:root{--ink:#18201c;--muted:#58645d;--line:#d9e1dc;--surface:#f3f6f4;--white:#fff;--green:#176b49;--green-dark:#0e4f35;--green-soft:#e5f2eb;--coral:#b63f34;--coral-soft:#fff0ed;--amber:#815700;--amber-soft:#fff4d8;--focus:#176b49;--shadow:0 14px 32px #18201c14;color-scheme:light;font-synthesis:none;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif}*{box-sizing:border-box}html{scroll-padding-top:88px}body{color:var(--ink);background:var(--white);margin:0;font-size:16px;line-height:1.6}a{color:inherit}a:focus-visible{outline:3px solid var(--focus);outline-offset:3px}.skip-link{z-index:100;color:var(--white);background:var(--green-dark);padding:10px 14px;position:fixed;top:8px;left:8px;transform:translateY(-160%)}.skip-link:focus{transform:translateY(0)}.container{width:min(1180px,100% - 40px);margin-inline:auto}.site-header{z-index:20;border-bottom:1px solid var(--line);background:var(--white);position:sticky;top:0}.header-inner{justify-content:space-between;align-items:center;gap:18px;min-height:72px;display:flex}.brand{color:var(--ink);align-items:center;gap:12px;font-size:.94rem;font-weight:750;text-decoration:none;display:inline-flex}.brand-mark{border:1px solid var(--green-dark);width:36px;height:36px;color:var(--white);background:var(--green);letter-spacing:0;border-radius:4px;place-items:center;font-size:.66rem;display:grid}.level-label,.eyebrow,.nav-label,.scenario-focus,.task-label{letter-spacing:0;text-transform:uppercase;font-size:.74rem;font-weight:800}.level-label{color:var(--muted);flex:none}.topic-nav{border:1px solid var(--line);background:var(--surface);border-radius:6px;gap:3px;min-width:0;padding:3px;display:flex}.topic-nav a{color:var(--muted);white-space:nowrap;border:1px solid #0000;border-radius:4px;flex:none;padding:7px 10px;font-size:.76rem;font-weight:750;line-height:1.25;text-decoration:none}.topic-nav a:hover{color:var(--green-dark)}.topic-nav a[aria-current=page]{border-color:var(--line);color:var(--green-dark);background:var(--white)}.hero{border-bottom:1px solid var(--line);padding:72px 0 56px}.hero-grid{grid-template-columns:minmax(0,1.65fr) minmax(260px,.75fr);align-items:end;gap:72px;display:grid}.eyebrow{color:var(--green);margin:0 0 12px}h1,h2,h3,p{overflow-wrap:anywhere}h1,h2,h3{letter-spacing:0;margin-top:0;line-height:1.16}h1{max-width:820px;margin-bottom:22px;font-size:clamp(2.45rem,5vw,4.8rem);font-weight:790}.hero-copy{max-width:760px;color:var(--muted);margin:0;font-size:1.14rem}.course-facts{border-top:2px solid var(--ink);margin:0}.course-facts div{border-bottom:1px solid var(--line);grid-template-columns:90px 1fr;gap:16px;padding:12px 0;display:grid}.course-facts dt{color:var(--muted);font-size:.8rem}.course-facts dd{margin:0;font-weight:700}.mobile-scenario-nav{border-bottom:1px solid var(--line);background:var(--surface);display:none}.case-band{color:var(--ink);background:var(--surface);border-bottom:1px solid var(--line);padding:56px 0}.section-heading{grid-template-columns:minmax(0,1fr) minmax(280px,.8fr);align-items:end;gap:64px;display:grid}.section-heading h2{margin-bottom:0;font-size:clamp(1.7rem,3vw,2.55rem)}.section-heading>p{color:var(--muted);margin:0}.metric-grid{grid-template-columns:repeat(3,1fr);gap:16px;margin-top:36px;display:grid}.metric-grid-four{grid-template-columns:repeat(4,minmax(0,1fr))}.metric{border:1px solid var(--line);background:var(--white);border-top-width:4px;border-radius:6px;min-width:0;padding:20px}.metric p,.metric span{color:var(--muted);margin:0;font-size:.82rem;display:block}.metric strong{margin:8px 0 4px;font-size:clamp(1.35rem,2.2vw,2rem);line-height:1.2;display:block}.metric-positive{border-top-color:var(--green)}.metric-negative{border-top-color:var(--coral)}.metric-warning{border-top-color:var(--amber)}.performance-plot{border:1px solid var(--line);background:var(--white);margin:18px 0 0;padding:22px}.performance-plot figcaption{text-transform:uppercase;margin-bottom:16px;font-size:.78rem;font-weight:800}.plot-row{grid-template-columns:84px 1fr 64px;align-items:center;gap:14px;margin-top:10px;font-size:.82rem;display:grid}.plot-row strong{text-align:right}.plot-track{background:#e7ece9;border-radius:3px;height:9px;overflow:hidden}.plot-track span{height:100%;display:block}.plot-positive .plot-track span{background:var(--green)}.plot-negative .plot-track span{background:var(--coral)}.plot-warning .plot-track