JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.14/angular.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.3.15/angular-animate.min.js"></script>
<div ng-app="myapp">
    <div ng-controller="showCrtl">
        <div class="top" ng-mouseover="menu()" ng-mouseout="menu()">Mouse over me</div>
        <div ng-hide="bottom" ng-mouseover="menu()" ng-mouseout="menu()" class="bottom"></div>
    </div>
</div>

CSS

.top {
    background-color: blue;
    width: 100%;
    height: 150px;
}
.bottom {
    background-color: red;
    width: 50%;
    margin-left: 25%;
    height: 300px;
}
.bottom {
    -webkit-transition: all 2s ease;
    /* Safari */
    transition: all 2s ease;
}
.bottom.ng-hide {
    opacity:0;
}

JavaScript

angular.module("myapp", ["ngAnimate"])

 .controller("showCrtl", function ($scope) {
    $scope.bottom = true;

    $scope.menu = function () {
        if ($scope.bottom) {
            $scope.bottom = false;
        } else {
            $scope.bottom = true;
        }
    };
});