.lesson-header-wrap{background:#0b1024;color:white}.lesson-layout{display:grid;grid-template-columns:266px minmax(0,1fr);gap:50px;align-items:start;padding-top:35px;padding-bottom:100px}.lesson-sidebar{border:1px solid #e4e7f0;border-radius:17px;position:sticky;top:20px;overflow:hidden;background:white}.sidebar-top{padding:22px 19px;background:#f6f4ff;border-bottom:1px solid #e4e0f7}.sidebar-top .section-kicker{font-size:10px}.sidebar-top h2{font-size:21px;line-height:1.3;margin:8px 0;letter-spacing:-.04em}.sidebar-top p:last-child{font-size:11px;color:#707792}.lesson-sidebar nav{padding:12px;display:flex;flex-direction:column;gap:5px}.lesson-sidebar-link{width:100%;border:1px solid transparent;border-radius:10px;background:transparent;display:flex;gap:12px;align-items:start;color:#475066;text-align:left;padding:13px 11px;line-height:1.45;font-weight:700;font-size:12px}.lesson-sidebar-link span:first-child{font-size:11px;font-weight:900;color:#8879bb}.lesson-sidebar-link:hover{background:#f6f4ff}.lesson-sidebar-link.active{background:#ede9ff;color:#4c37a0;border-color:#dfd6ff}.sidebar-note{margin:9px 17px 20px;font-size:11px;line-height:1.6;color:#868ca0}.reader-body{min-width:0}.reader-body .course-breadcrumb{margin:3px 0 30px}.reader-heading-row{display:flex;align-items:start;justify-content:space-between;gap:20px;border-bottom:1px solid #e9eaf2;padding-bottom:29px}.reader-heading-row h1{font-size:clamp(33px,3.8vw,51px);letter-spacing:-.06em;line-height:1.12;margin:11px 0 0}.reader-index{font-weight:850;font-size:11px;color:#8b839f}.reader-language{display:flex;background:#f0edff;border:1px solid #e3dcff;border-radius:11px;gap:4px;padding:5px;flex-shrink:0}.reader-language button{border:0;background:transparent;color:#5a5575;padding:10px 14px;border-radius:8px;font-size:12px;font-weight:800}.reader-language button.active{background:#6250ce;color:#fff}.reader-section{padding:35px 0;border-bottom:1px solid #e9eaf2}.reader-section h2{font-size:24px;letter-spacing:-.045em;margin:0 0 17px}.reader-section>p:not(.reader-helper):not(.feedback){font-size:15px;line-height:1.85;color:#5c6577;max-width:760px}.learning-note{display:flex;gap:12px;align-items:start;background:#f2efff;border-left:3px solid #8370ee;border-radius:9px;padding:17px 20px;margin-top:23px}.learning-note>span{font-size:19px;color:#7c60dc}.learning-note p{margin:0;font-size:13px;color:#493e79;line-height:1.7}.section-topline{display:flex;align-items:center;justify-content:space-between;gap:13px;margin-bottom:17px}.section-topline h2{margin:0}.utility-action{border:1px solid #d8d4e9;background:white;color:#6551c7;border-radius:9px;padding:9px 13px;font-size:11px;font-weight:800}.lesson-code{background:#131a32;color:#bee9cf;padding:24px;border-radius:13px;overflow:auto;font-size:12px;line-height:1.95;font-family:ui-monospace,SFMono-Regular,Consolas,monospace;white-space:pre}.reader-helper{font-size:11px;color:#737d90;line-height:1.7}.practice-badge{background:#f0edff;border-radius:6px;color:#5a47ad;font-size:10px;letter-spacing:.06em;font-weight:900;padding:6px 9px}.editor-label{display:block;font-size:12px;font-weight:850;color:#30394e;margin:20px 0 9px}#practice-editor{display:block;width:100%;min-height:190px;resize:vertical;background:#171d34;border:1px solid #4c5572;color:#c9eedb;border-radius:12px;padding:17px;font-family:ui-monospace,SFMono-Regular,Consolas,monospace;font-size:12px;line-height:1.7}#practice-editor:focus-visible{outline:3px solid #917af9;outline-offset:3px}.editor-actions{display:flex;gap:12px;flex-wrap:wrap;margin:18px 0}.feedback{font-size:12px;color:#49417a;min-height:25px;font-weight:700}.quiz-options{padding:0;border:0;margin:22px 0}.quiz-options legend{font-size:12px;color:#667088;margin-bottom:10px}.quiz-options>div{display:grid;gap:9px}.quiz-options label{display:flex;align-items:center;gap:11px;padding:13px 16px;border:1px solid #e1e4ee;border-radius:10px;font-size:13px;cursor:pointer}.quiz-options label:has(input:checked){background:#f0ecff;border-color:#a59ae2}.quiz-options input{accent-color:#7454e9}.lesson-nav-footer{display:flex;justify-content:space-between;gap:14px;margin-top:35px}.lesson-nav-footer button:disabled{opacity:.45;cursor:not-allowed;transform:none}.missing-course[hidden],#lesson-content[hidden]{display:none}
@media(max-width:1000px){.lesson-layout{gap:24px;grid-template-columns:226px minmax(0,1fr)}.reader-heading-row{flex-direction:column}.reader-language{align-self:flex-start}}
@media(max-width:730px){.lesson-layout{grid-template-columns:1fr;gap:23px;padding-top:20px}.lesson-sidebar{position:static}.lesson-sidebar nav{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:6px}.lesson-sidebar-link{font-size:11px;padding:10px 8px;flex-direction:column;gap:4px}.sidebar-top{padding:15px}.sidebar-top h2{font-size:18px}.sidebar-note{margin:4px 14px 12px}.reader-body .course-breadcrumb{margin:3px 0 20px}.reader-section{padding:29px 0}}
@media(max-width:430px){.lesson-sidebar nav{grid-template-columns:1fr}.lesson-sidebar-link{flex-direction:row}.reader-heading-row h1{font-size:34px}.lesson-nav-footer{flex-direction:column}.lesson-nav-footer .button{width:100%}.section-topline{align-items:start;flex-direction:column}.editor-actions{flex-direction:column}.editor-actions .button{width:100%}}
@media(prefers-reduced-motion:reduce){.lesson-sidebar-link{scroll-behavior:auto}}

/* Contextual language setting stays within the reader, not the public header. */
.reader-language-area{display:flex;flex-direction:column;align-items:flex-end;gap:8px;flex-shrink:0}
.reader-settings-link{font-size:11px;font-weight:800;color:#6050b4;text-decoration:underline;text-underline-offset:3px}
@media(max-width:1000px){.reader-language-area{align-items:flex-start}}