I'm a newbie and I couldn't get the Include the Pledge instructions from @nonlinearone's otherwise *awesome* Power Up SteemIt! Make The Power Up Pledge post to work in any browser (see that post for why you definitely should take the pledge).
Here is how I got it to work in both Firefox and Chrome:
Click on Raw HTML hyperlink on the right side of the editor menu bar to go to Raw HTML mode (it looks scary but it really isn't -- and step 4. will return you to the normal editor mode)
Go to the bottom of the post
Just before the </html>, paste the following: <strong><a href="/trending/poweruppledge">#poweruppledge</strong></a><strong</a>: I pledge to power up </strong><img src="https://www.steemimg.com/images/2016/08/08/klye-mushroom69c9a.png" /><strong> every STEEM DOLLAR <img src="http://puu.sh/qtqFm/4f2ebbc66d.png"/><strong> earned from this post to STEEM POWER <img src="http://puu.sh/qr89B/deac53342f.png<a href="https://steemit.com/steemit/@nonlinearone/power-up-steemit-make-the-power-up-pledge-poweruppledge"><strong>Join the #poweruppledge movement!</strong></a><strong>!</strong></p>
replace the REPLACE_ME with https://www.steemimg.com/images/2016/08/08/klye-mushroom69c9a*png and change the * to a period
Click on the Editor hyperlink that has replaced the Raw HTML link to return to normal editor mode
Check out your shiny new pledge at the bottom of your post
HINT: Using the Test tag to create a test copy of your post is *highly* recommended if you are not sure of the formatting of your post (like I apparently wasn't -- DOH!)