"The text content in the third box is longer than the available space, so rather than maintaining the aspect ratio, the element expands vertically to fit the content... If we set an explicit height instead, the element doesn’t expand, but instead we get overflow"
Why? Why would you have different default behaviours if you have one of the dimensions set but not the other? Why would you not have this specified in another property, the overflow property perhaps? Oh look, lets define a new property and call it aspect ratio, and then lets ensure it doesn't maintain an element's aspect ratio if you have content that is going to overflow if you specify a width. This is what drives me mad about css, it's gotchas all the way down.
Why? Why would you have different default behaviours if you have one of the dimensions set but not the other? Why would you not have this specified in another property, the overflow property perhaps? Oh look, lets define a new property and call it aspect ratio, and then lets ensure it doesn't maintain an element's aspect ratio if you have content that is going to overflow if you specify a width. This is what drives me mad about css, it's gotchas all the way down.