#box-sizing

#box-sizing

What does stretch do? The quick answer is that stretch does the same thing as declaring 100%, but ignores padding when looking at the available space. In short, if you've ever wanted 100% to actually mean 100% (when using padding), stretch is what you're looking for: div { padding: 3rem 50vw 3rem 1rem; width: 100%; /* 100% + 50vw + 1rem, causing overflow */ width: stretch; /* 100% including padding, no overflow */ }