Edit in JSFiddle

/*
Techonolgy Quest;

creating a horizontal Dropline menu is simple.
Following id will define the dimensions for the menu, margin, padding width, height.
For the drop line menu the position is added in this class.
Its not necessary to add position
*/
 #menucontainer {
    margin: 0px;
    padding: 0px;
    width: 100%;
    height: 100px;
    position;
    relative;
}
#menucontainer ul {
    margin: 0px;
    padding: 0px;
    list-style: none;
    width: 600px;
    height:40px;
}
/* Following selector will define the style for individual parent menu. The following style gives them a look when the menus are not selected.
note that the position proerty is not set.
*/
 #menucontainer ul li.parent_menu {
    list-style: none;
    margin: 0px;
    padding: 10px;
    background-color:#69A9B1;
    display: inline;
    width: 100%;
    height: 100%;
    border-right: 3px solid #6A91A8;
}
/* 
Style for the anchor tag defined in the parent. 
*/
 #menucontainer ul li.parent_menu a {
    margin-left: 10px;
    padding-left: 10px;
    margin-right: 10px;
    padding-right: 10px;
    background-color:transparent;
    display: inline;
    text-decoration: none;
    font-family:"Times New Roman", "Arabic";
    font-size: 20px;
    color: #E3E3C0;
    line-height: 50px;
}
/* The hover effect is defined using the below selectors
For the background-color opacity is used to create a semi-transperant look as a hover effect
*/
 #menucontainer ul li.parent_menu:hover {
    list-style: none;
    margin: 0px;
    padding: 10px;
    opacity: 0.8;
    background-color:#69A9B1;
    display: inline;
    border-right:3px solid #6A91A8;
}
/*
The following class will define the style for anchor tag in the 

*/
 #menucontainer ul li.parent_menu:hover a {
    list-style: none;
    margin-left: 10px;
    padding-left: 10px;
    margin-right: 10px;
    padding-right: 10px;
    background-color:transparent;
    display: inline;
    text-decoration: none;
    font-family:"Times New Roman", "Arabic";
    font-size: 20px;
    color:black;
    line-height: 33px;
}
/***************SUB MENU***********************/

/*
Following class will hide the sub menu when the mouse is not hovering.
*/
 #menucontainer ul li.parent_menu ul {
    margin: 0px;
    padding: 0px;
    list-style: none;
    display:none;
    position: absolute;
    height: 0;
}
/*
Following class display hide the sub menu when the mouse is not hovering.
Note: for this style of the menu position is set to 'absolute'

*/
 #menucontainer ul li.parent_menu:hover ul {
    margin: -5px 0 0 0;
    padding: 0px;
    list-style: none;
    display:block;
    position: absolute;
    height: auto;
    width:100%;
    background-color:#69A9B1;
}
/* Following selector will define the style for individual sub menu. The following style gives them a look when the menus are not selected.
note that the position proerty is not set and dispaly is block.
Also the float property is set left; This will keep the menu in a single line.
*/
 #menucontainer ul li.parent_menu:hover ul li.child_menu {
    list-style: none;
    margin-left: 10px;
    padding-left: 10px;
    margin-right: 10px;
    padding-right: 10px;
    display: block;
    float: left;
}
/*
Following class will define the style for the anchor tag of the submenu/child menu
*/
 #menucontainer ul li.parent_menu:hover li.child_menu a {
    padding-left: 10px;
    margin-right: 10px;
    padding-right: 10px;
    background-color:transparent;
    display: inline;
    text-decoration: none;
    font-family:"Times New Roman", "Arabic";
    font-size: 20px;
    color: #E3E3C0;
    line-height: 33px;
}
#menucontainer ul li.parent_menu:hover li.child_menu a:hover {
    margin-left: 10px;
    padding-left: 10px;
    margin-right: 10px;
    padding-right: 10px;
    background-color:transparent;
    display: inline;
    text-decoration: none;
    font-family:"Times New Roman", "Arabic";
    font-size: 20px;
    color: #FFFFFF;
    line-height: 33px;
}