css menu disappears on mobile device - html

Question

Here's my CSS menu I've created.
When I see this in my mobile (iPhone 6), the last menu (Menu4) does not show At All. The first 3 menus stretch from left to the right of the phone screen. I can't figure out why.
Could someone help out please?
Here's the HTML part
<hr class="navHr">
<nav id="m">
Menu1
Menu2
Menu3
Menu4
</nav>
<hr class="navHr">
And the CSS part
.navHr {
border: 0;
height: 0.1em;
margin: 0;
background-image: -webkit-linear-gradient(left, rgba(0,0,0,0), rgba(0,0,0,0.75), rgba(0,0,0,0));
background-image: -moz-linear-gradient(left, rgba(0,0,0,0), rgba(0,0,0,0.75), rgba(0,0,0,0));
background-image: -ms-linear-gradient(left, rgba(0,0,0,0), rgba(0,0,0,0.75), rgba(0,0,0,0));
background-image: -o-linear-gradient(left, rgba(0,0,0,0), rgba(0,0,0,0.75), rgba(0,0,0,0));
}
nav {
height: 2em;
background: #000;
background: linear-gradient(to bottom, rgba(76, 76, 76, 1) 0%, rgba(44, 44, 44, 1) 50%, rgba(0, 0, 0, 1) 51%, rgba(19, 19, 19, 1) 100%);
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#4c4c4c', endColorstr='#131313',GradientType=0 );
line-height: 2em;
text-transform: uppercase;
text-align: center;
min-width: 2em;
position: relative;
}
nav::before {
background: linear-gradient(to top, rgba(76, 76, 76, 0) 0%, rgba(44, 44, 44, 1) 50%, rgba(0, 0, 0, 1) 51%, rgba(19, 19, 19, 1) 100%);
content: '';
display: block;
position: absolute;
top: 100%;
left: 0;
width: 100%;
height: 100%;
opacity: 0.09;
}
nav a {
color: #FFF;
text-decoration: none;
font-weight: bold;
font-size: 1.2em;
border-right: solid 0.1em #FFF;
height: 100%;
padding: 0.25em 3em;
position: relative;
}
nav a:first-child {
border-left: solid 0.1em #FFF;
}
nav a::before {
content: attr(data-mirror);
position: absolute;
top: 100%;
left: 3em;
color: #000;
transform: scaleY(-1);
color: #FFF;
opacity: 0.5;
}
#m {
background-color: #000000;
}

Answer 1

I've checked on your code, try adding "display:inline-block" on your anchor tag, and you will see your column 4 appearing, the fourth one goes beneath the second one in small screens, since the position is relative, try it here :
Columns
Basically, what you are looking for, is displaying an element as an inline-level block container to avoid dislocation. The inside of this block is formatted as block-level box, and the element itself is formatted as an inline-level box, which shapes the navigation of these 4 columns sitting next to each other.
Why do we use inline-block ?
Inline-block makes the element generate a block box that’s laid out as if it were an inline box.
An inline block is placed inline (ie. on the same line as adjacent content), but it behaves as a block.
Basically, it’s a way to make elements inline, but preserving their block capabilities such as setting width and height, top and bottom margins and paddings etc.