header{position:sticky;top:0;z-index:30;background:#faf9f5;max-width:1600px;height:88px;padding:0 32px;gap:15px}header nav{margin-left:auto}.app-shell{display:grid;grid-template-columns:280px minmax(0,1fr);max-width:1600px;margin:auto;align-items:start}.app-shell main{min-width:0;max-width:1240px;width:100%;padding:32px 36px 0;margin:0 auto}.lesson-sidebar{position:sticky;top:88px;height:calc(100dvh - 88px);background:#f2f4eb;border-right:1px solid #e0e5d6;display:flex;flex-direction:column;padding:27px 15px 14px;min-width:0}.sidebar-heading{display:flex;align-items:center;justify-content:space-between;padding:0 12px}.sidebar-heading h2{font:900 25px Nunito,sans-serif;letter-spacing:-.6px;margin:7px 0 0}.sidebar-heading .eyebrow{font-size:8px;letter-spacing:1.5px}.sidebar-intro{font-size:11px;line-height:1.7;color:#7d8972;padding:0 12px;margin:12px 0 20px}.lesson-sidebar nav{display:block;overflow:auto;overscroll-behavior:contain;scrollbar-width:thin;scrollbar-color:#c4cfb8 transparent;min-height:0;flex:1;padding:2px 4px 12px}.nav-subject-group{margin-bottom:11px}.nav-subject{display:flex;align-items:center;gap:11px;border:1px solid transparent;border-radius:12px;background:transparent;text-align:left;width:100%;padding:13px 10px;font:800 15px Nunito,sans-serif}.nav-subject small{font:400 9px 'DM Sans',sans-serif;display:block;color:#829374;margin-top:4px}.nav-subject[aria-expanded=true]{background:#e1e9d8;border-color:#d3dfc6;color:#31583f}.nav-icon{font-size:21px}.nav-chevron{margin-left:auto;font:600 17px 'DM Sans',sans-serif;flex-shrink:0;color:#8a9a7d}.nav-sources{margin-top:7px}.nav-sources[hidden],.nav-lessons[hidden]{display:none}.nav-source{display:flex;align-items:center;gap:8px;text-align:left;min-height:46px;width:100%;padding:10px 9px;border:0;border-radius:9px;background:none;font-size:11px;line-height:1.6}.nav-source[aria-expanded=true]{color:#276b57;font-weight:700;background:#eaf0e2}.source-number{display:grid;place-items:center;flex-shrink:0;width:23px;height:23px;background:#e3e9da;border-radius:7px;font-size:10px;color:#7c8d6b}.nav-source[aria-expanded=true] .source-number{background:#276b57;color:white}.nav-lessons{margin:6px 0 10px 19px;border-left:1px solid #d8e1cf;padding-left:7px}.nav-lesson{display:flex;align-items:center;gap:7px;text-align:left;width:100%;min-height:46px;border:1px solid transparent;border-radius:9px;background:transparent;padding:9px 7px;font-size:11px;line-height:1.5}.nav-lesson>span:nth-child(2){flex:1;min-width:0;overflow-wrap:anywhere}.nav-lesson small{display:block;font-size:9px;color:#98a18b;margin-top:3px}.nav-lesson:hover,.nav-source:hover{background:#e6eddd}.nav-lesson[aria-current]{background:#fff;border-color:#c4d7b9;box-shadow:0 2px 4px #334a2a08;color:#276b57;font-weight:700}.lesson-marker{font-size:22px;color:#a6b69a;min-width:13px;text-align:center}.lesson-marker.is-complete{font-size:12px;color:#367c53}.lesson-play{color:#95a58a;font-size:15px}.sidebar-footer{margin:10px 10px 0;padding-top:15px;border-top:1px solid #dfe6d6;font-size:10px;color:#879778}.menu-toggle,#menu-close{display:none;border:1px solid #dde4d5;border-radius:9px;width:39px;height:39px;background:#f2f5ea;font-size:19px;flex-shrink:0}.sidebar-backdrop{display:none}.app-shell .hero{min-height:330px}.app-shell .hero-copy{padding:30px;width:60%}.app-shell .hero h2{font-size:36px}.app-shell .illustration{transform:scale(.82);transform-origin:15% 50%}.app-shell .cards{grid-template-columns:repeat(3,minmax(0,1fr))}.app-shell .card h3{min-height:50px}.source-heading{scroll-margin-top:108px}#source-title:focus{outline:none}@media(min-width:1450px){.app-shell .cards{grid-template-columns:repeat(4,minmax(0,1fr))}.app-shell .hero h2{font-size:41px}.app-shell .illustration{transform:scale(.95)}}@media(min-width:981px) and (max-width:1180px){.app-shell{grid-template-columns:250px minmax(0,1fr)}.app-shell main{padding:25px}.app-shell .cards{grid-template-columns:repeat(2,minmax(0,1fr))}.app-shell .hero-copy{width:65%;padding:25px}.app-shell .hero h2{font-size:31px}.app-shell .illustration{transform:scale(.65);transform-origin:0% 50%}.app-shell .hello h1{font-size:25px}.app-shell .hello p{font-size:12px}.app-shell .source-heading{align-items:start;flex-direction:column}}
@media(max-width:980px){header{height:76px;padding:0 20px;gap:10px}.menu-toggle{display:block}header .brand{font-size:20px}header .logo{font-size:31px}header .tag{display:none}.app-shell{display:block}.app-shell main{padding:28px 25px 0}.lesson-sidebar{position:fixed;top:0;left:0;bottom:0;z-index:110;width:min(320px,88vw);height:100dvh;padding-top:27px;transform:translateX(-100%);visibility:hidden;transition:transform .2s,visibility .2s;box-shadow:15px 0 60px #243e3622}.sidebar-open .lesson-sidebar{transform:translateX(0);visibility:visible}.sidebar-open{overflow:hidden}#menu-close{display:block}.sidebar-backdrop:not([hidden]){display:block;position:fixed;inset:0;z-index:100;background:#1d382b66;backdrop-filter:blur(3px);border:0;width:100%;height:100%}.app-shell .hero-copy{width:58%}.app-shell .illustration{transform:scale(.82)}.app-shell .cards{grid-template-columns:repeat(3,minmax(0,1fr))}.source-heading{scroll-margin-top:95px}}
@media(max-width:650px){header{padding:0 13px;gap:8px}header .brand{font-size:16px;letter-spacing:-.6px}header .logo{font-size:25px}header nav{gap:7px}header nav button{font-size:10px;padding:4px 0}.menu-toggle{width:34px;height:34px;font-size:17px}.app-shell main{padding:25px 20px 0}.app-shell .cards{grid-template-columns:repeat(2,minmax(0,1fr))}.app-shell .hero{min-height:440px}.app-shell .hero-copy{width:100%;padding:28px 24px}.app-shell .hero h2{font-size:35px}.app-shell .illustration{position:absolute;width:390px;bottom:0;right:0;transform:scale(.5);transform-origin:100% 100%}.app-shell .hero-note{max-width:160px;line-height:1.6}.hello h1{font-size:22px}.app-shell .card h3{min-height:44px}.app-shell .tip{padding:15px}}
@media(prefers-reduced-motion:reduce){.lesson-sidebar{transition:none}}