h5p-php-library/styles/h5p-core-button.css

.h5p-core-button {
  font-size: 1em;
  line-height: 1.2;
  padding: 0.5em 1.25em;
  border-radius: 2em;

  background: #1a73d9;
  color: #ffffff;

  cursor: pointer;
  border: none;
  box-shadow: none;
  outline: none;

  display: inline-block;
  text-align: center;
  text-shadow: none;
  vertical-align: baseline;
  text-decoration: none;
}
.h5p-core-button:hover,
.h5p-core-button:focus {
  background: #1356a3;
  color: #fff;
  text-decoration: none;
  -webkit-transition: initial;
  transition: initial;
}
.h5p-core-button:active {
  position: relative;
  background: #104888;

  -webkit-box-shadow: inset 0 4px 0 #0e407a;
  -moz-box-shadow: inset 0 4px 0 #0e407a;
  box-shadow: inset 0 4px 0 #0e407a;
}

.h5p-core-button:before {
  font-family: 'H5P';
  padding-right: 0.15em;
  font-size: 1.5em;
  vertical-align: middle;
  line-height: 0.7;
}

.h5p-core-cancel-button {
  cursor: pointer;
  background: none;
  border: none;
  color: #a00;
  margin-right: 1em;
  font-size: 1em;
  text-decoration: none;
}

.h5p-core-cancel-button:hover,
.h5p-core-cancel-button:focus {
  background: none;
  border: none;
  color: #e40000;
}