style.css

@import url('https://fonts.googleapis.com/css?family=Nunito:400,700&display=swap');
* {
  margin: 0;
  padding: 0;
}

body {
  height: 100vh;
  padding: 20px;
  background: #fdfdfd;
  font-family: 'Nunito', sans-serif;
  font-size: 1rem;
  margin: 0;
  padding: 0;
}

main {
  height: 95%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  padding: 10px;
}

img {
  height: 20vh;
  padding: 10px;
}

h3 {
  color: #009846;
}

#phone,
.btn {
  padding-top: 6px;
  padding-bottom: 6px;
  border: 1px solid #ccc;
  border-radius: 4px;
}

.btn {
  color: #ffffff;
  background-color: #009846;
  border-color: #009846;
  font-size: 14px;
  outline: none;
  cursor: pointer;
  padding-left: 12px;
  padding-right: 12px;
}

.btn:focus,
.btn:hover {
  background-color: #007b3a;
  border-color: #007b3a;
}

.btn:active {
  box-shadow: inset 0 3px 5px rgba(0, 0, 0, 0.125);
}

.alert {
  padding: 15px;
  margin-top: 10px;
  border: 1px solid transparent;
  border-radius: 4px;
}

.alert-error {
  color: #a94442;
  background-color: #f2dede;
  border-color: #ebccd1;
}

.footer {
  text-align: center;
  font-size: small;
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
}