style.css

*,
*:before, *:after {
  box-sizing: border-box;
}

body {
  background-color: rgb(247,247,247);
  color: rgb(51,51,51);
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 100%;
  margin: 0;
  padding: 0;
}

.main-wrapper,
.page-footer {
  line-height: 1.4;
  margin: 3rem auto;
  max-width: 680px;
  width: 90%;
}

.main-wrapper {
  font-size: 1.4rem;
}

h1 {
  font-size: 2em;
  line-height: 1;
}

a,
a:visited {
  color: rgb(229,23,23);
  transition: color 0.2s ease-out;
}

a:hover,
a:focus {
  color: rgb(153,0,0);
}

p.additional {
  font-size: 0.7em;
}

.main-form {
  background-color: #ccc;
  border-radius: 3px;
  border: 1px solid;
  padding: 1em 5%;
  width: 100%;
}

label {
  line-height: 1;
  display: block;
}

input,
a.download {
  border: 1px solid;
  border-radius: 3px;
  display: block;
  font-family: inherit;
  font-size: inherit;
  padding: 0.25rem 1.5%;
  margin: 0;
  outline: none;
  -moz-appearance: none;
  -webkit-appearance: none;
  transition: color 0.2s ease-out, border-color 0.2s ease-out, background-color 0.2s ease-out, box-shadow 0.2s ease-out;
}

input[type="url"] {
  background-color: rgb(247,247,247);
  margin-top: 0.6rem;
  width: 100%;
}

input[type="url"]:focus {
  background-color: rgb(255,255,255);
  border-color: rgb(229,23,23);
  box-shadow: 0 0 0.3125rem rgba(229,23,23,0.5);
  color: rgb(229,23,23);
}

.btn,
a.btn:visited {
  background-color: rgb(229,23,23);
  border: 1px solid rgb(229,23,23);
  color: rgb(247,247,247);
  margin-top: 0.7rem;
  padding: 0.25rem 5%;
  text-align: center;
  text-decoration: none;
}

.btn:hover,
.btn:focus,
a.btn:visited:hover,
a.btn:visited:focus {
  border-color: rgb(153,0,0);
  background-color: rgb(153,0,0);
  color: rgb(255,255,255);
}

img {
  height: auto;
  width: 100%;
}