:root{--ink:#233b38;--muted:#65736e;--accent:#246b58;--line:#dce4dc;--paper:#f6f7f1;--white:#fff;--tint:#e8eee2}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:100px}body{margin:0;background:var(--paper);color:var(--ink);font-family:system-ui,-apple-system,"Segoe UI","Microsoft YaHei",sans-serif;line-height:1.65}a{color:inherit;text-decoration:none}button,input{font:inherit}[hidden]{display:none!important}a:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid #b77521;outline-offset:4px}a:hover{color:var(--accent)}.skip-link{position:absolute;left:16px;top:-80px;background:white;padding:12px;z-index:10}.skip-link:focus{top:12px}.site-header{border-bottom:1px solid var(--line);background:var(--paper)}.header-inner{max-width:1160px;margin:auto;min-height:100px;padding:18px 32px;display:flex;justify-content:space-between;align-items:center;gap:24px}.brand{display:flex;align-items:center;gap:12px;font-size:19px;font-weight:700}.brand-mark{display:grid;place-items:center;background:var(--accent);color:white;width:44px;height:48px;border-radius:12px 12px 12px 2px;font-size:27px}.brand small{display:block;font-size:11px;letter-spacing:1px;color:var(--muted);font-weight:400}.site-header nav{display:flex;gap:28px;font-size:14px}.site-header nav a{padding:8px 0}.site-header [aria-current]{border-bottom:2px solid var(--accent)}.page{max-width:1160px;padding:0 32px 72px;margin:auto}.hero{display:grid;grid-template-columns:1fr 260px;gap:64px;align-items:center;padding:72px 0 60px}.eyebrow{color:var(--accent);font-size:11px;font-weight:700;letter-spacing:2px;margin:0 0 14px}h1,h2,h3,p{margin-top:0}h1{font-size:clamp(29px,4vw,44px);line-height:1.3;letter-spacing:-1px;margin-bottom:20px}h2{font-size:25px;line-height:1.4;margin-bottom:10px}h3{font-size:17px;line-height:1.5;margin-bottom:5px}.hero p:not(.eyebrow){color:var(--muted);font-size:15px;line-height:1.9}.hero-actions{display:flex;align-items:center;gap:26px;margin-top:30px;flex-wrap:wrap}.primary-link{display:inline-flex;gap:26px;background:var(--accent);color:white;padding:13px 22px;border-radius:7px;font-size:14px}.primary-link:hover{background:#184e40;color:white}.text-link{color:var(--accent);font-weight:600;font-size:14px;text-decoration:underline;text-underline-offset:4px}.hero-note{background:var(--tint);border:1px solid #d6dfce;border-radius:72px 72px 8px 8px;padding:48px 22px 30px;text-align:center;transform:rotate(3deg)}.hero-note>span{font-family:Georgia,serif;font-size:32px;color:var(--accent)}.hero-note p{margin:12px 0 25px}.hero-note small{border-top:1px solid #c8d4bf;padding-top:16px;display:block;color:var(--muted);font-size:12px}.library-section{border-top:1px solid var(--line);padding-top:34px;margin-top:24px;margin-bottom:55px}.section-heading{display:flex;justify-content:space-between;align-items:center;gap:20px;margin-bottom:25px}.section-heading p:not(.eyebrow),.family-heading p{color:var(--muted);font-size:14px;margin-bottom:0}.section-count{font-size:12px;color:var(--muted);white-space:nowrap}.collection-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.collection-card{display:flex;align-items:center;gap:14px;padding:23px 18px;border:1px solid var(--line);border-radius:9px;background:white;transition:border-color .15s,box-shadow .15s}.collection-card:hover{border-color:var(--accent);box-shadow:0 4px 16px #233b380c}.collection-card h3{font-size:15px}.collection-card p{font-size:12px;color:var(--muted);margin:0}.book-badge{display:grid;place-items:center;flex:0 0 38px;height:48px;background:#edf2e9;border-left:3px solid #9aaf8c;border-radius:2px 6px 6px 2px;font-family:Georgia,serif;font-size:22px;color:var(--accent)}.arrow{margin-left:auto;color:#7c8d81;font-size:19px}.collection-family{margin-top:30px}.family-heading{display:flex;gap:16px;align-items:baseline;margin-bottom:14px}.family-heading