Building on @anroesti's excellent hack, here's a solution if you need to apply in unknown contexts in terms of font size and color, i.e. you are not sure if resetting to color:black;font-size:1rem; will not mess things up:
<span abbrev-content="Intl.">International</span>@media only screen and (max-width: 700px) { /* very narrow viewports */ span[abbrev-content] { font-size: 0.001em; visibility: hidden; } span[abbrev-content]::before { content: attr(abbrev-content); font-size: 1000em; visibility: visible; }}If your span content is a paragraph and not just a word, you may also need the negative letter-spacing.