details { background-color: rgba(50, 150, 220, 0.08); margin-bottom: 0.5em; padding: 0 1em; overflow-y: hidden; /* Suppress margin-collapsing */ } details[open] { border-bottom: 1px solid rgba(0, 0, 128, 0.2); margin-bottom: 1em; } details summary { font-weight: bold; background-color: rgba(50, 150, 220, 0.1); border-color: rgba(0, 0, 128, 0.2); border-width: 1px; border-style: solid none; padding: 0.2em; margin: 0 -1em; } details summary:hover { background-color: rgba(50, 150, 220, 0.2); cursor: pointer; }