, open a Terminal window and issue the following command to verify a successful installation.
$ wine --version
Now that Wine is installed, take a look at the article Using Wine for information on installing Windows applications.
There is also an article CSS HTML Validator installation with Wine which contains specific instructions for installing and configuring CSS HTML Validator.
Wine ArchWiki (Manjaro is derived from Arch Linux)