.study-section-links{display:flex;flex-wrap:wrap;gap:12px;margin:26px 0 36px}
.study-section-links a{background:var(--surface);border:1px solid var(--line);border-radius:30px;padding:12px 18px;text-decoration:none;font-size:14px;font-weight:600;min-height:44px}
.study-library-section{margin:28px 0 48px;scroll-margin-top:24px}
.study-library-section>.section-bar{align-items:end;gap:20px;flex-wrap:wrap}
.study-library-section label{display:grid;gap:8px;min-width:220px;font-size:14px}
.study-library-section select{border:1px solid var(--line);background:var(--surface);padding:12px;border-radius:12px;font-size:16px;min-height:48px;color:inherit}
.book-study-guide{border:1px solid var(--line);background:var(--surface-soft);border-radius:18px;margin:20px 0;overflow:hidden}
.book-study-guide>summary{cursor:pointer;padding:18px 22px;font-weight:650;line-height:1.5}
.book-study-guide>summary span{font-size:14px;font-weight:500;border:1px solid var(--line);border-radius:20px;padding:4px 9px;margin-left:8px;white-space:nowrap}
.book-guide-body{border-top:1px solid var(--line);padding:22px;line-height:1.75}
.book-guide-body h4,.chapter-study-lab h4{font-size:16px;margin:24px 0 8px;font-family:var(--sans)}
.book-guide-body>p:first-of-type{margin-top:0}
.book-guide-body .plain-button{font-size:14px;min-height:44px}
.study-book-progress{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;margin:22px 0 16px;font-size:14px}
.study-chapter-picker{display:grid;grid-template-columns:repeat(auto-fill,minmax(52px,1fr));gap:8px}
.study-chapter-picker button{min-height:48px;border:1px solid var(--line);background:var(--surface);border-radius:12px;color:var(--muted);font:inherit;cursor:pointer}
.study-chapter-picker .is-read{background:var(--surface);border-color:var(--line)}
.study-path-grid,.study-skill-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px;margin-top:24px}
.study-path,.study-skill{border:1px solid var(--line);background:var(--surface);border-radius:18px;overflow:hidden}
.study-path>summary{display:flex;justify-content:space-between;align-items:center;gap:12px;cursor:pointer;padding:22px;min-height:100px;list-style:none}
.study-path>summary::-webkit-details-marker{display:none}
.study-path[open]>summary{border-bottom:1px solid var(--line)}
.study-path strong{display:block;font-size:18px;line-height:1.45}
.study-path small{display:block;font-size:12px;color:var(--muted);margin-top:6px}
.study-path>div{padding:8px 22px 20px;line-height:1.65}
.study-path ol{padding-left:24px}
.study-path li .plain-button{padding:8px 0;min-height:44px}
.study-skill{padding:26px;line-height:1.65}
.study-skill h3{font-size:23px;margin:16px 0 8px}
.study-skill-number{display:grid;place-items:center;background:var(--surface);border-radius:50%;width:36px;height:36px;font-weight:650}
.study-skill-aim{font-weight:600}
.study-skill details{border-top:1px solid var(--line);margin-top:14px;padding-top:14px;font-size:14px}
.study-skill summary,.chapter-study-lab summary{cursor:pointer;min-height:44px;align-content:center;font-weight:600}
.chapter-study-lab{border:1px solid var(--line);border-radius:14px;margin:20px 0;padding:12px 18px;line-height:1.65}
.chapter-study-lab li{margin:10px 0}
.chapter-study-lab small{display:block;font-size:12px;margin-top:10px}
.study-library-next>div{display:flex;flex-wrap:wrap;gap:12px;margin-top:20px}
.study-library-invitation{display:flex;justify-content:space-between;align-items:center;gap:24px;border:1px solid var(--line);border-radius:20px;padding:24px;margin:26px 0;background:var(--surface-soft)}
.study-library-invitation button{flex-shrink:0}
@media(max-width:700px){.study-path-grid,.study-skill-grid{grid-template-columns:1fr}.study-library-invitation{display:block;padding:22px}.study-library-invitation button{margin-top:14px}.study-library-section label{width:100%}.book-study-guide>summary{padding:16px}.book-study-guide>summary span{display:table;margin:8px 0 0}.book-guide-body{padding:18px}.study-skill{padding:22px}.study-section-links{gap:8px}.study-section-links a{font-size:14px;padding:10px 14px}}
.study-library-page{max-width:1160px;margin:auto;color:var(--ink)}
.study-library-intro{max-width:740px;font-size:17px;line-height:1.75;color:var(--muted)}
.study-library-next{border:1px solid var(--line);border-radius:22px;background:var(--surface);padding:30px;margin:32px 0}
.study-library-invitation h2{font-size:27px;letter-spacing:-.025em;margin:10px 0}
.study-library-invitation p{color:var(--muted);line-height:1.7;margin:10px 0;max-width:600px}