style.css

body {
  max-width: 800px;
  margin: 0 auto 0 auto;
}

#icon-preview {
  height: calc(2.25rem + 2px);
  width: calc(2.25rem + 2px);
  object-fit: contain;
}

mark {
  background-color: #fff9d8ee;
}

/* advanced options are initially hidden */
.adv-hidden {
  display: none;
}

#post-checkbox {
  margin-bottom: .5rem;
}

input[type=file] {
  display: none;
}

label[for=input-file-icon] {
  width: 100%;
  -moz-appearance: button;
}

#instructions {
  display: none;
}

#arrow {
  position: fixed;
  top: 40px;
  left: 50%;
  margin-left:-20px;
  width: 40px;
  height: 40px;
  background-image: url(icons/arrow.svg);
  background-size: contain;
  animation: bounce 2s infinite;
}

#info {
  margin: auto;
  padding-top: 100px;
  width: 800px;
}

#info p {
  margin-top: 0.5em;
}

@keyframes bounce {
  0%, 20%, 50%, 80%, 100% {
    transform: translateY(0);
  }
  40% {
    transform: translateY(-30px);
  }
  60% {
    transform: translateY(-15px);
  }
}