body {
  width: 100%;
  top: 0;
  margin: 0;
  padding: 0;
  font-family: sans-serif;
  background-image: url("./img/index.jpg");
  background-repeat: no-repeat;
}

#logo {
  max-width: 200px;
  height: auto;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

ul {
  margin-top: 0;
  list-style-type: none;
  text-align: center;
  position: relative;
}

li {
  display: inline;
  margin: 0 20px 0 0;
}

a {
  margin-top : 35px;
  text-decoration: none;
  color: white;
  font-size: large;
  font-weight: bold;
  display: inline-block;
}

.gnb {
  text-align: center;
  background-color: rgb(0,0,0,0.5);
  height: 100px;
}

.gnb a {
  letter-spacing: 0;
  transition: 0.35s;
}

.gnb a:hover, .gnb a:active {
  letter-spacing: 5px;
  transition: 0.35s;
}

.gnb a:after {
  bottom: -10px;
}

.gnb a:before {
  top: -10px;
}

.gnb a:after, .gnb a:before {
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
  border: 1px solid rgba(255, 255, 255, 0);
  content: "";
  margin: 0 auto;
  display: block;
  transition: all 280ms ease-in-out;
  width: 0;
}

.gnb a:hover:after, .gnb a:hover:before {
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
  border-color: #fff;
  transition: width 350ms ease-in-out;
  width: 100%;
}

.gnb a:hover:before {
  width: 100%;
}

.btn {
  width: 70px;
  height: 25px;
  font-size: 10px;
  letter-spacing: 2.5px;
  font-weight: 500;
  color: #000;
  background-color: #fff;
  border: none;
  border-radius: 45px;
  box-shadow: 0px 8px 15px rgba(0, 0, 0, 0.1);
  transition: all 0.3s ease 0s;
  cursor: pointer;
  outline: none;
}

#login:hover, #myPage:hover {
  background-color: #2EE59D;
  box-shadow: 0px 15px 20px rgba(46, 229, 157, 0.4);
  color: #fff;
  transform: translateY(-7px);
}

#sign_up:hover, #logout:hover {
  background-color: #ffb0e1;
  box-shadow: 0px 15px 20px rgba(255, 176, 225, 0.4);
  color: #fff;
  transform: translateY(-7px);
}

input {
  position: absolute;
}

#nim {
  color: white;
  font-size: 82%;
  position: fixed;
  margin-top: 42px;
  margin-left: 16%;
}

#login, #myPage {
margin-top: 38px;
margin-left: 20%;
}
#sign_up, #logout {
margin-top: 38px;
margin-left: 25%;
}