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

html {
  font-family: Arial, Helvetica, sans-serif;
}

input {
  font-family: Arial, Helvetica, sans-serif;
  font-size: inherit;
}

input:focus-visible {
  outline: none;
  border: none;
}
/* end: common */
.input-box {
  width: 100px;
  margin: 80px auto;
  position: relative;
}

.input-box input {
  padding: 8px;
  border: 2px solid gray;
  border-radius: 4px;
  color: #333;
  font-size: 16px;
}

.input-box input:focus {
  border: 2px solid purple;
}

.input-box input:focus + label {
  top: -8px;
  padding-inline: 2px;
  background: #fff;
  color: purple;
}

.input-box input:not(:placeholder-shown) + label {
  top: -8px;
  padding-inline: 2px;
  background: #fff;
}

.input-box label {
  position: absolute;
  top: 11px;
  left: 8px;
  transition: top 0.4s ease;
  font-size: 12px;
  color: gray;
  cursor: text;
}