Why is the gradient not displayed and padding(!) Collapsing in IE?

Question

css

the block is given vertical padding and a gradient to the background. in the donkey, the background is not displayed (I also tried to put a solid fill), and if you look in the inspector, then the paddings are on top of neighboring blocks. if there is nothing around the block, then the paddings simply disappear. in fact, the donkey simply ignores all the rules specified in the css for this block.
Link to the project prilovski.ru/eventfeed

Answer 1

All figured out. IE does not understand the tag had to be replaced with div.main

Answer 2

Use the HTML5 Shiv library to make IE understand the tags