Centre-aligned journal with css

[garedeuropa]

I'd like to have my journal centred horizontally. I find my journal's default layout too wide to read comfortably, so I used body {width:70%;} to narrow it. However, it won't budge from the left side of the screen. I've tried align:center, float:center, and auto left and right margins. Having it all on the left leaves a distracting block of white space on the right, so I'd much prefer the journal in the middle.