:root{--ink:#24251f;--muted:#636257;--line:#d5d0c2;--paper:#f5f2ea;--white:#fffefa;--blue:#274f64;--light-blue:#edf3f4;--ochre:#9b5b25;--green:#2f6548;--red:#8a3f35;--reading-size:18px;--ui-size:14px;--touch-size:44px;--measure:780px}
*{box-sizing:border-box}html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}body{margin:0;background:var(--paper);color:var(--ink);font:var(--reading-size)/1.65 Arial,Helvetica,sans-serif}a{color:inherit}.site-nav{min-height:68px;padding:10px clamp(18px,5vw,72px);border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;gap:24px;background:rgba(245,242,234,.98)}.brand img{display:block;width:116px}.nav-links{display:flex;align-items:center;justify-content:flex-end;gap:18px;flex-wrap:wrap}.nav-links>a{display:inline-flex;align-items:center;min-height:var(--touch-size);font-size:var(--ui-size);font-weight:800;text-decoration:none}.support-switch{display:flex;border:1px solid var(--ink)}.support-switch a{display:inline-flex;align-items:center;justify-content:center;min-height:var(--touch-size);padding:7px 11px;font-size:var(--ui-size);font-weight:800;text-decoration:none}.support-switch a[aria-current=page]{background:var(--ink);color:var(--white)}
.hero{padding:clamp(56px,8vw,100px) clamp(20px,8vw,118px);border-bottom:1px solid var(--line);background:linear-gradient(126deg,var(--paper) 0 75%,#ddd5c2 75%)}.hero>span,.study-method>span,.stage-head>span,.grammar-unit section>span,.grammar-unit aside>span{color:var(--blue);font-size:var(--ui-size);font-weight:900;letter-spacing:.13em}.hero h1{max-width:1030px;margin:18px 0 22px;font:clamp(2.8rem,6vw,6rem)/.96 Georgia,"Times New Roman",serif;letter-spacing:-.05em}.hero>p{max-width:850px;margin:0;color:var(--muted);font:var(--reading-size)/1.75 Georgia,"Times New Roman",serif}.hero-actions{display:flex;flex-wrap:wrap;gap:10px;margin-top:28px}.primary,.secondary{display:inline-flex;align-items:center;justify-content:center;min-height:var(--touch-size);padding:12px 17px;border:1px solid var(--ink);font-size:var(--ui-size);font-weight:900;text-decoration:none}.primary{background:var(--ink);color:var(--white)}.progress-card{max-width:600px;margin-top:35px;padding:18px;border:1px solid var(--line);background:rgba(255,254,250,.95)}.progress-card>span{display:block;color:var(--blue);font-size:var(--ui-size);font-weight:900;letter-spacing:.1em}.progress-card>strong{display:block;margin:5px 0 11px}.progress-track{height:8px;background:#ded9cc}.progress-track i{display:block;width:0;height:100%;background:var(--green);transition:width .25s ease}
.study-method{width:min(1180px,calc(100% - 40px));margin:auto;padding:62px 0;display:grid;grid-template-columns:220px minmax(0,1fr);gap:30px;border-bottom:1px solid var(--line)}.study-method h2{margin:0 0 12px;font:clamp(2rem,4vw,3.6rem)/1 Georgia,"Times New Roman",serif;letter-spacing:-.035em}.study-method p{max-width:var(--measure);margin:0;color:var(--muted);font-family:Georgia,"Times New Roman",serif}.stage-nav{width:min(1180px,calc(100% - 40px));margin:45px auto}.stage-nav>strong{display:block;margin-bottom:12px;color:var(--blue);font-size:var(--ui-size);letter-spacing:.12em;text-transform:uppercase}.stage-nav ol{display:grid;grid-template-columns:repeat(4,1fr);gap:1px;margin:0;padding:1px;background:var(--line);list-style:none}.stage-nav a{height:100%;min-height:var(--touch-size);padding:16px;display:grid;grid-template-columns:auto 1fr;gap:5px 12px;background:var(--white);text-decoration:none}.stage-nav a:hover,.stage-nav a:focus-visible{outline:2px solid var(--ink);outline-offset:-2px;background:var(--light-blue)}.stage-nav span{grid-row:1/3;color:var(--ochre);font-family:ui-monospace,SFMono-Regular,Menlo,monospace}.stage-nav strong{font:1rem/1.25 Georgia,"Times New Roman",serif}.stage-nav small{color:var(--muted);font-size:var(--ui-size)}
