I came across this issue when I was attempting to use an HTML <figcaption> element underneath an image on an iPhone 5s using Safari and Chrome. In portrait view, the font size of the caption does not change, even if explicitly setting a font size in CSS to a size. This may be due to the fact that browsers on an iPhone will automatically increase the size of small text. See the initial HTML and CSS below.

CSS

figcaption {
	font-style: italic;
        font-size: 0.5rem;
	text-align: right;
	margin-bottom: 25px;
}

HTML

<figure>
  <img src="http://image.jpg" />
  <figcaption>Photograph courtesy of John Smith, 
    <a href="http://www.website.com">www.website.com</a>
  </figcaption>
</figure>

With my font-size explicitly set to 0.5rem in CS, the figcaption pretty much takes up the entire width of page, when attempting to align it to the right at a smaller screen size in portrait mode.

In portrait mode, the figcaption almost spans entire width of layout (not what we want).

The figcaption in the landscape version (aligned to right and font-size relative to layout) is the desired outcome.

In landscape mode, the figcaption looks just the way we want it to.

Solution

It turns out that this happens because browsers on smartphones lays out the web page using a viewport that is wider than the device screen, unlike a desktop browser. Therefore using the -webkit-text-size-adjust property does the trick. After applying the property to our CSS, it should look like this below.

CSS

figcaption {
	font-style: italic;
        font-size: 0.5rem;
	text-align: right;
	margin-bottom: 25px;
        -webkit-text-size-adjust: 100%;
}

Be sure not to use “none” as the value for -webkit-text-size-adjust since it can affect how the text will be resized when using zoom in a browser. This would affect desktops as well. See the image below for how the figcaption now looks after adding this rule. Click on the image to see a larger version.

after adding -webkit-text-size-adjust property to our CSS, the figcaption renders the way we want it to (font-size) and now is aligned to the right