span{background:var(--amber)}.data-note{color:var(--muted);margin:16px 0 0;font-size:.78rem}.research-signals{border-top:1px solid var(--line);border-bottom:1px solid var(--line);grid-template-columns:repeat(3,minmax(0,1fr));margin-top:34px;display:grid}.research-signals section{border-right:1px solid var(--line);min-width:0;padding:20px 24px}.research-signals section:first-child{padding-left:0}.research-signals section:last-child{border-right:0;padding-right:0}.research-signals h3{color:var(--green-dark);text-transform:uppercase;margin-bottom:7px;font-size:.76rem}.research-signals p{color:var(--muted);margin:0;font-size:.88rem}.learning-layout{grid-template-columns:230px minmax(0,1fr);align-items:start;gap:72px;padding-top:72px;padding-bottom:80px;display:grid}.desktop-scenario-nav{position:sticky;top:94px}.nav-label{color:var(--muted);margin:0 0 14px}.desktop-scenario-nav ol,.mobile-scenario-nav ol{margin:0;padding:0;list-style:none}.desktop-scenario-nav li{border-top:1px solid var(--line)}.desktop-scenario-nav li:last-child{border-bottom:1px solid var(--line)}.desktop-scenario-nav a{color:var(--muted);grid-template-columns:28px 1fr;gap:9px;padding:13px 0;font-size:.82rem;line-height:1.35;text-decoration:none;display:grid}.desktop-scenario-nav a:hover{color:var(--green)}.desktop-scenario-nav a span{color:var(--green);font-weight:800}.scenario{border-bottom:2px solid var(--ink);margin-bottom:72px;padding-bottom:72px;scroll-margin-top:88px}.scenario-header{grid-template-columns:64px minmax(0,1fr);gap:20px;margin-bottom:28px;display:grid}.scenario-number{border:1px solid var(--green);width:56px;height:56px;color:var(--green);border-radius:6px;place-items:center;font-size:.9rem;font-weight:850;display:grid}.scenario-focus{color:var(--green);margin:0 0 8px}.scenario h2{margin:0;font-size:clamp(1.85rem,3.5vw,3.15rem)}.context-block{border-top:1px solid var(--line);border-bottom:1px solid var(--line);grid-template-columns:minmax(0,1.2fr) minmax(260px,.8fr);gap:32px;margin-bottom:36px;padding:20px 0;display:grid}.context-block p,.context-block dl{margin:0}.context-block dl{border-left:1px solid var(--line);padding-left:24px}.context-block dt{color:var(--muted);text-transform:uppercase;font-size:.75rem;font-weight:800}.context-block dd{margin:6px 0 0;font-size:.86rem}.related-lessons{border-top:1px solid var(--line);margin-top:18px;padding-top:16px}.related-lessons>p{color:var(--muted);text-transform:uppercase;font-size:.74rem;font-weight:800}.related-lessons ul{gap:6px;margin:8px 0 0;padding:0;list-style:none;display:grid}.related-lessons a{color:var(--green-dark);text-underline-offset:3px;font-size:.84rem;font-weight:700}.scenario h3{text-transform:uppercase;margin-bottom:16px;font-size:1rem}.dialogue-list{counter-reset:turn;border-top:1px solid var(--line);margin:0;padding:0;list-style:none}.dialogue-list li{border-bottom:1px solid var(--line);grid-template-columns:130px minmax(0,1fr);gap:24px;padding:15px 0;display:grid}.speaker{color:var(--green-dark);font-size:.82rem;font-weight:800}.dialogue-list p{margin:0}.language-block{margin-top:38px}.expression-list{border-top:1px solid var(--line);border-left:1px solid var(--line);grid-template-columns:repeat(2,minmax(0,1fr));margin:0;display:grid}.expression-list div{border-right:1px solid var(--line);border-bottom:1px solid var(--line);min-width:0;padding:16px}.expression-list dt{color:var(--green-dark);font-weight:800}.expression-list dd{color:var(--muted);margin:5px 0 0;font-size:.86rem}.speaking-task{border-left:4px solid var(--amber);background:var(--amber-soft);grid-template-columns:84px minmax(0,1fr);align-items:start;gap:24px;margin-top:30px;padding:22px;display:grid}.task-label{border:1px solid var(--amber);min-height:32px;color:var(--amber);background:var(--white);border-radius:4px;place-items:center;display:inline-grid}.speaking-task h3{color:var(--amber);margin:0 0 6px}.speaking-task p{margin:0}.review-section{border:1px solid var(--green);background:var(--green-soft);border-radius:6px;padding:36px}.review-section h2{max-width:680px;margin-bottom:24px;font-size:clamp(1.65rem,3vw,2.5rem)}.review-section ol{grid-template-columns:repeat(2,minmax(0,1fr));gap:14px 28px;margin:0;padding-left:22px;display:grid}.review-section li{padding-left:4px}.final-speaking-task{border-top:1px solid #176b4957;margin-top:26px;padding-top:24px}.final-speaking-task