I would like you to try this demo here: https://davidwalsh.name/demo/background-size.html which would explain how background image works.
We use the
background-image: cover; which would cover the whole area of the container. This is responsive enough which will always covers the whole area. The only thing to consider here is that if your image size is smaller, it will be stretch out and if you have a bigger image, it will get cut off.
Yes we can use
background-size: 100% 100%; which is also responsive but your image will either be stretch out or get squeezed depending on the size of the container.
Yes we can also use
background-size: 100% auto; but then as soon as you resize your browser or on smaller screen sizes, you will probably have white spaces around the image.
Or we can also use
background-size: contain; but then this is not a good choice because you will see white spaces around your image.
Be advised that the background image size depends on the height of the section which is also dependent on the total height of the row which in turn, also dependent on the total height of the column. This is why we add
vh means “Viewpoint Height”. You can check it more about it here: https://www.sitepoint.com/css-viewport-units-quick-start/
By the way, if you do not want the background image to
zoom-out and you do not have any text contents on top of the background image, it is best that you use the image as an element inserted in the column. Having this way, the image will always display correctly depending on its dimension. If you want, you can give us access to your site so we can give you an example.
Hope this helps.