#MainMenu {
  position: relative;
  z-index: +1;
}

#MainMenu ul>li {
    padding: 0 !important;
}

#MainMenu li {
  position: relative;
}

#MainMenu ul>li>a {
  padding: 10px;
}

#MainMenu ul {
  position: absolute;
  left:-99999px;
}

#MainMenu li:hover ul{
  left:0;
  min-width: 100%;
}

#MainMenu li:hover ul, #MainMenu li:hover, #MainMenu ul>li>a {
  background: rgb(240,240,240);
}