In theme/css/ folder find qm-style.css (qm-style-rtl.css if your site is RTL)
In stylesheet find below code. It could be more than one time.
.qa-main {
width:730px;
clear:left;
float:left;
}
Remove clear:left
and float:left
so code should be something like below
.qa-main {
width:730px;
}
If you are familiar with compass and sass than you may like to use that instead of directly modifying production stylesheet.
For that you can use provided raw-content in package bundle.
Once you setup compass and sass for that than find _responsive.sass
file in row-content/sass/components/ folder
In this file you will find .qa-main
class at line #1202 and #1252
Remove clear:left
and float:left
and done.
This should resolve the issue.