css - Fix font size issue on Mobile Safari (iPhone) where text is rendered inconsistently and some fonts are larger than others?

Question

Our site renders with inconsistent font sizes on mobile Safari -- and as far as we can tell, only Mobile Safari. This very much has stumped us.

We analyzed the site with Firebug, and the incorrect areas are inheriting the right styles, yet the fonts are still rendered with the wrong sizes.

1) Visit http://www.panabee.com.

2) Conduct a search for a domain name.

The boxes on the left side show the incorrect font sizes. The font size should match the font size on the right side (both box titles and box copy). For instance, the titles, "Variations" and "Twitter," are much larger than the title, "Alternate Endings."

Any clue why?

Answer 1

Mobile Safari (like Chrome for Android, Mobile Firefox and IE Mobile) increases the font size of wide blocks (at all times), such that if you double-tap to zoom in on that block (which fits the block to the screen width), the text will be legible. If you set -webkit-text-size-adjust: 100% (or none), it won't be able to do this, and so when a user double-taps to zoom in on wide blocks the text will be illegibly small; users will be able to read it if they pinch-zoom in, but then the text will be wider than the screen and they'll have to pan horizontally to read each line of text!

1. Ideally you would fix this by using Responsive Web Design techniques to make your design adapt to mobile screen sizes (in which case you would no longer have any very wide blocks, so mobile browsers would no longer adjust your font sizes).

2. If that's not an option, and you're stuck serving a desktop site to mobile users, then see if you can tweak your design so none of your blocks of text are wider than the mobile device's device-width (e.g. 320px for many portrait phones) (you can use mobile-specific css to avoid affecting desktop browsers), then Mobile Safari won't need to increase any font sizes (and browsers which reflow text, like the Android Browser and Opera Mobile, also won't need to change your layout).

3. Finally if you really need to prevent Mobile Safari from adjusting your font sizes you can set -webkit-text-size-adjust: 100%, but do this only as a last resort since it is likely to cause mobile users to have difficulty reading your text, as it'll either be too small or they'll have to pan from side to side after every line they read. Note that you must use 100% not none because none has nasty side-effects in desktop browsers. There are also equivalent -moz-text-size-adjust and -ms-text-size-adjust properties for Mobile Firefox and IE Mobile.

Edit: for example in your case the simplest is probably the 2nd alternative, so you could try adding the following CSS:

/* Mobile browsers only */
@media only screen and (max-device-width: 480px) {
    table#all_results {
        width: auto;
    }
    td#main_box {
        width: 320px;
    }
    td#side_box {
        width: 320px;
    }
}

Though it's not ideal to hardcode 320px like this; you could improve on that by using a variety of CSS media queries, or getting the device-width from JavaScript.