h3{font-size:16px}.breadcrumbs{display:flex;gap:12px;color:var(--muted);font-size:12px;padding:26px 0}.breadcrumbs a{text-decoration:underline}.directory-intro{padding:20px 0 25px}.directory-intro h1{font-size:34px;margin-bottom:12px}.directory-intro p:not(.eyebrow){font-size:14px}.muted{color:var(--muted)}.directory-layout{display:grid;grid-template-columns:180px minmax(0,1fr);gap:40px;margin-top:16px}.directory-aside{align-self:start;position:sticky;top:24px;border-top:1px solid var(--line);padding-top:20px}.directory-aside h2{font-size:13px;color:var(--muted);margin-bottom:14px}.directory-aside nav{display:flex;flex-direction:column;gap:3px}.directory-aside a{padding:7px 10px;border-radius:5px;font-size:13px}.directory-aside a:hover{background:var(--tint)}.search-box{padding:18px 20px;background:#ecefe6;border-radius:8px;margin-bottom:25px}.search-box label{font-size:12px;font-weight:600;display:block;margin-bottom:6px}input[type=search]{width:100%;padding:11px 14px;border:1px solid #c8d3c5;border-radius:5px;color:var(--ink);background:white;font-size:14px;min-height:44px}.search-status{margin:5px 0 0;font-size:12px;color:var(--muted)}.search-status:empty{display:none}.unit-section{margin-bottom:30px;scroll-margin-top:24px}.unit-heading{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:12px}.unit-heading h2{font-size:18px;margin:0}.unit-heading>span{font-size:11px;color:var(--muted)}.lesson-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.lesson-link{display:flex;align-items:center;justify-content:space-between;gap:10px;background:white;border:1px solid var(--line);border-radius:7px;padding:16px 18px;min-height:76px}.lesson-link:hover{border-color:var(--accent);background:#fcfdf9}.lesson-link strong{font-size:14px;font-weight:600}.lesson-link small{display:block;color:var(--muted);font-size:12px;margin-top:3px}.lesson-link>span:last-child{color:var(--accent)}.resume{display:flex;align-items:center;justify-content:space-between;gap:18px;padding:20px 24px;background:#e7eee2;border-left:3px solid var(--accent);border-radius:5px;margin-bottom:32px}.resume small{display:block;color:var(--muted);font-size:11px;margin-bottom:4px}.resume strong{font-size:14px}.resume a{white-space:nowrap}.empty-state{border:1px dashed var(--line);padding:25px;color:var(--muted);text-align:center}.site-footer{border-top:1px solid var(--line);max-width:1096px;margin:auto;padding:25px 0 35px;display:flex;align-items:start;justify-content:space-between;gap:20px;font-size:12px;color:var(--muted)}.support summary{cursor:pointer;min-height:32px}.support img{display:block;max-width:100%;height:auto}.support p{margin-top:12px}
@media(max-width:950px){.collection-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.hero{gap:30px;grid-template-columns:1fr 210px}.directory-layout{grid-template-columns:140px minmax(0,1fr);gap:24px}.site-footer{margin:0 32px}}
@media(max-width:620px){html{scroll-padding-top:20px}.header-inner{min-height:82px;padding:16px 20px;gap:12px}.brand{font-size:16px;gap:8px}.brand small{font-size:9px;letter-spacing:0}.brand-mark{width:34px;height:39px;font-size:22px}.site-header nav{gap:14px;font-size:12px}.site-header nav a{min-height:44px;display:flex;align-items:center}.page{padding:0 20px 35px}.hero{padding:40px 0 35px;display:block}.hero-note{display:none}.hero-actions{gap:20px}.hero p:not(.eyebrow){font-size:14px}.collection-grid{grid-template-columns:1fr}.collection-card{padding:18px}.section-heading{display:block}.section-count{display:block;margin-top:12px}.family-heading{display:block}.family-heading p{font-size:12px}.directory-intro{padding:12px 0}.directory-intro h1{font-size:28px}.directory-layout{display:block}.directory-aside{position:static;margin-bottom:24px;padding-top:15px}.directory-aside nav{flex-direction:row;flex-wrap:wrap;gap:6px}.directory-aside a{background:var(--tint);padding:8px 12px;min-height:40px}.directory-aside h2{margin-bottom:10px}.lesson-grid{gap:8px}.lesson-link{padding:12px;min-height:80px}.lesson-link small{font-size:11px}.unit-heading>span{font-size:10px}.resume{padding:16px;align-items:start;flex-direction:column;gap:10px}.site-footer{margin:0 20px;flex-wrap:wrap}.site-footer>span{flex-basis:100%}.library-section{margin-bottom:35px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{transition:none!important}}
