.first-level li:hover > ul
используется> вместо .first-level li:hover ul
..first-level li:hover ul
это выберет все ul
внутри .first-level
.first-level li:hover > ul
выберет все ul
элементы, где родительский элемент .first-level
ниже - это ссылка, которая поможет вам понять селекторы css,Надеюсь это поможет.спасибо.
https://www.w3schools.com/cssref/css_selectors.asp
@font-face {
font-family: 'Space Mono';
font-style: normal;
font-weight: 400;
src: url('space-mono-v4-latin-regular.eot');
src: local('Space Mono'), local('SpaceMono-Regular'),
url('space-mono-v4-latin-regular.eot?#iefix') format('embedded-opentype'),
url('space-mono-v4-latin-regular.woff2') format('woff2'),
url('space-mono-v4-latin-regular.woff') format('woff'),
url('space-mono-v4-latin-regular.ttf') format('truetype'),
url('fonts/space-mono-v4-latin-regular.svg#SpaceMono') format('svg');
}
body {
margin: 0;
padding: 0;
font-family: 'Space Mono', monospace;
background: #000;
background: url(Galaxy.jpg);
background-size: cover;
}
h2 {
font-size: 3em;
margin: 150px 0px 0px 120px;
padding: 0px 0px 30px;
color: #fff;
}
p {
font-size: 1.2em;
margin: 0px 0px 0px 120px;
padding: 20px 0px 20px 50px;
color: #fff;
text-indent: 50px;
width: 720px;
word-wrap: break-word;
border-left: 4px solid #fff;
}
.first-level {
font-size: 24px;
list-style: none;
text-align: center;
padding: 0px 0px 0px 0px;
margin: -60px 0px 0px 0px;
position: sticky;
top: 10px;
display: flex;
justify-content: center;
}
.first-level a {
text-decoration: none;
line-height: 60px;
color: #fff;
}
.first-level li {
position: relative;
text-align: center;
height: 60px;
width: 200px;
background: rgba(0,0,0,0.5);
}
.first-level li:hover {
background-color: teal;
}
.first-level li:hover > ul {
display: inline;
}
.second-level {
position: absolute;
display: none;
top: 60px;
left: 0;
width: 200px;
list-style: none;
padding: 0px 0px 0px 0px;
margin: 0px 0px 0px 0px;
}
.second-level li {
position: relative;
height: 60px;
background: rgba(0,0,0,0.6);
}
.second-level li:hover {
background: teal;
}
.third-level {
position: absolute;
display: none;
top: 0px;
right: -200px;
width: 200px;
list-style: none;
padding: 0px 0px 0px 0px;
margin: 0px 0px 0px 0px;
}
.third-level li {
position: relative;
height: 60px;
background: rgba(0,0,0,0.6);
}
.third-level li:hover {
background: teal;
}
<!DOCTYPE html>
<html>
<head>
<title>NavigationBar</title>
<link rel="stylesheet" href="newnavbar.css" type="text/css">
</head>
<body>
<ul class ="first-level">
<li><a href="#">HOME</a></li>
<li><a href="#">LAB 1-5</a>
<ul class ="second-level">
<li><a href ="#">LAB 1</a>
<ul class ="third-level">
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
</ul>
</li>
<li><a href ="#">LAB 2</a>
<ul class ="third-level">
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
</ul>
</li>
<li><a href ="#">LAB 4</a>
<ul class ="third-level">
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
</ul>
</li>
<li><a href ="#">LAB 5</a>
<ul class ="third-level">
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#">LAB 6-8</a>
<ul class ="second-level">
<li><a href ="#">LAB 6</a>
<ul class ="third-level">
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
</ul>
</li>
<li><a href ="#">LAB 7</a>
<ul class ="third-level">
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
</ul>
</li>
<li><a href ="#">LAB 8</a>
<ul class ="third-level">
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
</ul>
</li>
</ul>
<li><a href="#">LAB 9-11</a>
<ul class ="second-level">
<li><a href ="#">LAB 9</a>
<ul class ="third-level">
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
</ul>
</li>
<li><a href ="#">LAB 10</a>
<ul class ="third-level">
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
</ul>
</li>
<li><a href ="#">LAB 11</a>
<ul class ="third-level">
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
</ul>
</li>
</ul>
<li><a href="#">LAB 12-14</a>
<ul class ="second-level">
<li><a href ="#">LAB 12</a>
<ul class ="third-level">
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
</ul>
</li>
<li><a href ="#">LAB 13</a>
<ul class ="third-level">
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
</ul>
</li>
<li><a href ="#">LAB 14</a>
<ul class ="third-level">
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
<li><a href ="#">Content</a></li>
</ul>
</li>
</ul>
</ul>
<h2>CSC 212 - Spring 2019.</h2>
<p>This site represents work that I have done in support of my
efforts to learn to program in the CS1 course at SUNY Oswego
during the Spirng 2019 semester. The materials will be temporally
organized for the most part. Links to external sites that pertain
to computer programming, problem solving, Java, Web development,
and related matters will be placed after the personally created
artifacts.</p>
</body>
</html>