CSS.css

html, body {
  margin: 0;
  padding: 0;
  background: #faf8ef;
  color: #776e65;
  font-family: "Clear Sans", "Helvetica Neue", Arial, sans-serif;
  font-size: 18px;
}

body {
  margin: 20px 0;  
}

.heading:after {
  content: "";
  display: block;
  clear: both;
}

h1.title {
  font-size: 80px;
  font-weight: bold;
  margin: 0;
  display: block;
  float: left;
}

@-webkit-keyframes move-up {
  0% {
    top: 25px;
    opacity: 1;
  }

  100% {
    top: -50px;
    opacity: 0;
  }
}
@-moz-keyframes move-up {
  0% {
    top: 25px;
    opacity: 1;
  }

  100% {
    top: -50px;
    opacity: 0;
  }
}
@keyframes move-up {
  0% {
    top: 25px;
    opacity: 1;
  }

  100% {
    top: -50px;
    opacity: 0;
  }
}
.score-container {
  position: relative;
  float: right;
  background: #bbada0;
  padding: 15px 25px;
  font-size: 25px;
  height: 25px;
  line-height: 47px;
  font-weight: bold;
  border-radius: 3px;
  color: white;
  margin-top: 8px;
}
.score-container:after {
  position: absolute;
  width: 100%;
  top: 10px;
  left: 0;
  content: "Score";
  text-transform: uppercase;
  font-size: 13px;
  line-height: 13px;
  text-align: center;
  color: #eee4da;
}
.score-container .score-addition {
  position: absolute;
  right: 30px;
  color: red;
  font-size: 25px;
  line-height: 25px;
  font-weight: bold;
  color: rgba(119, 110, 101, 0.9);
  z-index: 100;
  -webkit-animation: move-up 600ms ease-in;
  -moz-animation: move-up 600ms ease-in;
  -webkit-animation-fill-mode: both;
  -moz-animation-fill-mode: both;
}

p {
  margin-top: 0;
  margin-bottom: 10px;
  line-height: 1.65;
}

a {
  color: #776e65;
  font-weight: bold;
  text-decoration: underline;
  cursor: pointer;
}

strong.important {
  text-transform: uppercase;
}

hr {
  border: none;
  border-bottom: 1px solid #d8d4d0;
  margin-top: 20px;
  margin-bottom: 30px;
}

.container {
  width: 500px;
  margin: 0 auto;
}

@-webkit-keyframes fade-in {
  0% {
    opacity: 0;
  }

  100% {
    opacity: 1;
  }
}
@-moz-keyframes fade-in {
  0% {
    opacity: 0;
  }

  100% {
    opacity: 1;
  }
}
@keyframes fade-in {
  0% {
    opacity: 0;
  }

  100% {
    opacity: 1;
  }
}
.game-container {
  margin-top: 10px;
  position: relative;
  padding: 15px;
  cursor: default;
  -webkit-touch-callout: none;
  -webkit-user-select: none;
  -moz-user-select: none;
  background: #bbada0;
  border-radius: 6px;
  width: 500px;
  height: 500px;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
}
.game-container .game-message {
  display: none;
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  background: rgba(238, 228, 218, 0.5);
  z-index: 100;
  text-align: center;
  -webkit-animation: fade-in 800ms ease 1200ms;
  -moz-animation: fade-in 800ms ease 1200ms;
  -webkit-animation-fill-mode: both;
  -moz-animation-fill-mode: both;
}
.game-container .game-message p {
  font-size: 60px;
  font-weight: bold;
  height: 60px;
  line-height: 60px;
  margin-top: 222px;
}
.game-container .game-message .lower {
  display: block;
  margin-top: 59px;
}
.game-container .game-message a {
  display: inline-block;
  background: #8f7a66;
  border-radius: 3px;
  padding: 0 20px;
  text-decoration: none;
  color: #f9f6f2;
  height: 40px;
  line-height: 42px;
  margin-left: 9px;
}
.game-container .game-message.game-won {
  background: rgba(237, 194, 46, 0.5);
  color: #f9f6f2;
}
.game-container .game-message.game-won, .game-container .game-message.game-over {
  display: block;
}

