message: update viewer.css for pdfjs v2.1.266
diff: line-height: 1.0;
  }
  -.textLayer > div {
  +.textLayer > span {
  color: transparent;
  position: absolute;
  white-space: pre;
  @@ -505,24 +505,24 @@ select {
  display: none;
  }
  -.pdfPresentationMode:-webkit-full-screen .textLayer > div {
  +.pdfPresentationMode:-webkit-full-screen .textLayer > span {
  cursor: none;
  }
  -.pdfPresentationMode:-moz-full-screen .textLayer > div {
  +.pdfPresentationMode:-moz-full-screen .textLayer > span {
  cursor: none;
  }
  -.pdfPresentationMode:-ms-fullscreen .textLayer > div {
  +.pdfPresentationMode:-ms-fullscreen .textLayer > span {
  cursor: none;
  }
  -.pdfPresentationMode:fullscreen .textLayer > div {
  +.pdfPresentationMode:fullscreen .textLayer > span {
  cursor: none;
  }
  .pdfPresentationMode.pdfPresentationModeControls > *,
  -.pdfPresentationMode.pdfPresentationModeControls .textLayer > div {
  +.pdfPresentationMode.pdfPresentationModeControls .textLayer > span {
  cursor: default;
  }
  @@ -1569,6 +1569,11 @@ html[dir='rtl'] .verticalToolbarSeparator {
  -webkit-overflow-scrolling: touch;
  }
  +#thumbnailView > a:active,
  +#thumbnailView > a:focus {
  + outline: 0;
  +}
  +
  .thumbnail {
  margin: 0 10px 5px 10px;
  }
  @@ -1991,19 +1996,19 @@ html[dir='rtl'] #documentPropertiesOverlay .row > * {
  mix-blend-mode: screen;
  }
  -#viewer.textLayer-visible .textLayer > div {
  +#viewer.textLayer-visible .textLayer > span {
  background-color: rgba(255, 255, 0, 0.1);
  color: black;
  border: solid 1px rgba(255, 0, 0, 0.5);
  box-sizing: border-box;
  }
  -#viewer.textLayer-hover .textLayer > div:hover {
  +#viewer.textLayer-hover .textLayer > span:hover {
  background-color: white;
  color: black;
  }
  -#viewer.textLayer-shadow .textLayer > div {
  +#viewer.textLayer-shadow .textLayer > span {
  background-color: rgba(255,255,255, .6);
  color: black;
  }
  @@ -2041,7 +2046,7 @@ html[dir='rtl'] #documentPropertiesOverlay .row > * {
  display: none;
  }
  -@media screen and (-webkit-min-device-pixel-ratio: 2), screen and (min-resolution: 2dppx) {
  +@media screen and (-webkit-min-device-pixel-ratio: 1.1), screen and (min-resolution: 1.1dppx) {
  /* Rules for Retina screens */
  .toolbarButton::before {
  -webkit-transform: scale(0.5);
  