jira-kanban.css

.adg3 .ghx-column h2 {
	text-transform: none;
	font-size: 13px;
	color: #2e2e2e
}
.adg3 .ghx-column-headers .ghx-qty {
	background-color: #18cb3b;
	color: white;
	width: 20px;
	height: 20px;
	text-align: center;
	line-height: 20px;
	border-radius: 10px;
}
.adg3 .ghx-column-headers .ghx-column {
	background-color: #e0e0e0;
}
.adg3 .ghx-narrow-card .ghx-issue .ghx-stat-fields > .ghx-row.ghx-stat-1 {
	display: none;
}	

jira-kanban.js

(function() {
  const css = `
  .adg3 .ghx-column h2 {
    text-transform: none;
    font-size: 13px;
    color: #2e2e2e
  }
  .adg3 .ghx-column-headers .ghx-qty {
    background-color: #18cb3b;
    color: white;
    width: 20px;
    height: 20px;
    text-align: center;
    line-height: 20px;
    border-radius: 10px;
    transform: translateY(-2px);
  }
  .adg3 .ghx-column-headers .ghx-column {
    background-color: #e0e0e0;
  }
  .adg3 .ghx-narrow-card .ghx-issue .ghx-stat-fields > .ghx-row.ghx-stat-1 {
	  display: none;
  }`;
  const style = document.createElement('style');
  style.textContent = css;
  document.querySelector('head').appendChild(style);
})();
// transpile at https://babeljs.io/en/repl
// convert to bookmarklet at http://bookmarklets.org/maker/