Border Width

Hi there

Love your plug-in, it works faultlessly for me every time. I’ve recently changed theme and am trying to align the TOC with theme style, particularly border radius and width. I have no idea about CSS really but used this snippet which works for the radius but does not change the border width, am I doing something wrong or is there something in the plug in to stop any changes to border width? I have tried variations, using ‘solid’ in front of and after 3px, but nothing seems to make a difference. Many thanks

#ez-toc-container { ?
? ?border-width: 3px;
border-radius: 0px;
}