/* Study pages share the collection page shell and color palette. */
.breadcrumbs{flex-wrap:wrap}.study-intro{padding:18px 0 32px}.study-intro h1{font-size:clamp(27px,4vw,36px);margin-bottom:12px}.study-intro .muted{font-size:14px;margin-bottom:18px}.textbook-content{max-width:880px;margin:auto}.study-panel{background:white;border:1px solid var(--line);border-radius:10px;padding:28px;margin-bottom:24px}.panel-heading{display:flex;align-items:center;gap:12px;margin-bottom:16px}.panel-heading h2{font-size:20px;margin:0}.panel-number{color:var(--accent);font-size:12px;background:var(--tint);padding:5px 8px;border-radius:5px}.study-panel p{font-size:13px}.study-panel audio{width:100%;display:block;margin-top:20px}.study-image-link{display:block}.study-image-link img{max-width:100%;height:auto;display:block;margin:auto;border-radius:5px}.study-image-link:focus-visible{outline-offset:6px}.audio-help{font-size:13px;color:var(--muted);margin-bottom:24px}.playback-status{font-size:13px;color:#8a371c}.playback-status:empty{display:none}.study-word-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px;align-items:start}.study-word{min-width:0;background:white;border:1px solid var(--line);border-radius:9px;padding:24px;overflow-wrap:anywhere}.word-number{display:block;color:var(--muted);font-size:11px;margin-bottom:14px;letter-spacing:1px}.word-heading{font-size:24px;color:var(--accent);margin:0 0 12px;line-height:1.5}.word-meaning{font-size:15px;margin:0}.word-example{border-top:1px solid var(--line);padding-top:18px;margin-top:22px}.word-example h3{font-size:11px;color:var(--muted);font-weight:500;margin-bottom:10px;letter-spacing:1px}.example-text{font-size:16px;line-height:1.8;margin-bottom:10px}.example-translation{font-size:13px;color:var(--muted);margin:0;line-height:1.8}.audio-trigger{font:inherit;color:inherit;text-align:left;border:0;padding:2px 0;background:transparent;cursor:pointer;display:inline;min-height:44px;line-height:inherit;border-radius:3px}.audio-trigger:hover{color:var(--accent);text-decoration:underline;text-underline-offset:4px}.audio-trigger:focus-visible{outline:3px solid #b77521;outline-offset:4px}.sound-icon{display:inline-grid;place-items:center;border:1px solid #b6cabb;background:#eff4eb;color:var(--accent);border-radius:50%;width:28px;height:28px;font-size:14px;margin-left:8px;vertical-align:middle;text-decoration:none}.study-word audio{display:none}.lesson-pagination{border-top:1px solid var(--line);margin-top:48px;padding-top:24px;display:grid;grid-template-columns:1fr auto 1fr;gap:24px;align-items:center}.lesson-step{display:flex;flex-direction:column;gap:5px;min-height:52px;font-size:14px}.lesson-step small{font-size:12px;color:var(--accent)}.lesson-step.next{text-align:right}.lesson-boundary{font-size:12px;color:var(--muted)}.lesson-boundary:last-child{text-align:right}
@media(max-width:950px){.study-word-grid{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media(max-width:620px){.study-intro{padding:12px 0 24px}.study-panel{padding:18px;margin-bottom:18px}.study-word-grid{grid-template-columns:1fr;gap:14px}.study-word{padding:22px}.lesson-pagination{gap:16px;grid-template-columns:1fr 1fr}.lesson-pagination>.text-link{grid-column:1/-1;grid-row:2;text-align:center;padding:12px}.lesson-pagination>:last-child{grid-column:2;grid-row:1}.lesson-step{font-size:12px}.breadcrumbs{font-size:11px;gap:8px}.audio-help{font-size:12px}}