Disabling spell check in HTML forms

I work with DNA and protein sequences and I often have HTML forms with a textarea for entering sequence. Unfortunately my browser sees that text (e.g. 'agctagagctcgatagc') and decides that this is misspelled and underlines all the sequence text with a red dotted line... ugly...

In HTML5 you can now disable spell checking on textarea and text inputs using the option 'spellcheck' = 'false' - EASY!

Note that this is a HTML attribute, NOT CSS - so you have to set it in the form itself.

Browser support for the feature may vary. It works on Firefox and Safari on the Mac for sure.

A related attribute is 'contenteditable' that allows you to control whether specific parts of a textarea's content can be modified - like 'readonly' but with much more control.