仅在单击父级后打开子菜单

我认为我的问题以前已经被多次回答，但我找不到我的情况 .

我有一个带子菜单的垂直菜单，我想只显示父菜单被点击（没有悬停），一次只显示一个子菜单，然后点击菜单后的某个地方，我想要显示子菜单，我希望子菜单消失 .

这就是我现在所拥有的 - 它现在基于徘徊 . 我试图改变一个：悬停到类似：活动的东西，但它不能很好地工作（我在CSS中不是很好） .

/* The container */
     #cssmenu  > ul {
        display: block;
        position: relative;
      //width: 190px;
      width:100%;
     }

        /* The list elements which contain the links */
           #cssmenu  > ul li {
              display: block;
              position: relative;
              margin: 0;
              padding: 0;
              width: 100%;  
           }

            /* General link styling */
            #cssmenu  > ul li a {
                display: block;
                position: relative;
                margin: 2;
                width:95%; 
                height:50px; 
                background-color:#ABC578; 
                border-left:solid 0px #FFFFFF; 
                border-bottom:solid 1px #FFFFFF;
                font: 0.7em Tahoma, sans-serif;
                font-size: 14px;
                font-weight:bold;
                color: #FFFFFF;
                text-decoration:none;
                padding-top:30px;
            }


            /* The hover state of the menu/submenu links */
            #cssmenu  > ul li>a:hover, #cssmenu  > ul li:hover>a {
                color: #fff;
                text-shadow: 0 1px 0 rgba(0, 0, 0, .3);
                background: #82c500;
                background: -webkit-linear-gradient(bottom, #82c500, #000000);
                background: -ms-linear-gradient(bottom, #82c500, #000000); 
                background: -moz-linear-gradient(bottom, #82c500, #000000);
                background: -o-linear-gradient(bottom, #82c500, #000000);
                border-color: transparent;
            }

            /* The arrow indicating a submenu */
            #cssmenu  > ul .has-sub>a::after {
                content: '';
                position: absolute;
                top: 34px;
                right: 8px;
                width: 0px;
                height: 0px;

                /* Creating the arrow using borders */
                border: 4px solid transparent;
                border-left: 4px solid #d8d8d8; 
            }

            /* The same arrow, but with a darker color, to create the shadow effect */
            #cssmenu  > ul .has-sub>a::before {
                content: '';
                position: absolute;
                top: 35px;
                right: 8px;
                width: 0px;
                height: 0px;

                /* Creating the arrow using borders */
                border: 4px solid transparent;
                border-left: 4px solid #000;
            }

            /* Changing the color of the arrow on hover */
            #cssmenu  > ul li>a:hover::after, #cssmenu  > ul li:hover>a::after {
                border-left: 4px solid #fff;
            }

            #cssmenu  > ul li>a:hover::before, #cssmenu  > ul li:hover>a::before {
                border-left: 4px solid rgba(0, 0, 0, .3);
            }


            /* THE SUBMENUS */
            #cssmenu  > ul ul {
                position: absolute;
                left:95%;
                width:100%;
                top: -9999px;
                padding-left: 5px;
                opacity: 0;
                /* The fade effect, created using an opacity transition */
                -webkit-transition: opacity .2s ease-in;
                -moz-transition: opacity .2s ease-in;
                -o-transition: opacity .2s ease-in;
                -ms-transition: opacity .2s ease-in;
            }

            /* Showing the submenu when the user is hovering the parent link */
            #cssmenu  > ul li:hover>ul {
                top: -2px;
                opacity: 1;
            }

有人有想法吗？