.append jquery not working code example

Example 1: css vertical-align not working

<div class="outer">
   <div class="inner"/>
</div>

.outer {
  display : flex;
  align-items : center;
  justify-content: center;
}

Example 2: js modulo not working

// The JS % operater is REMAINDER not MODULO
// For modulo behaviour use
function mod(n, m) {
  return ((n % m) + m) % m;
}