CSS dropdown menu cross-browser

Question

My CSS dropdown menu behaves strange in different browsers. It works fine in Chrome (Windows) but there are issues in Firefox and on Android.

Firefox: Dropdown menu opens up to the right of the menu item instead of below. Also, the dropdown menu is not in line with the menu item because of the padding I used in '#naviagtion ul li ul' to prevent it from clipping with '#navigation ul li'. Removing the padding makes the menu items to thin and I can't think of any ways to fix it.

Android: When displaying the dropdown menu there are white gaps between the elements in my the dropdown menu and I have no idea where those come from. I have know idea about how Android handles that so I don't know if it's normal or if the code isn't correct.

This is the code: https://jsfiddle.net/5rd2czfL/

HTML

<div id="navigation">
<ul>
    <li><a href="#">MENU L1</a></li>
    <li><a>MENU L2</a>
        <ul>
            <li><a href="#">Sub 1</a></li>
            <li><a href="#">Sub 2</a></li>
        </ul>
    </li>
    <li><a>MENU L3</a>
        <ul>
            <li><a href="#">Very long Sub 1</a></li>
            <li><a href="#">Very long Sub 2</a></li>
            <li><a href="#">Very long Sub 3</a></li>
        </ul>
    </li>
    <li><a href="#">MENU L4</a>
    </li>
    <li><a href="">MENU L5</a></li>

    <li class="menu-right"><a href="'">MENU R1</a></li>
    <li class="menu-right"><a href="#">MENU R2</a></li>
</ul>

CSS

#navigation{
    max-width: 1180px;
    border-top: 1px solid;
    border-bottom: 1px solid;
    color: #0000ff;
    width: 100%;
    color: #000000;
    padding: 10px;
    margin: 5px 0px;
    letter-spacing: 0.1em;
}

#navigation ul{
    padding: 0px;
    margin: 0px;
}

#navigation ul:after {
    clear: both;
    content: " ";
    display: block;
}

#navigation ul li{
    list-style: none;
    float: left;
    padding: 5px 0px;

    -webkit-transition:color 0.2s linear, background 0.2s linear;   
    -moz-transition:color 0.2s linear, background 0.2s linear;  
    -o-transition:color 0.2s linear, background 0.2s linear;    
    transition:color 0.2s linear, background 0.2s linear;
}

#navigation ul li.menu-right{
    float: right;
}

#navigation ul li a{
    text-decoration: none;
    padding: 0px 15px;
    color: #000000;
    cursor: pointer;
}

#navigation ul li ul{
    min-width: 50px;
    position: absolute;
    display: inline;
    visibility: hidden;
    padding-top: 5px;
    z-index: 1;
}

#navigation ul li:hover > ul{
    visibility: visible;
}

#navigation ul li ul li{
    float: none;
}

#navigation ul li:hover, #navigation ul li:hover > ul li{
    color: #ffffff;
    background-color: #555555;
}

#navigation ul li:hover a, #navigation ul li:hover > ul li a{
    color: #ffffff;
}

#navigation ul li ul li:hover{
    background-color: #777777;
}

Answer 1

The problem is, you have absolute positioned elements without mention any position. I have added position:relative to the parent li and supply the proper positions to the child elements like below.

 #navigation ul li{position:relative;}
 #navigation ul li ul{
  min-width: 50px;
  white-space:nowrap;
  position: absolute;
  left:0;
  top:20px;
  display: inline;
  visibility: hidden;
  padding-top: 5px;
  z-index: 1;
}

DEMO