Always use mono-space font for Chrome input fields

nb: this answer is now redundant as Chrome has removed support for user style sheets. I'd suggest dear reader to refer to the other answer, although I haven't tested it myself.

You could add a rule along the lines of

textarea { font-family: monospace !important; }

to your user stylesheet.

I found this post explaining where to find that file on common operating systems:

For Chrome, you need to find the Custom.css file. On Windows Vista/7/2008, it is located at the following (replace with, ahem, your user id):

C:\Users\<your-userid>\AppData\Local\Google\Chrome\User Data\Default\User StyleSheets\

[Presumably on Windows XP it will be under C:\Documents and Settings\ in a similar location.]

For Mac OS X, it is at:

~/Library/Application Support/Google/Chrome/Default/User StyleSheets/

On Ubuntu Linux it is found here:

~/.config/google-chrome/Default/User StyleSheets

You can use the Stylish add-on (for Firefox or Chrome), which enables you to specify custom CSS stylesheets for any website.

To make all pages use monospace fonts:

• Install Stylish
• Click the Stylish icon
• Click “Create New Style”
• Paste the code textarea { font-family: monospace !important; }
• At the bottom of the screen, set to which URLs it should apply
• Click “Save” on the left

If you want a global style that applies to all websites, you should include the code

/* i really want this to be global */

in your stylesheet, per the Stylish help.