:root{
background-color: #2a5c99;
}
h1{
color: gold;
text-shadow: -1px 0 black, 0 1px black, 1px 0 black, 0 -1px black;
margin: auto;
   -moz-user-select: none;
   -khtml-user-select: none;
   -webkit-user-select: none;

   /*
     Introduced in Internet Explorer 10.
     See http://ie.microsoft.com/testdrive/HTML5/msUserSelect/
   */
   -ms-user-select: none;
   user-select: none;
}
.color{
width: 20vw;
height: 20vw;
background-color: black;
margin: 2.5vw;
color: white;
display: flex;
  align-items: center;
  justify-content: center;
  font-size: 4vw;
  border-radius: 25px;
     -moz-user-select: none;
   -khtml-user-select: none;
   -webkit-user-select: none;

   /*
     Introduced in Internet Explorer 10.
     See http://ie.microsoft.com/testdrive/HTML5/msUserSelect/
   */
   -ms-user-select: none;
   user-select: none;
}
#green{background-color: green;}
#red{background-color: red;}
#blue{background-color: blue;}
#yellow{background-color: yellow; color: gray}
#color_box{
display: flex;
}
#target{
background-color: black;
width: calc(100vh - 60vw)
margin: 10vw;
height: calc(100vh - 60vw);
  border: 10px solid white;
  padding: 10px;
  border-radius: 25px;
}