index.css

body {
	font: 24px/30px 'Noto Sans CJK KR', Noto Sans KR, sans-serif
    
}

.main-background{
  background-image: linear-gradient( rgba(76, 76,76 , 0.6), rgba(76, 76, 76, 0.6) ), url("images/4472650.png");
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
  width: 100%;
  height: 100%;
  position: absolute;
}

.main-logo{
  position: absolute;
  z-index:1;
  float:left;
  width:100px;
  height: 100px;
  margin-top:20px;
  margin-left: 40px;
}

a{text-decoration:none; color:#000000;}         
         a:hover{color:#ff0000;}                    
         
         /* nav tag */
         nav ul{padding-top:10px;}                     /*  상단 여백 10px  */
         nav ul li {
            display:inline;                         /*  세로나열을 가로나열로 변경 */
            border-left:1px solid #999;             /* 각 메뉴의 왼쪽에 "|" 표시(분류 표시) */
   
            padding:0 10px;                         /* 각 메뉴 간격 */
        }
         nav ul li:first-child{border-left:none;}   

nav{
  position: absolute;
  z-index:1;
  height: 50px;
  padding: 20px;;
  margin:0;
  margin-left:100px;
}

nav a:link, nav a:visited{
  font-family: 'Montserrat', sans-serif;
  font-size: 1.3rem;
  font-weight: 600;
  color:#fff;
  text-decoration: none;
  text-align: center;
}

.main_text{
    position: absolute;
    z-index: 2;
    top:40%;
    left:10%;
    font-family: 'Open Sans', sans-serif;
    font-size: 50px;
    color:#fff;
}

button{
  top:48%;
  width:150px;
  height: 40px;
  color:#000;
  background: rgba(255, 255, 255, 0.7);
  font-size: 20px;
  font-weight: 800;
  border:none;
  border-radius: 20px;
  box-shadow: 0 4px 16px rgba(22, 22, 22, 0.3);
  transition:0.3s;
  position: absolute;
  left:15%;

  transform: translate(-50%,-50%);
}
button:focus {
  outline:0;

}
button:hover{
  background: rgba(0,79,255,0.9);
  cursor: pointer;
  box-shadow: 0 2px 4px rgba(0,79,255,0.6);
}

.label-container{
    position: absolute;
    z-index:2;
    top:52%;
    left:10%;
    color: #fff;
    font-weight: 600;
    font-size: 50px;
}

.square{
  position: absolute;
  z-index: 1;
  top: 130px;
  left: 50%;
  width: 750px;
  height: 750px;
  background: rgba(225, 225, 225, 0.8);
}

.webcam-container{

    margin-top: 150px;
    margin-left: 50%;
    position: relative;
    z-index: 2;
    float:right;
    right:10%;
}