.grid-container {
  position: absolute;
  z-index: 1;
}

.grid-row {
  margin-bottom: 15px;
}
.grid-row:last-child {
  margin-bottom: 0;
}
.grid-row:after {
  content: "";
  display: block;
  clear: both;
}

.grid-cell {
  width: 106.25px;
  height: 106.25px;
  margin-right: 15px;
  float: left;
  border-radius: 3px;
  background: rgba(238, 228, 218, 0.35);
}
.grid-cell:last-child {
  margin-right: 0;
}

.tile-container {
  position: absolute;
  z-index: 2;
}

.tile {
  width: 106.25px;
  height: 106.25px;
  line-height: 116.25px;
}
.tile.tile-position-1-1 {
  position: absolute;
  left: 0px;
  top: 0px;
}
.tile.tile-position-1-2 {
  position: absolute;
  left: 0px;
  top: 121px;
}
.tile.tile-position-1-3 {
  position: absolute;
  left: 0px;
  top: 243px;
}
.tile.tile-position-1-4 {
  position: absolute;
  left: 0px;
  top: 364px;
}
.tile.tile-position-2-1 {
  position: absolute;
  left: 121px;
  top: 0px;
}
.tile.tile-position-2-2 {
  position: absolute;
  left: 121px;
  top: 121px;
}
.tile.tile-position-2-3 {
  position: absolute;
  left: 121px;
  top: 243px;
}
.tile.tile-position-2-4 {
  position: absolute;
  left: 121px;
  top: 364px;
}
.tile.tile-position-3-1 {
  position: absolute;
  left: 243px;
  top: 0px;
}
.tile.tile-position-3-2 {
  position: absolute;
  left: 243px;
  top: 121px;
}
.tile.tile-position-3-3 {
  position: absolute;
  left: 243px;
  top: 243px;
}
.tile.tile-position-3-4 {
  position: absolute;
  left: 243px;
  top: 364px;
}
.tile.tile-position-4-1 {
  position: absolute;
  left: 364px;
  top: 0px;
}
.tile.tile-position-4-2 {
  position: absolute;
  left: 364px;
  top: 121px;
}
.tile.tile-position-4-3 {
  position: absolute;
  left: 364px;
  top: 243px;
}
.tile.tile-position-4-4 {
  position: absolute;
  left: 364px;
  top: 364px;
}

.tile {
  border-radius: 3px;
  background: #eee4da;
  text-align: center;
  font-weight: bold;
  z-index: 10;
  font-size: 55px;
  -webkit-transition: 100ms ease-in-out;
  -moz-transition: 100ms ease-in-out;
  -webkit-transition-property: top, left;
  -moz-transition-property: top, left;
}
.tile.tile-2 {
  background: #eee4da;
  box-shadow: 0 0 30px 10px rgba(243, 215, 116, 0), inset 0 0 0 1px rgba(255, 255, 255, 0);
}
.tile.tile-4 {
  background: #ede0c8;
  box-shadow: 0 0 30px 10px rgba(243, 215, 116, 0), inset 0 0 0 1px rgba(255, 255, 255, 0);
}
.tile.tile-8 {
  color: #f9f6f2;
  background: #f2b179;
}
.tile.tile-16 {
  color: #f9f6f2;
  background: #f59563;
}
.tile.tile-32 {
  color: #f9f6f2;
  background: #f67c5f;
}
.tile.tile-64 {
  color: #f9f6f2;
  background: #f65e3b;
}
.tile.tile-128 {
  color: #f9f6f2;
  background: #edcf72;
  box-shadow: 0 0 30px 10px rgba(243, 215, 116, 0.2381), inset 0 0 0 1px rgba(255, 255, 255, 0.14286);
  font-size: 45px;
}
@media screen and (max-width: 480px) {
  .tile.tile-128 {
    font-size: 25px;
  }
}
.tile.tile-256 {
  color: #f9f6f2;
  background: #edcc61;
  box-shadow: 0 0 30px 10px rgba(243, 215, 116, 0.31746), inset 0 0 0 1px rgba(255, 255, 255, 0.19048);
  font-size: 45px;
}
@media screen and (max-width: 480px) {
  .tile.tile-256 {
    font-size: 25px;
  }
}
.tile.tile-512 {
  color: #f9f6f2;
  background: #edc850;
  box-shadow: 0 0 30px 10px rgba(243, 215, 116, 0.39683), inset 0 0 0 1px rgba(255, 255, 255, 0.2381);
  font-size: 45px;
}
@media screen and (max-width: 480px) {
  .tile.tile-512 {
    font-size: 25px;
  }
}
.tile.tile-1024 {
  color: #f9f6f2;
  background: #edc53f;
  box-shadow: 0 0 30px 10px rgba(243, 215, 116, 0.47619), inset 0 0 0 1px rgba(255, 255, 255, 0.28571);
  font-size: 35px;
}
@media screen and (max-width: 480px) {
  .tile.tile-1024 {
    font-size: 15px;
  }
}
.tile.tile-2048 {
  color: #f9f6f2;
  background: #edc22e;
  box-shadow: 0 0 30px 10px rgba(243, 215, 116, 0.55556), inset 0 0 0 1px rgba(255, 255, 255, 0.33333);
  font-size: 35px;
}
@media screen and (max-width: 480px) {
  .tile.tile-2048 {
    font-size: 15px;
  }
}

