JSFiddle - React, Tailwind, and code Playground

HTML

<h1>Anti-Idle Garden Breeding</h1>
<form><table>
    <tr><td>First seed:</td><td><input id=seed1 size=6 onkeyup="breed();"></td></tr>
    <tr><td>Second seed:</td><td><input id=seed2 size=6 onkeyup="breed();"></td>
  </table></form>
<hr>
<div id=results></div>

CSS

body { padding:1em; font-family:sans; }

JavaScript

function $i(a){return document.getElementById(a);}
function breed() {
  var p1, p2, ca, ctext;
  p1 = parseInt($i('seed1').value,10);
  p2 = parseInt($i('seed2').value,10);
  ctext = "Child seeds: ";
  if (p1 > 0 && p1 < 76 && p2 > 0 && p2 < 76) {
    ca = ((p1 + p2) / 2);
    if (Math.floor(ca) == ca - 0.5) {
      ctext = ctext + Math.floor(ca).toString() + ", " + Math.ceil(ca).toString();
    }
    else {
      ctext = ctext + Math.round(ca).toString() + ", " + Math.round(ca).toString();
    }
    ctext = ctext + ", ";
    ca = ca + 37.5;
    if (ca > 75) {
      ca = ca - 75;
    }
    if (Math.floor(ca) == ca - 0.5) {
      ctext = ctext + Math.floor(ca).toString() + ", " + Math.ceil(ca).toString(); 
    }
    else {
      ctext = ctext + Math.round(ca).toString() + ", " + Math.round(ca).toString();
    }
  }
  else {
    ctext = ctext + "none"
  }
  $i('results').innerHTML = ctext;
}