h3{color:var(--green-dark);margin-bottom:8px}.final-speaking-task p{margin:0}.lesson-bridge{border-top:2px solid var(--ink);border-bottom:1px solid var(--line);grid-template-columns:minmax(0,1fr) auto;align-items:center;gap:48px;margin-top:40px;padding:36px 0;display:grid}.lesson-bridge h2{margin-bottom:10px;font-size:clamp(1.55rem,2.8vw,2.3rem)}.lesson-bridge p:last-child{max-width:670px;color:var(--muted);margin:0}.lesson-bridge>a{border:1px solid var(--green-dark);min-height:44px;color:var(--white);background:var(--green);border-radius:4px;align-items:center;padding:9px 15px;font-size:.86rem;font-weight:800;text-decoration:none;display:inline-flex}.lesson-bridge>a:hover{background:var(--green-dark)}.lesson-navigation{border-top:2px solid var(--ink);border-bottom:1px solid var(--line);margin-top:40px}.lesson-navigation a{gap:4px;padding:24px 0;text-decoration:none;display:grid}.lesson-navigation a:hover strong{color:var(--green)}.lesson-navigation span{color:var(--muted);text-transform:uppercase;font-size:.74rem;font-weight:800}.lesson-navigation strong{font-size:1.05rem}.site-footer{color:var(--white);background:var(--ink)}.footer-inner{justify-content:space-between;align-items:center;gap:24px;min-height:112px;display:flex}.footer-inner p{color:#dce4df;margin:0;font-size:.84rem}.footer-inner a{color:var(--white);flex:none;font-size:.84rem}@media (width<=920px){.level-label{display:none}.hero-grid,.section-heading,.context-block{grid-template-columns:1fr;gap:28px}.hero{padding-top:56px}.course-facts{grid-template-columns:repeat(3,1fr);display:grid}.course-facts div{border-right:1px solid var(--line);padding-right:12px;display:block}.course-facts div:last-child{border-right:0}.course-facts dd{margin-top:3px}.metric-grid-four{grid-template-columns:repeat(2,minmax(0,1fr))}.research-signals{grid-template-columns:1fr}.research-signals section,.research-signals section:first-child,.research-signals section:last-child{border-right:0;border-bottom:1px solid var(--line);padding:16px 0}.research-signals section:last-child{border-bottom:0}.mobile-scenario-nav{padding:14px 0;display:block}.mobile-scenario-nav .container{justify-content:space-between;align-items:center;gap:16px;display:flex}.mobile-scenario-nav .nav-label{margin:0}.mobile-scenario-nav ol{gap:8px;display:flex}.mobile-scenario-nav a{border:1px solid var(--green);width:34px;height:34px;color:var(--green);border-radius:4px;place-items:center;font-size:.72rem;font-weight:800;text-decoration:none;display:grid}.learning-layout{grid-template-columns:1fr;padding-top:56px}.desktop-scenario-nav{display:none}.context-block dl{border-top:1px solid var(--line);border-left:0;padding:20px 0 0}}@media (width<=680px){html{scroll-padding-top:0}.container{width:min(100% - 28px,1180px)}.site-header{position:static}.header-inner{flex-wrap:wrap;gap:9px;min-height:58px;padding:10px 0}.brand{font-size:.82rem}.brand-mark{width:32px;height:32px}.level-label{display:none}.topic-nav{scrollbar-width:thin;width:100%;overflow-x:auto}.hero{padding:42px 0 38px}h1{font-size:2.45rem}.hero-copy{font-size:1rem}.course-facts{grid-template-columns:1fr}.course-facts div{border-right:0;grid-template-columns:78px 1fr;display:grid}.case-band{padding:42px 0}.metric-grid{grid-template-columns:1fr;gap:10px}.metric-grid-four{grid-template-columns:1fr}.metric{grid-template-columns:1fr auto;align-items:center;gap:2px 14px;padding:15px 16px;display:grid}.metric strong{text-align:right;grid-area:1/2/span 2;margin:0}.performance-plot{padding:16px}.plot-row{grid-template-columns:68px 1fr 56px;gap:8px}.mobile-scenario-nav .container{flex-direction:column;align-items:flex-start}.learning-layout{padding-top:44px;padding-bottom:56px}.scenario{margin-bottom:52px;padding-bottom:52px;scroll-margin-top:16px}.scenario-header{grid-template-columns:44px minmax(0,1fr);gap:12px}.scenario-number{width:40px;height:40px}.scenario h2{font-size:1.9rem}.context-block{margin-bottom:28px}.dialogue-list li{grid-template-columns:1fr;gap:4px;padding:13px 0}.expression-list{grid-template-columns:1fr}.speaking-task{grid-template-columns:1fr;gap:14px;padding:18px}.task-label{width:68px}.review-section{padding:24px 20px}.review-section ol{grid-template-columns:1fr}.lesson-bridge{grid-template-columns:1fr;gap:22px;padding:30px 0}.lesson-bridge>a{justify-content:center}.footer-inner{flex-direction:column;justify-content:center;align-items:flex-start;padding:24px 0}}