Q:

Changing the style of leftmost menu item

Here is my Codepen demo which I want to show like image snap below the link:
Codepen Demo
Snap:

I used this css:
.menu > ul > li:first-child {
      color: red !important;
}

To make left most link Red but still it shows Grey line.
Actually it should look like this:

Problem 2: 
The length of the line above alert box should span to entire width of the page. How to do this?
I tried with chaging:
.menu > ul {    
    display: block;    
    list-style: none;    
    border-bottom: 0.1em solid #9e9e9e;
    width: 152%;  // makig it 200% increase width of entire page. Rather I want to increase the width of lie only
    margin-left: -2%;

}

A:

Try this
.menu > ul > li:first-child a {

  color: red !important;
}

DEMO

