css

Here is a pretty big hint:

you are going to have to select all images with a

img { }

selector. Inside the selector you need to use the max-width attribute and set that using a percentage

To add on to Stone's answer, the syntax may need to match the exact element you're targeting. So, let's say you want to target only the image inside the div with class "image".

You'll want to use the syntax

ParentElement TargetElement { max-width: % }

So,

div.image img { max-width:100% }

In this example, the div.image would be the parent element and the img would be the target element. It's more likely that if you want an image to fill it's parent element, it won't be a global instruction; you'll just want that one image to fill, then other other images aren't affected. If you just use img { max-width: % } it will affect all images.

Then again, you could set this as the default global property for img and then change on a more specific selector for other images.