localhost install with XAMPP error

It might not be too difficult to fix. You need more specific information beyond it being a critical error. Go to the Apache error.log file from your XAMPP control panel. What errors were logged at the time you got the critical error message?

If the error is due to a plugin or theme file, disable that module by renaming its folder through your normal file system UI.

“There has been a critical error” is not much to go on by itself, hence the lack of meaningful debugging information. Sadly, on public sites, showing more specific information can give hackers useful feedback so more detail has been suppressed. If your localhost is inaccessible from outside, WP can be configured to show more meaningful information in case of error.

32 bit is pretty unusual these days, but I know of no reason it wouldn’t still work.

The error log is important for coding if the site is not configured to display error messages. In the XAMPP control panel, click the Apache “Logs” button. Select “Apache(error.log)”. The most recent errors are added to the end of the file that opens.

If it’s safe to display errors on the site (no public access possible), you can do so by defining ‘WP_DEBUG’ as true in wp-config.php. You can suppress the “critical error has occurred” routine in favor of directly displaying errors by adding define( 'WP_DISABLE_FATAL_ERROR_HANDLER', true ); right below the debug definition.

There are a number of ways CSS can be applied to a page beyond style.css. One could use the @import statement in a CSS file, though that’s discouraged in WP. We should be loading files with the wp_enqueue_style() PHP function. Inline CSS can be added by anything that sends output. Individual HTML tags can contain style attributes, though this really should be avoided at all costs because such rules are very difficult to override when the need arises.