style.css

* {
  margin: 0;
  padding: 0;
}
html {
  overflow: hidden;
}
a, a:visited {
  outline: none;
  color: #389dc1;
}
a:hover {
  text-decoration: none;
}
section, footer, header, aside {
  display: block;
}

/* The main page elements */

body {
  font: 15px/1.3 'Raleway', sans-serif;
  color: #fff;
  width: 100%;
  height: 100%;
  position: absolute;
  overflow: hidden;
}
#stage {
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  left: 0;
  transition: top 0.4s;
}
#stage > div {
  /* The step divs */
  height: 100%;
  position: relative;
}
#stage h1 {
  font-weight: normal;
  font-size: 48px;
  text-align: center;
  color: #fff;
  margin-bottom: 60px;
}
#stage h2 {
  font-weight: normal;
  font-size: 14px;
  font-family: Arial, Helvetica, sans-serif;
  margin: -40px 0 45px;
  font-style: italic;
}
.content {
  position: absolute;
  text-align: center;
  left: 0;
  top: 52%;
  width: 100%;
}
.content input[type=file] {
  display: none;
}
a.back {
  width: 32px;
  height: 32px;
  background: url(assets/icons.svg) no-repeat -192px 0;
  position: absolute;
  cursor: pointer;
  top: 50px;
  left: 50%;
  z-index: 10;
  opacity: 0.8;
  margin-left: -16px;
  display: none;
}
a.back:hover {
  opacity: 1;
}
input {
  font-family: Arial;
}

/* Conditional classes */

[class*="if-"] {
  display: none;
}
body.send .if-send {
  display: block;
}
body.receive .if-receive {
  display: block;
}

/* buttons */

.button {
  width: 240px;
  height: 70px;
  text-align: center;
  text-decoration: none !important;
  color: #fff !important;
  text-transform: uppercase;
  font-weight: bold;
  border-radius: 1px;
  display: block;
  line-height: 70px;
  box-shadow: 3px 3px 0 rgba(0, 0, 0, 0.08);
  cursor: pointer;
  font-size: 18px;
  margin: 10px auto;
  opacity: 0.9;
}
.button:hover {
  opacity: 1;
}
.button::before {
  content: '';
  background: url(assets/icons.svg) no-repeat;
  display: inline-block;
  width: 32px;
  height: 32px;
  vertical-align: middle;
  padding-right: 13px;
}
.button.green { background-color: #92cd84; }
.button.magenta { background-color: #e661b7; }
.button.blue { background-color: #798dd7; }
.button.red { background-color: #c15645; }
.button.browse { width: 180px; }
.button.process { width: 190px; }
.button.download { width: 216px; }
.button.upload { width: 180px; }
.button.send::before { background-position: 0 0; }
.button.receive::before { background-position: -96px 0; }
.button.browse::before { background-position: -240px 0; }
.button.process::before { background-position: -142px 0; }
.button.download::before { background-position: -48px 0; }
.button.upload::before { background-position: -190px 0; }
.button {
  transition: background-color 0.2s, width 0.3s ease-out;
}

/* steps */

#step1 {
  background-color: #75c0d1;
}
body.send #step2 {
  background-color: #9ad58c;
}
body.receive #step2 {
  background-color: #d5d788;
}
.input-group {
  width: 426px !important;
  margin: 12px auto 10px;
  height: 62px;
  box-shadow: 3px 3px 0 rgba(0, 0, 0, 0.05);
}
#step2 input[type=url] {
  background-color: #fff;
  border: none;
  padding: 8px 10px;
  padding-right: 0px;
  line-height: 1;
  font: inherit;
  display: inline-block;
  outline: none;
  width: 426px;
  border-radius: 2px;
  font-size: 36px;
  color: #555;
}
#step2 .button {
  cursor: default;
  opacity: 1;
}
#step3 {
  background-color: #9ad58c;
}
.content {
  margin-top: -90px;
}

/* footer */

footer {
  width: 770px;
  font: normal 16px Arial, Helvetica, sans-serif;
  padding: 15px 35px;
  position: fixed;
  bottom: 0;
  left: 50%;
  margin-left: -420px;
  background-color: #1f1f1f;
  background-image: linear-gradient(to bottom, #1f1f1f, #101010);
  border-radius: 2px 2px 0 0;
  box-shadow: 0 -1px 4px rgba(0, 0, 0, 0.4);
  z-index: 1;
  opacity: 0;
}

/* Misc */

a.github {
  opacity: 0.5;
  color: black;
  font-weight: bold;
  text-decoration: none;
}
a.github:hover {
  text-decoration: underline;
}
a.github::before {
  content: '';
  background: url(assets/github.png) no-repeat;
  background-size: 10px;
  display: inline-block;
  width: 12px;
  height: 10px;
  margin-left: 2px;
}
#total-downloads {
  font-weight: bold;
}