gecko-dev/browser/themes/linux/aboutSocialError.css

body {
  background-color: rgb(241, 244, 248);
  margin-top: 2em;
  font: message-box;
  font-size: 100%;
}

p {
  font-size: .8em;
}

#error-box {
  background: url('chrome://global/skin/icons/information-24.png') no-repeat left 4px;
  -moz-padding-start: 30px;
}

#error-box:-moz-locale-dir(rtl) {
  background-position: right 4px;
}

#main-error-msg {
  color: #4b4b4b;
  font-weight: bold;
}


#button-box {
  text-align: center;
  width: 75%;
  margin: 0 auto;
}

@media all and (min-width: 300px) {
  #error-box {
    max-width: 50%;
    margin: 0 auto;
    background-image: url('chrome://global/skin/icons/information-32.png');
    min-height: 36px;
    -moz-padding-start: 38px;
  }

  button {
    width: auto !important;
    min-width: 150px;
  }
}

@media all and (min-width: 780px) {
  #error-box {
    max-width: 30%;
  }
}

button {
  font: message-box;
  font-size: 0.6875em;
  -moz-appearance: none;
  -moz-user-select: none;
  width: 100%;
  margin: 2px 0;
  padding: 2px 6px;
  line-height: 1.2;
  background-color: hsla(210,30%,95%,.1);
  background-image: linear-gradient(hsla(0,0%,100%,.6), hsla(0,0%,100%,.1));
  background-clip: padding-box;
  border: 1px solid hsla(210,15%,25%,.4);
  border-color: hsla(210,15%,25%,.3) hsla(210,15%,25%,.35) hsla(210,15%,25%,.4);
  border-radius: 3px;
  box-shadow: 0 1px 0 hsla(0,0%,100%,.3) inset,
              0 0 0 1px hsla(0,0%,100%,.3) inset,
              0 1px 0 hsla(0,0%,100%,.1);

  transition-property: background-color, border-color, box-shadow;
  transition-duration: 150ms;
  transition-timing-function: ease;

}

button:hover {
  background-color: hsla(210,30%,95%,.8);
  border-color: hsla(210,15%,25%,.45) hsla(210,15%,25%,.5) hsla(210,15%,25%,.55);
  box-shadow: 0 1px 0 hsla(0,0%,100%,.3) inset,
              0 0 0 1px hsla(0,0%,100%,.3) inset,
              0 1px 0 hsla(0,0%,100%,.1),
              0 0 3px hsla(210,15%,25%,.1);
  transition-property: background-color, border-color, box-shadow;
  transition-duration: 150ms;
  transition-timing-function: ease;
}

button:hover:active {
  background-color: hsla(210,15%,25%,.2);
  box-shadow: 0 1px 1px hsla(210,15%,25%,.2) inset,
              0 0 2px hsla(210,15%,25%,.4) inset;
  transition-property: background-color, border-color, box-shadow;
  transition-duration: 10ms;
  transition-timing-function: linear;
}