Css vertical tabs

I am trying to use the following to make the tabs smaller on the left but it is not working, please advise.
.su-tabs-vertical .su-tabs-panes {
float: left;
width: 85%;
}
.su-tabs-vertical .su-tabs-nav {
float: left;
width: 15%;
}

Hello there,

The common reason why CSS code won’t work is due to error found in the preceding lines of the mentioned code. To verify, try to validate the group of your CSS code with this tool.

If no error found, this codex might help you find the solution.

Regards,
Kharis

I checked out the tool and found one issue but the css above does not alter the tabs as I wish. I want to make the tab title area smaller, content larger. I was able to adjust the color and font size by using the following:
.su-tabs-vertical .su-tabs-pane {
padding: 15px;
font-size: 16px;
}
.su-tabs-vertical .su-tabs-nav span {
font-size: 16px;
background: #ebeced;
background-color: #f0f3f4
}

Can you please let me know what I am missing to modify the vertical tab layout?
thanks
robert