@-webkit-keyframes appear {
  0% {
    opacity: 0;
    -webkit-transform: scale(0);
    -moz-transform: scale(0);
  }

  100% {
    opacity: 1;
    -webkit-transform: scale(1);
    -moz-transform: scale(1);
  }
}
@-moz-keyframes appear {
  0% {
    opacity: 0;
    -webkit-transform: scale(0);
    -moz-transform: scale(0);
  }

  100% {
    opacity: 1;
    -webkit-transform: scale(1);
    -moz-transform: scale(1);
  }
}
@keyframes appear {
  0% {
    opacity: 0;
    -webkit-transform: scale(0);
    -moz-transform: scale(0);
  }

  100% {
    opacity: 1;
    -webkit-transform: scale(1);
    -moz-transform: scale(1);
  }
}
.tile-new {
  -webkit-animation: appear 200ms ease 100ms;
  -moz-animation: appear 200ms ease 100ms;
  -webkit-animation-fill-mode: both;
  -moz-animation-fill-mode: both;
}

@-webkit-keyframes pop {
  0% {
    -webkit-transform: scale(0);
    -moz-transform: scale(0);
  }

  50% {
    -webkit-transform: scale(1.2);
    -moz-transform: scale(1.2);
  }

  100% {
    -webkit-transform: scale(1);
    -moz-transform: scale(1);
  }
}
@-moz-keyframes pop {
  0% {
    -webkit-transform: scale(0);
    -moz-transform: scale(0);
  }

  50% {
    -webkit-transform: scale(1.2);
    -moz-transform: scale(1.2);
  }

  100% {
    -webkit-transform: scale(1);
    -moz-transform: scale(1);
  }
}
@keyframes pop {
  0% {
    -webkit-transform: scale(0);
    -moz-transform: scale(0);
  }

  50% {
    -webkit-transform: scale(1.2);
    -moz-transform: scale(1.2);
  }

  100% {
    -webkit-transform: scale(1);
    -moz-transform: scale(1);
  }
}
.tile-merged {
  z-index: 20;
  -webkit-animation: pop 200ms ease 100ms;
  -moz-animation: pop 200ms ease 100ms;
  -webkit-animation-fill-mode: both;
  -moz-animation-fill-mode: both;
}

