Problem: I would like to use my own custom CSS and turn off the Toolset Starter Theme CSS, and I would like to use Bootstrap 4.
Solution: You may deactivate Toolset Starter Theme CSS by going to Appearance > Customize > Advanced Settings. Edit your child theme to dequeue Bootstrap and re-enqueue it using your own Bootstrap 4 styles.
Problem: I would like to use a custom field image as the background for each item in a loop, but for some reason the last loop image is applied to all loop items.
Solution: We do not recommend creating style tags in the Loop Output:
<style>...</style>
Since CSS is parsed all together and not iteratively, only the last style tag will be respected. All the others will be overridden. This is how CSS works, it is not a bug. Instead of creating style tags in the loop, consider adding overriding styles to an individual element in the loop: