html - Divs are going out of the parent div -

html - Divs are going out of the parent div -

i'm working on webpage.

basically it's 2 sections. main section taking of screen sidebar on right isn't. sidebar fixed , set 250px wide. main section set 100% width margin-right of 250px.

now set downwards few test blocks see how look, they're 300px x 300px. can see, lastly block on top row goes behind sidebar. how can create go next line instead of going behind sidebar?

thanks in advance.

maybe reason width: 100% main section?

.main { width: auto; margin-left: 250px; }

html css margin hidden behind