.lesson-chapters{margin:14px 0 0;border:1px solid #c9ddd3;border-radius:16px;background:#fff;overflow:hidden;box-shadow:0 3px 12px #163f3505}
.lesson-chapters summary{display:flex;align-items:center;justify-content:space-between;gap:12px;list-style:none;padding:15px 16px;min-height:52px;box-sizing:border-box;font-family:inherit;font-weight:700;font-size:14px;line-height:1.5;color:#164b39;cursor:pointer;touch-action:manipulation;-webkit-tap-highlight-color:transparent}
.lesson-chapters summary::-webkit-details-marker{display:none}.lesson-chapters summary::after{content:"";width:7px;height:7px;border-right:2px solid #4d7968;border-bottom:2px solid #4d7968;transform:rotate(45deg);flex:0 0 7px;margin-right:3px;transition:transform .18s ease}.lesson-chapters[open] summary::after{transform:rotate(225deg)}
.lesson-chapters[open] summary{border-bottom:1px solid #e4ede7;margin-bottom:10px}
.lesson-chapter-list{display:grid;gap:8px;padding:0 10px 12px}
.lesson-chapter-list button{appearance:none;-webkit-appearance:none;display:grid;grid-template-columns:48px minmax(0,1fr) 12px;align-items:center;gap:10px;text-align:left;width:100%;min-height:54px;box-sizing:border-box;padding:10px 12px;background:#f5f8f5;color:#173e33;border:1px solid #e7eee8;border-radius:11px;font-family:inherit;font-size:14px;font-weight:550;line-height:1.5;cursor:pointer;touch-action:manipulation;-webkit-tap-highlight-color:transparent;transition:background .16s ease,border-color .16s ease,box-shadow .16s ease}
.lesson-chapter-list button span{display:inline-flex;align-items:center;justify-content:center;padding:5px 4px;border-radius:7px;background:#e7f0e9;color:#28614b;font-size:12px;font-weight:750;line-height:1.4;white-space:nowrap;font-variant-numeric:tabular-nums}
.lesson-chapter-list button::after{content:"";width:0;height:0;border-top:4px solid transparent;border-bottom:4px solid transparent;border-left:6px solid #719382;justify-self:center}
.lesson-chapter-list button[aria-pressed=true]{background:#e8f5ed;border-color:#428364;box-shadow:inset 3px 0 #16734f}.lesson-chapter-list button[aria-pressed=true] span{background:#166547;color:#fff}.lesson-chapter-list button[aria-pressed=true]::after{border-left-color:#166547}
@media(hover:hover){.lesson-chapter-list button:hover{background:#ebf3ed;border-color:#a8c6b5}}
.lesson-chapters summary:focus-visible,.lesson-chapter-list button:focus-visible{outline:3px solid #c39b3a;outline-offset:-3px}
.lesson-chapter-status{font-family:inherit;font-size:13px;line-height:1.6;color:#365d4a;padding:0 14px}.lesson-chapter-status:empty{display:none}
@media(max-width:420px){.lesson-chapters summary{padding:13px 12px;font-size:14px}.lesson-chapter-list{padding:0 8px 10px;gap:7px}.lesson-chapter-list button{grid-template-columns:44px minmax(0,1fr) 10px;gap:8px;padding:10px;font-size:13px;min-height:52px}}
@media(prefers-reduced-motion:reduce){.lesson-chapters summary::after,.lesson-chapter-list button{transition:none}}