Contrast on disabled inputs

Hi,

When setting the disabled attribute on text fields in the Perch UI it appears the contrast between the value and background of the field is very low, making it very difficult to read. This is problematic on slug fields when using the indelible tag.

This is how it appears on Safari with v3.0.11:

A possible suggestion could be to add a padlock icon onto the right of the field to indicate that it is no longer editable.