Oxygen theme width of dropdown menus

Hello!

I am trying to change a width of dropdown menu in primary menu.
This is the dropdown menu styling that is set up in style.css:

#menu-primary li ul {
	display: none;
	position: absolute;
	top: 25px;
	left: 0;
	border: 1px solid #ddd;
	border-top: none;
	background: #fff;
	z-index: 100;
}

As you can see, there is no width parameter set up but setting one up doesn’t help anything, because whenever I hover the primary menu item which opens its submenu, it adds inline style so it looks like this:
<ul class="sub-menu" style="float: none; width: 12em; visibility: hidden; display: none; ">

Is there any way I could override or change the 12em width? I can’t find where is that 12em width set.

The structure of menu is:

<div id="menu-primary" class="menu-container">
<div class="menu">
<ul id="menu-primary-items" class="">
	<li><a href="">Menu item 1</a></li>
	<li><a href="">Menu item 2 (opens submenu)</a></li>
	<ul class="sub-menu">
		<li><a>Submenu item 1</a></li>
		<li><a>Submenu item 2</a></li>
		<li><a>Submenu item 3</a></li>
	</ul>
	<li><a href="">Menu item 3</a></li>
</ul>
</div></div>

Thank you! I hope I have provided all the details needed ??

https://www.ads-software.com/extend/themes/oxygen/