.lesson-shell{max-width:1550px;margin:auto;padding:28px 34px}.lesson-intro p{font-size:13px;line-height:1.8;max-width:980px;color:#657b92}.lesson-tags{display:flex;flex-wrap:wrap;gap:6px}.lesson-tags a,.course-tags span{background:#eaf2fb;border-radius:4px;padding:4px 8px;font-size:11px;color:#46769e}.source-note{font-size:11px!important;color:#8c9bac!important}
.lesson-grid{display:grid;grid-template-columns:240px minmax(0,1fr);gap:22px;margin-top:23px}.lesson-nav{background:#fff;border:1px solid #e0e7ef;border-radius:10px;padding:18px;min-height:0;align-self:start}.lesson-nav>strong{font-size:12px}.lesson-nav nav{margin:12px 0}.lesson-nav a{display:block;font-size:12px;padding:10px 9px;border-radius:5px;line-height:1.7;color:#60788f}.lesson-nav a.active,.lesson-nav button.active{background:#eaf2fc;color:#286abc}.lesson-nav button{display:block;text-align:left;font-size:12px;line-height:1.7}.lesson-nav p{font-size:11px;line-height:1.8;color:#8495a6}.nav-divider{height:1px;background:#e5ebf2;margin:17px 0}.lesson-work{background:#fff;border:1px solid #e0e7ef;border-radius:10px;min-width:0;padding:20px}
.mode-bar{display:flex;gap:8px;border-bottom:1px solid #e4ebf3;padding-bottom:13px}.mode-bar button[aria-selected=true]{background:#286abc;color:#fff;border-color:#286abc}.mode-bar #zoom-stage{margin-left:auto}.step-info{margin:18px 0}.step-info span{color:#3775b3;font-size:11px}.step-info h2{font-size:20px;margin:8px 0}.step-info p{color:#61778e;font-size:13px;line-height:1.9;margin-bottom:14px}
.lesson-stage{position:relative;background:#f5f8fb;border:1px solid #dbe5ef;border-radius:8px;overflow:hidden;margin:auto;max-width:100%;width:fit-content}.lesson-stage img{display:block;max-width:100%;max-height:550px;width:auto;height:auto}.step-target{position:absolute;border:2px solid #f29b25;border-radius:5px;background:#ffb03916;box-shadow:0 0 0 4px #ffb03930;padding:0;color:transparent;min-width:20px;min-height:20px}.step-target:hover{background:#ffb03930}.step-target:focus-visible{outline:3px solid #286abc;outline-offset:3px}.step-target.read-target{background:#286abc;color:#fff;width:95%!important;height:auto!important;left:2.5%!important;top:auto!important;bottom:10px;padding:8px;font-size:12px;min-height:35px}.step-target.passed{border-color:#57a479;box-shadow:0 0 0 3px #57a47922}.step-input{position:absolute;border:2px solid #286abc;background:white;border-radius:2px;padding:0 5px;min-height:23px;font-size:clamp(10px,1.3vw,15px);color:#172d40}.lesson-stage.expanded{max-width:100%;width:100%}.lesson-stage.expanded img{max-height:none;max-width:100%;width:100%}
.feedback{font-size:12px;color:#557996;min-height:21px;margin:13px 0}.feedback.error{color:#b94c35}.feedback.success{color:#3c8460}.step-actions,.video-actions{display:flex;align-items:center;flex-wrap:wrap;gap:10px}.step-actions #next-step{margin-left:auto;border-color:#286abc}.step-actions button:disabled{opacity:.45;cursor:default}.video-top{display:flex;align-items:center;gap:10px;justify-content:space-between;margin-top:18px}.video-top h2{font-size:17px}.video-top span{font-size:12px;color:#698299}.lesson-work video{width:100%;max-height:570px;background:#102234;display:block;border-radius:6px}.video-actions{margin:14px 0;font-size:12px}.video-actions select{height:32px}.video-chapters{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:9px}.video-chapters button{text-align:left;font-size:12px;line-height:1.7}.video-chapters small{display:block;color:#8a9aab}#video-state{font-size:12px;color:#65819b}
.lesson-limit{font-size:11px;line-height:1.8;color:#8a9aab;border-top:1px solid #e5ebf2;padding-top:15px;margin-bottom:0}.lesson-complete{background:#eff7f1;border:1px solid #d2e7d9;border-radius:8px;padding:18px;margin-top:20px}.lesson-complete strong{color:#3e7f5b}.lesson-complete p{font-size:12px;color:#6e8b77}.lesson-complete a{margin-right:12px;font-size:12px}.course-tags{display:flex;flex-wrap:wrap;gap:5px;margin-top:9px}.course-tags span{font-size:10px;padding:3px 6px}.method-tags{font-size:11px;line-height:1.8;color:#658ab0;margin-top:5px}.lesson-nav .done-step{color:#398563}.lesson-nav a:hover{background:#f1f6fc}[hidden]{display:none!important}
@media(max-width:850px){.lesson-shell{padding:22px 16px}.lesson-grid{grid-template-columns:1fr}.lesson-nav{padding:14px}.lesson-nav nav{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:5px}.lesson-nav p{margin-bottom:0}.lesson-work{padding:15px}.mode-bar button{padding:7px;font-size:12px}.step-actions button{font-size:12px}.lesson-stage img{max-height:none}.video-top{display:block}.video-chapters{grid-template-columns:1fr}}@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
.lesson-nav .unit-group{display:block;color:#8a9aab;font-size:11px;margin:12px 8px 4px}
.lesson-nav #lesson-units{max-height:430px;overflow-y:auto;scrollbar-width:thin}