Great design!

This plugin has been a lifesaver because I was using Show-Hide/Collapse-Expand, which seems to have been abandoned after three years. It works immediately with the old bg_collapse markup, so just install it and deactivate Show-Hide.

With the help of Claude AI, I designed additional CSS code to reproduce almost the former layout:

/* --- Show Hide Accordion: port of bg-orange-button --- */

.shabm-wrap {
text-align: center;
margin: 1em 0;
}

.shabm-wrap .shabm-content {
text-align: left;
}

a.shabm-toggle,
a.shabm-toggle:visited {
display: inline-block;
cursor: pointer;
padding: 6px 24px;
font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
font-size: inherit;
line-height: normal;
letter-spacing: normal;
text-transform: none;
text-decoration: none !important;
text-shadow: 0 1px 0 #ffee66;
background: linear-gradient(to bottom, #ffec64 5%, #ffab23 100%);
background-color: #ffec64;
border: 1px solid #ffaa22;
border-radius: 8px;
box-shadow: inset 0 4px 0 0 #fff6af;
}

a.shabm-toggle:hover,
a.shabm-toggle:focus {
border-bottom: 1px solid #ffaa22 !important;
color: #72777c !important;
background: linear-gradient(to bottom, #ffab23 5%, #ffec64 100%) !important;
background-color: #ffab23 !important;
text-decoration: none !important;
outline: none;
box-shadow:
inset 0 1px 0 0 #fff6af,
0 10px 10px rgba(0, 0, 0, 0.25) !important;
}

a.shabm-toggle .shabm-icon {
position: relative;
bottom: 1px;
padding-right: 4px;
font-size: inherit;
}

This could be used (and made optional) in future versions of this plugin.

Once again, congratulations!