styles.css

* {
  box-sizing: border-box;
  font-family: Verdana, sans-serif;
}

html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
  width: 100%;
}

div#app {
  width: 100%;
  height: 100%;
}

div#app div#login {
  align-items: center;
  background-color: #e2e2e5;
  display: flex;
  justify-content: center;
  width: 100%;
  height: 100%;
}

div#app div#login div#description {
  background-color: #ffffff;
  width: 280px;
  padding: 35px;
}

div#app div#login div#description h1,
div#app div#login div#description p {
  margin: 0;
}

div#app div#login div#description p {
  font-size: 0.8em;
  color: #95a5a6;
  margin-top: 10px;
}

div#app div#login div#form {
  background-color: #34495e;
  border-radius: 5px;
  box-shadow: 0px 0px 30px 0px #666;
  color: #ecf0f1;
  width: 260px;
  padding: 35px;
}

div#app div#login div#form label,
div#app div#login div#form input {
  outline: none;
  width: 100%;
}

div#app div#login div#form label {
  color: #95a5a6;
  font-size: 0.8em;
}

div#app div#login div#form input {
  background-color: transparent;
  border: none;
  color: #ecf0f1;
  font-size: 1em;
  margin-bottom: 20px;
}

div#app div#login div#form ::placeholder {
  color: #ecf0f1;
  opacity: 1;
}

div#app div#login div#form button {
  background-color: #ffffff;
  cursor: pointer;
  border: none;
  padding: 10px;
  transition: background-color 0.2s ease-in-out;
  width: 100%;
}

div#app div#login div#form button:hover {
  background-color: #eeeeee;
}

@media screen and (max-width: 600px) {
  div#app div#login {
    align-items: unset;
    background-color: unset;
    display: unset;
    justify-content: unset;
  }

  div#app div#login div#description {
    margin: 0 auto;
    max-width: 350px;
    width: 100%;
  }

  div#app div#login div#form {
    border-radius: unset;
    box-shadow: unset;
    width: 100%;
  }

  div#app div#login div#form form {
    margin: 0 auto;
    max-width: 280px;
    width: 100%;
  }
}