main.css

/* Mobile First Media Queries */

/* Base style */
{ ... }

/* Larger than mobile screen */
@media (min-width: 40.0rem) { ... }

/* Larger than tablet screen */
@media (min-width: 80.0rem) { ... }

/* Larger than desktop screen */
@media (min-width: 120.0rem) { ... }

body {
 background: #333;
 margin: 0;
 padding: 0rem 0rem;
}

#linkarea {
  color: #DDD;
  padding: 0.5rem 1rem;
  width: 100%;
  overflow: visible;
  border-left-color: #FFF;
  border-left-style: solid;
  border-left-width: 0.3rem;
  font-size: 1.6rem;
  font-weight: bolder;
  font-family: monospace;
  word-wrap: normal;
  display: block;
  text-align: center;
  margin-bottom: 5rem;
  background: #666;
}

a {
  color: #DDD;
}
a:hover {
  color: #FFF;
}
a:focus {
  color: #FFF;
}

header {
  color: white;
  margin: 1rem;
  display: flex;
  flex-wrap: wrap;
  /*margin-top: 2.5rem;*/
}

header > * {
  margin: 1rem;
  margin: auto auto;
}

header > a {
  color: inherit;
  padding: 3rem 2rem;
}

header > a:hover {
  color: inherit;
  background: #444;
}

header > a:focus {
  outline: none;
  color: black;
}

header > * > * {
  margin: inherit;
}

header > * > ol {
  padding: 0.5rem 1rem;
}

header > * > ol:hover {
  background: #444;
}

header > * > ol > span {
  color: lightgrey;
  font-weight: bold;
}

main {
  text-align: center;
}
main > img {
  background: url(checkboard_bg.png);
  background-repeat: repeat;
  background-size: 2rem 2rem;
  max-width: 90%;
}
main > * {
  /*margin: auto;*/
}
main > .darkroom-container {
  width: 90%;
  margin: auto auto;
}

main > .darkroom-container > .darkroom-image-container > .canvas-container {
  background: url(checkboard_bg.png);
  background-repeat: repeat;
  background-size: 2rem 2rem;
}

.darkroom-toolbar {
  display: flex;
}

.darkroom-button-group {

}

.darkroom-button-default {
  padding-top: 0.5rem;
}

#DRAWBUTTON {
  padding-top: 0.25rem;
}

img.darkroom-button-icon {
  width: 32px;
  height: auto;
  padding: 8px;
}

input.color-picker {
  text-align: center;
  width: 9rem;
  padding: 0.5rem;
  border: none;
  border-radius: 1rem;
  margin: auto auto;
  display: none;
}


footer {
  margin-top: 5rem;
  height: 12rem;
  width: 100%;
  background-color: #444;
  background: linear-gradient(to bottom, #444, #333);
  padding: 1rem 3rem;
  display: flex;
  color: white;
  overflow: hidden;
}
footer > .contact-list > li {
  list-style-type: none;
}