Please help! Posts are inexplicably indenting / shifting to the right

Hello,

On my main page, the margins are great and the post excerpts look fine (http://www.asherworldturns.com/). But when you click on a link to go to a post, suddenly the text and photos appear to be indented, which causes all the horizontal photos to look distorted and skinny (e.g. http://www.asherworldturns.com/a-heavenly-day-of-skiing/).

When I increase the page max-width in my child theme, it fixes the photo sizes in the post, but then it makes my header photo too big. Plus it doesn’t change the fact that the entire post is indented. If the post were flush left (like the excerpts on my main page), it should work fine, but I can’t figure out how to make that happen. I tried adding this to my child theme but it didn’t change anything:

.post p { text-align:left; }
.page p { text-align:left; }

I am very new to this and would appreciate any help!

–Erica