.game-intro {
  margin-bottom: 0;
}

.game-explanation {
  margin-top: 50px;
}

@media screen and (max-width: 480px) {
  html, body {
    font-size: 15px;
  }

  body {
    margin: 20px 0;
    padding: 0 20px;
  }

  h1.title {
    font-size: 50px;
  }

  .container {
    width: 280px;
    margin: 0 auto;
  }

  .score-container {
    margin-top: 0;
  }

  .heading {
    margin-bottom: 10px;
  }

  .game-container {
    margin-top: 40px;
    position: relative;
    padding: 10px;
    cursor: default;
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -moz-user-select: none;
    background: #bbada0;
    border-radius: 6px;
    width: 280px;
    height: 280px;
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
  }
  .game-container .game-message {
    display: none;
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    background: rgba(238, 228, 218, 0.5);
    z-index: 100;
    text-align: center;
    -webkit-animation: fade-in 800ms ease 1200ms;
    -moz-animation: fade-in 800ms ease 1200ms;
    -webkit-animation-fill-mode: both;
    -moz-animation-fill-mode: both;
  }
  .game-container .game-message p {
    font-size: 60px;
    font-weight: bold;
    height: 60px;
    line-height: 60px;
    margin-top: 222px;
  }
  .game-container .game-message .lower {
    display: block;
    margin-top: 59px;
  }
  .game-container .game-message a {
    display: inline-block;
    background: #8f7a66;
    border-radius: 3px;
    padding: 0 20px;
    text-decoration: none;
    color: #f9f6f2;
    height: 40px;
    line-height: 42px;
    margin-left: 9px;
  }
  .game-container .game-message.game-won {
    background: rgba(237, 194, 46, 0.5);
    color: #f9f6f2;
  }
  .game-container .game-message.game-won, .game-container .game-message.game-over {
    display: block;
  }

  .grid-container {
    position: absolute;
    z-index: 1;
  }

  .grid-row {
    margin-bottom: 10px;
  }
  .grid-row:last-child {
    margin-bottom: 0;
  }
  .grid-row:after {
    content: "";
    display: block;
    clear: both;
  }

  .grid-cell {
    width: 57.5px;
    height: 57.5px;
    margin-right: 10px;
    float: left;
    border-radius: 3px;
    background: rgba(238, 228, 218, 0.35);
  }
  .grid-cell:last-child {
    margin-right: 0;
  }

  .tile-container {
    position: absolute;
    z-index: 2;
  }

  .tile {
    width: 57.5px;
    height: 57.5px;
    line-height: 67.5px;
  }
  .tile.tile-position-1-1 {
    position: absolute;
    left: 0px;
    top: 0px;
  }
  .tile.tile-position-1-2 {
    position: absolute;
    left: 0px;
    top: 68px;
  }
  .tile.tile-position-1-3 {
    position: absolute;
    left: 0px;
    top: 135px;
  }
  .tile.tile-position-1-4 {
    position: absolute;
    left: 0px;
    top: 203px;
  }
  .tile.tile-position-2-1 {
    position: absolute;
    left: 68px;
    top: 0px;
  }
  .tile.tile-position-2-2 {
    position: absolute;
    left: 68px;
    top: 68px;
  }
  .tile.tile-position-2-3 {
    position: absolute;
    left: 68px;
    top: 135px;
  }
  .tile.tile-position-2-4 {
    position: absolute;
    left: 68px;
    top: 203px;
  }
  .tile.tile-position-3-1 {
    position: absolute;
    left: 135px;
    top: 0px;
  }
  .tile.tile-position-3-2 {
    position: absolute;
    left: 135px;
    top: 68px;
  }
  .tile.tile-position-3-3 {
    position: absolute;
    left: 135px;
    top: 135px;
  }
  .tile.tile-position-3-4 {
    position: absolute;
    left: 135px;
    top: 203px;
  }
  .tile.tile-position-4-1 {
    position: absolute;
    left: 203px;
    top: 0px;
  }
  .tile.tile-position-4-2 {
    position: absolute;
    left: 203px;
    top: 68px;
  }
  .tile.tile-position-4-3 {
    position: absolute;
    left: 203px;
    top: 135px;
  }
  .tile.tile-position-4-4 {
    position: absolute;
    left: 203px;
    top: 203px;
  }

  .game-container {
    margin-top: 20px;
  }

  .tile {
    font-size: 35px;
  }

  .game-message p {
    font-size: 30px !important;
    height: 30px !important;
    line-height: 30px !important;
    margin-top: 90px !important;
  }
  .game-message .lower {
    margin-top: 30px !important;
  }