body {
    background: linear-gradient(skyblue,green);
   border:1000px;
 }
 h1 {
   color:blueviolet;
   text-align:center;
   text-decoration:underline;
 }
 h2 {
   color:lightgreen;
   text-decoration:underline
 }
 mark{
   background-color: blue;
   color: white;
 }
 
 
 img{
   border-width:15px 10px;
 }
 span{
     margin-right: 25px;
 }
 header img{
    width: 200px;
    display:block;
    position: relative;
}
header button{
    background-color: black;
    padding:10px
}
header a{
    color: white;
    text-decoration: none;
    font-size: larger;
}
span{
    margin-right: 25px;
}
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}


header {
    background-color: #333;
    color: #fff;
    text-align: center;
    padding: 1rem;
}


header a {
    color: #fff;
    text-decoration: none;
    margin-right: 1rem;
}


hr {
    border: none;
    border-top: 1px solid #ddd;
    margin: 1rem 0;
}

.dropbtn {
  background:transparent;
  color: white;
  padding: 16px;
  font-size: 16px;
  border: none;
  cursor: pointer;
}

.dropdown {
  position: relative;
  display: inline-block;
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color:#123456;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  z-index: 1;
}

.dropdown-content a {
  color: white;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}

.dropdown:hover .dropdown-content {
  display: block;
}

.dropdown:hover .dropbtn {
  background-color:#8A2BE2;
}