.theory-panel{border:1px solid #d7d8e1;border-radius:12px;background:#fff;overflow:hidden;color:#28263b}
.theory-panel summary{display:flex;align-items:center;gap:10px;min-height:48px;padding:10px 13px;cursor:pointer;font-size:.9rem;font-weight:750;line-height:1.3;list-style:none;background:#f7f7fa}
.theory-panel summary::-webkit-details-marker{display:none}
.theory-panel summary:focus-visible{outline:3px solid rgba(255,114,12,.35);outline-offset:-3px}
.theory-icon{display:inline-grid;place-items:center;flex:0 0 22px;width:22px;height:22px;border-radius:50%;background:#444159;color:#fff;font-family:Georgia,serif;font-size:.85rem;font-weight:700}
.theory-chevron{width:9px;height:9px;margin-left:auto;border-right:2px solid #5e5c70;border-bottom:2px solid #5e5c70;transform:rotate(45deg) translateY(-2px);transition:transform .18s ease}
.theory-panel[open] .theory-chevron{transform:rotate(225deg) translate(-2px,-2px)}
.theory-content{padding:14px 15px 16px;border-top:1px solid #e5e5eb}
.theory-content h3{margin:0 0 7px;font-size:1rem;line-height:1.3;color:#302e48}
.theory-content p{margin:0 0 10px;font-size:.9rem;line-height:1.55}
.theory-content .theory-source{font-size:.78rem;color:#686678}
.theory-link{display:inline-flex;align-items:center;gap:6px;color:#a94800;font-size:.85rem;font-weight:750;text-decoration:none}
.theory-link:hover{text-decoration:underline}

@media (min-width:961px){
  .question .qbody.has-theory-panel{display:grid;grid-template-columns:minmax(0,1fr) 300px;column-gap:18px;align-items:start}
  .question .qbody.has-theory-panel>:not(.theory-panel){grid-column:1}
  .question .qbody.has-theory-panel>.theory-panel{grid-column:2;grid-row:1 / span 30;position:sticky;top:72px}
}

@media (max-width:960px){
  .theory-panel{margin:14px 0 4px}
  .theory-panel summary{min-height:52px;padding:12px 14px}
  .theory-content{padding:15px 16px 17px}
}