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Email Development

CSS Targeting for AOL Mail

Email On Acid

Among webmail clients, I would say AOL Mail is the most friendly when it comes to processing CSS. Unlike Gmail and Yahoo! Mail, AOL Mail allows a lot more CSS styles and it allows developers to be more adventurous with their designs in AOL Mail. This is especially true for advanced CSS like animation and absolute positioning.

However AOL Mail has its own quirks so its important to be able to target AOL Mail in our CSS styles so we can address this client.

Targeting Techniques

The star or unicode id and class name technique

Mark Robbins discovered a clever hack to target AOL Mail using unicode characters in class names. You can use the following selector to target AOL Mail, by putting the same unicode character as the id and class of an element and then creating a selector that will match a class with the unicode character but not the id.

<style>
.★:not(#★){
  background-color:red;
}
</style>
<div class="★" id="★">TEST</div>

The attribute selector technique

AOL Mail appends aolmail_ to classes and ids as well as CSS selectors including exact attribute selectors (x=y). However it doesn't append aolmail_ to other attribute selector types (x~=y, x^=y, x$=y). So we can target a selector to be only active in AOL Mail by using an attribute selector like (~=) and manually appending the aolmail_ string to the class name.

<style>
div[class~="aolmail_foo"]{
  background-color:red;
}
</style>
<div class="foo">TEST</div>

AOL Mail does not support "for" attribute in labels

The question now, is why would we target AOL Mail? One key reason to target AOL Mail is that AOL Mail responds to common techniques we use to test for interactive email support, yet there are certain capabilities that are not supported by the client.

Specifically there are certain cases where methods we use to test for interactive support will "pass" in AOL Mail (using the -webkit-min-device-pixel-ratio media query and the checked checkbox technique) yet AOL Mail does not support the techniques used. For example, AOL Mail does not support techniques using the "for" attribute in labels which means that we need a way to hide interactive content using the "for" attribute in AOL Mail.

We can selectively hide the interactive block in AOL Mail with the "aolmail_" string in an attribute selector technique described earlier

<style>
@media screen and (-webkit-min-device-pixel-ratio: 0) {
  .cbox-support:checked ~ .interactive{
      display:block!important;
  }
  /*   Hide interactive portion from AOL Mail */
  input[class~="aolmail_cbox-support"]:checked ~ .interactive{
    display:none !important;
  }
}
</style>
<input type=checkbox class="cbox-support" style="display:none" checked>
<div class="interactive">INTERACTIVE</div>

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About the Author

Justin Khoo

Justin Khoo

Justin Khoo (@freshinbox) is an email developer and writes about email techniques and new innovations. He has been involved in many aspects of email over the past decade, everything from building webmail clients and email campaign services to coding HTML emails.

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