If you're not able to see the changes you just made to your Thesis theme design and layout, the chances are you've forgotten to resume Design Mode.
Design Mode was introduced in Thesis 1.8.4.
It's a limited form of minification because it combines the style.css, layout.css and custom.css files into one in order to speed up page-load time.
Design Mode is active by default but, once you've completed setting up your design and layout, you can switch it off to combine those files and speed up the page-load time of your site.
Some people (me included – on several occasions!) have been caught out by this, though. If you switch off Design Mode and then later make a change to your design or layout without resuming it, your changes won't show up.
To correct this you need to resume Design Mode before making your changes and then switch if off again when you’re finished.
Step 1: Switch off Design Mode
When you’ve completed your design and layout you can switch off Design Mode in the Stylesheet Options of the Site Options screen – simply un-check the check box:
Step 2: Resume Design Mode
Before making any changes to your site using the custom.css file, the Site Options or the Design Options screens, resume Design Mode by re-checking the check box.
Once you’ve completed your changes you can then switch Design Mode off again.
Step 3: Make sure you hard refresh your page
Finally, after resuming design mode you may find your layout and design is all messed up when you check the front of your site. Just hit F5 (hard refresh on Windows machines) and all will be fine.
That’s all there is to it 🙂