.fraction {
  display: inline-block;
  text-align: center;
  vertical-align: middle;
  font-size: 0.95em;
  line-height: 1;
}
.fraction .top {
  display: block;
}
.fraction .bar {
  display: block;
  border-top: 1px solid #000;
  height: 1px;
  margin: 2px 0;
}
.fraction .bottom {
  display: block;
}

body {
    -webkit-user-select: none; /* Chrome, Safari */
    -moz-user-select: none;    /* Firefox */
    -ms-user-select: none;     /* Internet Explorer/Edge */
    user-select: none;         /* Standard syntax */
}

table.matrix {
  border-collapse: collapse;
  display: inline-table;
  margin: 0 4px;
  vertical-align: middle;
  font-family: "Cambria Math", "Times New Roman", serif;
}
table.matrix td {
  padding: 2px 6px;
  text-align: center;
  border: none;
}
table.matrix::before {
  content: "⎡";
  font-size: 1.2em;
  vertical-align: top;
}
table.matrix::after {
  content: "⎦";
  font-size: 1.2em;
  vertical-align: bottom;
}