* {
  margin: 0;
}

html,
body {
  min-height: 100vh;
}

body {
  background: #222;
  color: #fff;
  font-family: Helvetica, Arial, sans-serif;
}

.text-success {
  color: #3a4;
}

.text-fail {
  color: #e34;
}

.back {
    height: 100vh;
    display: box;
    display: flex;
    justify-content: center;
    align-items: center;
}

.main-block {
    box-sizing: border-box;
    padding: 30px;
    border: 1px solid #999;
    border-radius: 15px;
    transition: all 0.4s;
}

.main-block:focus-within, .main-block:hover {
    border-color: #bbb;
}

.heading {
    display: box;
    display: flex;
    justify-content: center;
    padding-bottom: 20px;
    font-size: 20px;
    transition: 0.4s;
    color: #ccc;
}

.heading:hover {
    color: #fff;
}

.form-auth {
    display: box;
    display: flex;
    flex-direction: column;
    letter-spacing: 1px;
}

.form-auth-input {
    position: relative;
    width: 240px;
    height: 40px;
    margin: 8px 0;
    background: transparent;
    color: #ddd;
    box-sizing: border-box;
    font-size: 16px;
    outline: none;
    border-top: none;
    border-bottom: none;
    border-left: none;
    border-right: none;
    box-shadow: 0 1px 0 0 #777;
    transition: all .4s;
}

.form-auth-input:focus {
    box-shadow: 0 1.5px 0 0 #aaa;
}

.form-auth-input::placeholder {
    color: #ccc;
    transition: inherit;
}

.form-auth-input:focus::placeholder {
    color: transparent;
}

.form-auth-submit {
  font-family: inherit;
  font-size: inherit;
  letter-spacing: inherit;
  cursor: pointer;
  border: 1px solid #ddd;
  height: 50px;
  border-radius: 10px;
  background: transparent;
  color: #ddd;
  outline: none;
  margin-top: 20px;
  transition: all 0.4s;
}
.form-auth-submit:hover {
  background: #fff;
  border: 1px solid #fff;
  color: #222;
}