@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+KR&display=swap');

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Noto Sans KR', sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
}

.login-form {
  width: 90%;
  max-width: 400px;
}

.login-form h1 {
  font-size: 32px;
  text-align: center;
  margin-bottom: 50px;
}

.int-area {
  width: 100%;
  position: relative;
  margin-top: 20px;
}

.int-area:first-child {
  margin-top: 0;
}

.int-area input {
  width: 100%;
  padding: 20px 10px 10px;
  background-color: transparent;
  border: none;
  border-bottom: 1px solid black;
  font-size: 18px;
  outline: none;
}

.int-area label {
  position: absolute;
  left: 10px;
  top: 15px;
  font-size: 18px;
  transition: top 0.5s ease;
}

.int-area label.warning {
  color: red !important;
  animation: warning 0.3s ease;
  animation-iteration-count: 3;
}

@keyframes warning {
  0% {
    transform: translateX(-8px);
  }
  25% {
    transform: translateX(8px);
  }
  50% {
    transform: translateX(-8px);
  }
  75% {
    transform: translateX(8px);
  }
}

.int-area input:focus + label,
.int-area input:valid + label {
  top: -2px;
  font-size: 13px;
  color: #166caa;
}

.btn-area {
  margin-top: 30px;
}

.btn-area button {
  width: 90%;
  height: 50px;
  margin: 0 auto;
  display: block;
  color: #fff;
  background: #166caa;
  border: none;
  border-radius: 20px;
  font-size: 20px;
  cursor: pointer;
}

.caption {
  margin-top: 20px;
  text-align: center;
}

.caption a {
  margin: 0 20px;
  font-size: 15px;
  color: blue;
  text-decoration: none;
}

@media (max-width: 600px) {
  .login-form h1 {
    font-size: 28px;
  }
  .btn-area button {
    width: 100%;
    font-size: 18px;
  }
}