:root {
  --red-color: #ea4f3e;
}

* {
  box-sizing: border-box;
}

body {
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;

  width: 100vw;
  height: 100vh;
  margin: 0;

  display: flex;
  flex-direction: column;
  align-items: center;

  color: #495057;
}

h1 {
  font-family: cursive;
  font-size: 3em;

  margin-top: 20%;
}

label {
  display: inline-block;
  margin-bottom: 0.5em;
}

input {
  display: block;
  width: 70vw;
  padding: 0.37em 0.7em;

  font-size: 1em;
  line-height: 1.5;

  outline: none;

  border: 1px solid #ced4da;
  border-radius: 0.25em;
}

input.invalid {
  border: 1px solid var(--red-color);
}

small {
  color: var(--red-color);
}

button {
  color: #ffffff;
  background-color: var(--red-color);
  font-size: 1rem;

  padding: 0.37em 0.7em;
  border-radius: 0.25em;
  line-height: 1.5;
}

.input-group {
  margin-bottom: 1.5em;
}

.success {
  font-size: 1.5em;
  margin-top: 50%;
}