style.css

body, html {
  width: 100%;
  height: 100%;
  font-family: 'Montserrat', sans-serif;
}

body {
  background: url(https://bureau.ru/var/files/img1532613761) no-repeat center center fixed;
  background-size: cover;
}

.startup {
  color: rgba(255, 255, 255, 0.95);
  font-family: 'Montserrat', sans-serif;
  font-size: 2em;
  font-weight: bold;
  transition: all 0.5s;
  cursor: pointer;
}

.startup:hover {
  transform: scale(1.05);
}

.btn-primary {
  background-color: blue;
  border-color: blue;
  transition: all 0.5s;
}

.btn-primary:hover {
  transform: scale(1.05);
  background-color: purple;
  border-color: purple;
  border-width: 1px;
}

.btn {
  font-weight: bold;
  border-radius: 300px;
}

.logo {
  text-align: center;
  color: rgba(0, 0, 0, 0.5);
  font-family: 'Montserrat', sans-serif;
  font-weight: bold;
  font-size: 2.4em;
  cursor: pointer;
  background-color: rgba(255, 255, 255, 0.2);
  padding-bottom: 6px;
}

.sticky {
  position: fixed;
  top: 0;
  width: 100%;
}

footer {
  clear: both;
  text-align: center;
  color: rgba(255, 255, 255, 0.8);
  font-family: 'Montserrat', sans-serif;
  font-weight: bold;
  cursor: pointer;
}