h1::before, h2::before, h3::before, h4::before, h5::before, h6::before {
    content: '';
    display: inline-block;
    width: 0;
    height: 0;
    margin-right: 8px; /* space between triangle and text */
    vertical-align: middle;
    border-top: 6px solid transparent;
    border-bottom: 6px solid transparent;
    border-left: 10px solid; /* color will be set per heading */
}

h1::before { border-left-color: #e74c3c; }  /* Red */
h2::before { border-left-color: #3498db; }  /* Blue */
h3::before { border-left-color: #2ecc71; }  /* Green */
h4::before { border-left-color: #f1c40f; }  /* Yellow */
h5::before { border-left-color: #9b59b6; }  /* Purple */
h6::before { border-left-color: #e67e22; }  /* Orange */