.grammar-stages{width:min(1000px,calc(100% - 30px));margin:auto}.grammar-stage{scroll-margin-top:18px}.stage-head{padding:70px 0 30px}.stage-head h2{max-width:800px;margin:10px 0 12px;font:clamp(2.4rem,5vw,4.6rem)/.98 Georgia,"Times New Roman",serif;letter-spacing:-.04em}.stage-head p{max-width:var(--measure);margin:0;color:var(--muted);font-family:Georgia,"Times New Roman",serif}.grammar-unit{scroll-margin-top:18px;margin:0 0 55px;border:1px solid var(--line);background:var(--white)}.grammar-unit>header{display:grid;grid-template-columns:70px 1fr;gap:18px;padding:34px clamp(20px,5vw,48px);border-bottom:1px solid var(--line)}.grammar-unit>header>span{color:var(--ochre);font:800 var(--ui-size)/1.5 ui-monospace,SFMono-Regular,Menlo,monospace}.grammar-unit h3{margin:0 0 10px;font:clamp(2rem,4vw,3.2rem)/1 Georgia,"Times New Roman",serif;letter-spacing:-.03em}.grammar-unit header p{max-width:var(--measure);margin:0;color:var(--muted)}.grammar-unit header p strong{display:block;margin-bottom:3px;color:var(--blue);font-size:var(--ui-size);letter-spacing:.08em}.grammar-unit section,.grammar-unit aside{padding:28px clamp(20px,5vw,48px);border-bottom:1px solid var(--line)}.rule p{max-width:var(--measure);margin:10px 0 0;font:1.08rem/1.75 Georgia,"Times New Roman",serif}.lesson-grid{display:grid;grid-template-columns:1fr 1fr}.lesson-grid section{height:100%}.patterns{background:#f0eee7}.patterns ul,.examples ol{margin:14px 0 0;padding:0;list-style:none}.patterns li{margin:8px 0}.patterns code{display:block;padding:10px 12px;border:1px solid var(--line);background:var(--white);font:16px/1.5 ui-monospace,SFMono-Regular,Menlo,monospace;white-space:normal}.examples li{padding:10px 0;border-top:1px solid var(--line)}.examples li:first-child{border-top:0}.examples p{margin:0;font-family:Georgia,"Times New Roman",serif}.examples small{display:block;margin-top:3px;color:var(--muted);font-size:var(--ui-size);line-height:1.5}.contrast{background:#faf7ef}.contrast>div{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin-top:14px}.contrast div p{margin:0;padding:14px;border:1px solid var(--line);background:var(--white)}.contrast b{display:block;margin-bottom:4px;color:var(--muted);font-size:var(--ui-size)}del{color:var(--red);text-decoration-thickness:2px}ins{color:var(--green);font-weight:800;text-decoration:none}.contrast>p{max-width:var(--measure);margin:14px 0 0}.bridge{background:var(--light-blue)}.bridge p{max-width:var(--measure);margin:9px 0 0}.practice{padding:30px clamp(20px,5vw,48px)}.practice fieldset{max-width:var(--measure);margin:0 0 14px;padding:0;border:0}.practice legend{width:100%;margin-bottom:12px;font:1.1rem/1.55 Georgia,"Times New Roman",serif}.practice legend span{display:block;margin-bottom:5px;color:var(--blue);font:900 var(--ui-size)/1.4 Arial,sans-serif;letter-spacing:.12em}.practice label{min-height:var(--touch-size);padding:10px 12px;display:grid;grid-template-columns:24px 1fr;gap:10px;border-top:1px solid var(--line);cursor:pointer}.practice label:has(input:checked){background:var(--light-blue)}.practice input{width:20px;height:20px;margin:2px 0}.practice button{min-height:var(--touch-size);padding:10px 15px;border:1px solid var(--ink);background:var(--ink);color:var(--white);font:800 var(--ui-size)/1.4 Arial,sans-serif;cursor:pointer}.feedback{min-height:25px;margin:12px 0 0;font-size:var(--ui-size);font-weight:800}.feedback[data-state=correct]{color:var(--green)}.feedback[data-state=wrong],.feedback[data-state=warning]{color:var(--red)}.answer-explanation{max-width:var(--measure);margin-top:12px;border:1px solid var(--line)}.answer-explanation summary{min-height:var(--touch-size);padding:10px 13px;cursor:pointer;font-size:var(--ui-size);font-weight:900}.answer-explanation p{margin:0;padding:13px;border-top:1px solid var(--line)}
footer{padding:30px clamp(20px,5vw,70px);display:grid;grid-template-columns:auto 1fr auto;align-items:center;gap:24px;color:var(--muted);font-size:var(--ui-size)}footer img{display:block;width:100px}footer p{margin:0}footer span{text-align:right}
@media(max-width:900px){.stage-nav ol{grid-template-columns:repeat(2,1fr)}.lesson-grid{grid-template-columns:1fr}.hero{background:var(--paper)}}@media(max-width:720px){.site-nav{align-items:flex-start}.nav-links>a{display:none}.study-method{grid-template-columns:1fr;gap:10px}.grammar-unit>header{grid-template-columns:1fr}.contrast>div{grid-template-columns:1fr}footer{grid-template-columns:1fr}footer span{text-align:left}}@media(max-width:480px){.support-switch a{padding-inline:8px}.support-switch a:first-child{display:none}.stage-nav ol{grid-template-columns:1fr}}@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.progress-track i{transition:none}}@media print{.site-nav,.hero-actions,.stage-nav,.practice button{display:none!important}.hero,.stage-head{padding-block:20px;background:#fff}.grammar-unit{break-before:page}.answer-explanation>*{display:block!important}.answer-explanation summary{display:none}}