Edit in JSFiddle

/*
Techonolgy Quest;
creating a Circular menu is simple and completely depends on the 
"border-radius".
While creating circular menu always keep same value for height, width and border-radius.

Following id will define the dimensions for the menu, margin, padding width, height.
*/
 #menucontainer {
    margin: 0px;
    padding: 0px;
    width: 100%;
    height: 90px;
}
/* Following selectors will define the color and the border radius for the menu*/
 #menucontainer ul, #menucontainer ul li ul {
    list-style: none;
    margin: 0px;
    padding: 0px;
}
/* Following selector will define the style for individual menu or li tags. The following style gives them a look when the menus are not selected.
note that the position proerty is set to relative and dispaly is inline.
*/
 #menucontainer ul li {
    list-style: none;
    margin: 10px;
    padding: 0px;
    background-color:#2CDF7B;
    position: relative;
    display: inline;
    text-align: center;
    /*Setting the height and width for the menu*/
    width: 90px;
    cursor:pointer;
    height: 90px;
    /*Setting the border-radius for the menu
    various prefix are added so it is supported in older version of
    browsers. For IE supported from IE-9+
    IMPORTANT: to keep the border radius height and width same to get circle.
    */
    -moz-border-radius: 90px;
    -webkit-border-radius: 90px;
    -khtml-border-radius: 90px;
    border-radius: 90px;
    /*Adding the box shadow to the menu*/
    box-shadow: 0 0 10px black;
    -moz-box-shadow: 0 0 10px black;
    -webkit-box-shadow: 0 0 10px black;
    float: left;

}
/* Style for the anchor tag defined in the menu. 
*/
 #menucontainer ul li a {
    margin: 10px;
    padding: 10px;
    background-color:transparent;
    display: block;
    text-decoration: none;
    text-align: center;
    font-family:"Times New Roman", "Arabic";
    font-size: 18px;
    height: 20px;
    color: #E3E3C0;
}
/* The hover effect is defined using the below selectors
For the opacity is used to create a semi-transperant look as a hover effect
*/
 #menucontainer ul li:hover {
    list-style: none;
    margin: 10px;
    padding: 0px;
    opacity: 0.7;
    background-color:#2CDF7B;
    position: relative;
    display: block;
    width: 90px;
    text-align: center;
    cursor:pointer;
    height: 90px;
    /*Setting the border-radius for the menu
    various prefix are added so it is supported in older version of
    browsers. For IE supported from IE-9+
    IMPORTANT: to keep the border radius height and width same to get circle.
    */
    -moz-border-radius: 90px;
    -webkit-border-radius: 90px;
    -khtml-border-radius: 90px;
    border-radius: 90px;
    -moz-box-shadow: inset 0 0 10px black;
    box-shadow: inset 0 0 10px black;
    -webkit-box-shadow: inset 0 0 10px black;
}
#menucontainer ul li:hover a {
    margin: 10px;
    padding: 10px;
    background-color:transparent;
    display: block;
    text-decoration: none;
    text-align: center;
    font-family:"Times New Roman", "Arabic";
    font-size: 18px;
   width: 65%;
    height: 65%;
    color: white;
}
/*******************************************************/
 
/*******************************************************/

/*Sub menu*/

/*******************************************************/
 #menucontainer ul li > ul {
    display : none;
    overflow: hidden;
    position: relative;
    border-bottom: solid 1px;
    border: 0px;
    height: 0px;
    width: 100%;
}
#menucontainer ul li:hover >  ul {
    z-index: 10;
    
    
    float: none;
    top: -7px;
    left: -15px;
    margin: 9px;
    height: auto;
    padding: 0px 5px 0px 0px;
    display:block;
    width: 100px;
    
}
#menucontainer ul li:hover > ul li, #menucontainer ul li a:hover > ul li {
list-style: none;
    margin: 10px;
    
    padding: 0px;
    background-color:#2CDF00;
    position: relative;
    display: inline;
    text-align: center;
    /*Setting the height and width for the menu*/
    width: 90px;
    cursor:pointer;
    height: 90px;
    /*Setting the border-radius for the menu
    various prefix are added so it is supported in older version of
    browsers. For IE supported from IE-9+
    IMPORTANT: to keep the border radius height and width same to get circle.
    */
    -moz-border-radius: 90px;
    -webkit-border-radius: 90px;
    -khtml-border-radius: 90px;
    border-radius: 90px;
    /*Adding the box shadow to the menu*/
    box-shadow: 0 0 10px black;
    -moz-box-shadow: 0 0 10px black;
    -webkit-box-shadow: 0 0 10px black;
    float: left;
}

/*******************************************************/
 #menucontainer ul li:hover > ul li:after, #menucontainer ul li a:hover > ul li:after {
    content:" ";
    border: solid transparent;
    margin: 0px;
    padding: 0px;
    position: absolute;
    pointer-events: none;
    border-color: rgba(44, 223, 123, 0);
    border-top-color: #2CDF00;
    top: 98%;
    left: 50%;
    margin-left: -10px;
    border-width:10px;
}


 #menucontainer ul li:hover > ul li:before, #menucontainer ul li a:hover > ul li:before {
    content:" ";
    border: solid transparent;
    margin: 0px;
    padding: 0px;
    position: absolute;
    pointer-events: none;
    border-color: rgba(44, 223, 123, 0);
    border-bottom-color: #2CDF00;
    bottom: 98%;
    left: 50%;
    margin-left: -10px;
    border-width:10px;
}
/*******************************************************/