:root{color-scheme:light;--blue-700:#1d4ed8;--blue-600:#2563eb;--blue-500:#3b82f6;--blue-100:#dbeafe;--blue-50:#eff6ff;--ink:#0f172a;--ink-soft:#475569;--muted:#64748b;--line:#dbe3ef;--surface:#fff;--background:#f6f9fe;--success:#0f9f75;--shadow:0 10px 35px #1e40af14;--radius-lg:20px;--radius-md:14px;--shell:1160px}:root[data-theme=dark]{color-scheme:dark;--blue-700:#93c5fd;--blue-600:#60a5fa;--blue-500:#3b82f6;--blue-100:#193767;--blue-50:#142642;--ink:#eff6ff;--ink-soft:#cbd5e1;--muted:#94a3b8;--line:#263b5e;--surface:#101d33;--background:#091426;--success:#5eead4;--shadow:0 12px 40px #00000038}*{box-sizing:border-box}html{scroll-behavior:smooth;background:var(--background);scroll-padding-top:150px}body{color:var(--ink);background:radial-gradient(circle at 10% -10%, #3b82f61f, transparent 27rem), var(--background);-webkit-font-smoothing:antialiased;margin:0;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Noto Sans SC,Microsoft YaHei,sans-serif;font-size:16px;line-height:1.75}a{color:inherit;text-decoration:none}button,input{font:inherit}button{color:inherit}img{max-width:100%;display:block}.shell{width:min(calc(100% - 40px), var(--shell));margin-inline:auto}.skip-link{z-index:100;color:#fff;background:var(--blue-600);border-radius:8px;padding:.65rem 1rem;position:fixed;top:-4rem;left:1rem}.skip-link:focus{top:1rem}.environment-banner{z-index:60;color:#fff;letter-spacing:.04em;text-align:center;background:#1e40af;padding:6px 14px;font-size:12px;font-weight:600;position:relative}.site-header{z-index:50;border-bottom:1px solid color-mix(in srgb, var(--line) 80%, transparent);background:color-mix(in srgb, var(--background) 88%, transparent);backdrop-filter:blur(18px);position:sticky;top:0}.header-inner{align-items:center;gap:28px;min-height:74px;display:flex}.brand{align-items:center;gap:11px;margin-right:auto;line-height:1.15;display:flex}.brand-mark{color:#fff;background:var(--blue-600);border-radius:11px;place-items:center;width:38px;height:38px;font-size:20px;font-weight:700;display:grid;box-shadow:0 7px 18px #2563eb3b}.brand strong,.brand small{display:block}.brand strong{letter-spacing:-.02em}.brand small{color:var(--muted);letter-spacing:.08em;margin-top:5px;font-size:11px}.site-nav{align-items:center;gap:5px;display:flex}.site-nav a{color:var(--ink-soft);border-radius:9px;padding:7px 12px;font-size:14px;font-weight:500}.site-nav a:hover,.site-nav a.active{color:var(--blue-700);background:var(--blue-50)}.icon-button{border:1px solid var(--line);background:var(--surface);cursor:pointer;border-radius:10px;place-items:center;width:39px;height:39px;padding:0;display:grid}.theme-toggle svg,.help-button svg{fill:none;stroke:currentColor;stroke-linecap:round;stroke-linejoin:round;stroke-width:1.8px;width:18px}.moon-icon,[data-theme=dark] .sun-icon{display:none}[data-theme=dark] .moon-icon{display:block}.nav-toggle{display:none}.nav-toggle span{background:currentColor;width:17px;height:1.5px;margin:2px 0;display:block}main{min-height:calc(100vh - 230px)}.section{padding-block:72px}.section-tight{padding-block:44px}.eyebrow{color:var(--blue-600);letter-spacing:.12em;text-transform:uppercase;margin:0 0 12px;font-size:13px;font-weight:700}.section-heading{max-width:680px;margin-bottom:30px}.section-heading h1,.section-heading h2{letter-spacing:-.045em;margin:0;font-size:clamp(30px,4vw,44px);line-height:1.2}.section-heading p{color:var(--ink-soft);margin:13px 0 0}.hero{padding:86px 0 72px;position:relative;overflow:hidden}.hero:after{content:"";right:max(-120px, calc((100vw - var(--shell)) / 2 - 120px));pointer-events:none;border:1px solid #3b82f621;border-radius:50%;width:430px;height:430px;position:absolute;top:35px;box-shadow:inset 0 0 0 70px #3b82f606,inset 0 0 0 140px #3b82f606}.hero-grid{z-index:1;grid-template-columns:1.3fr .7fr;align-items:center;gap:70px;display:grid;position:relative}.hero h1{letter-spacing:-.06em;max-width:780px;margin:0;font-size:clamp(42px,6.4vw,74px);line-height:1.08}.hero h1 span{color:var(--blue-600)}.hero-copy{max-width:610px;color:var(--ink-soft);margin:22px 0 30px;font-size:18px}.hero-search{border:1px solid var(--line);background:var(--surface);max-width:620px;box-shadow:var(--shadow);border-radius:15px;padding:7px;display:flex}.hero-search svg{fill:none;width:20px;stroke:var(--muted);stroke-width:2px;margin-left:12px}.hero-search input{min-width:0;color:var(--ink);background:0 0;border:0;outline:0;flex:1;padding:10px 12px}.hero-search button,.primary-button{color:#fff;background:var(--blue-600);cursor:pointer;border:0;border-radius:10px;padding:10px 18px;font-weight:600}.hero-search button:hover,.primary-button:hover{background:var(--blue-700)}.hero-stats{grid-template-columns:repeat(2,1fr);gap:12px;display:grid}.stat-card{border:1px solid var(--line);border-radius:var(--radius-md);background:color-mix(in srgb, var(--surface) 90%, transparent);padding:22px}.stat-card strong{color:var(--blue-600);font-size:30px;line-height:1;display:block}.stat-card span{color:var(--muted);margin-top:9px;font-size:13px;display:block}.category-grid{grid-template-columns:repeat(3,1fr);gap:16px;display:grid}.category-card{border:1px solid var(--line);border-radius:var(--radius-lg);background:var(--surface);padding:25px;transition:all .2s;position:relative;overflow:hidden}.category-card:before{content:"";background:var(--blue-500);opacity:0;width:4px;transition:all .2s;position:absolute;inset:0 auto 0 0}.category-card:hover{border-color:var(--blue-500);box-shadow:var(--shadow);transform:translateY(-3px)}.category-card:hover:before{opacity:1}.category-icon{width:43px;height:43px;color:var(--blue-600);background:var(--blue-50);border-radius:12px;place-items:center;margin-bottom:30px;font-weight:700;display:grid}.category-card h3{margin:0;font-size:19px}.category-card p{color:var(--muted);margin:8px 0 18px;font-size:14px}.link-arrow{color:var(--blue-600);font-size:14px;font-weight:600}.resource-grid{grid-template-columns:repeat(3,1fr);gap:16px;display:grid}.resource-card{border:1px solid var(--line);border-radius:var(--radius-lg);background:var(--surface);flex-direction:column;min-height:290px;transition:all .2s;display:flex;overflow:hidden}.resource-card:hover{border-color:color-mix(in srgb, var(--blue-500) 70%, var(--line));box-shadow:var(--shadow);transform:translateY(-2px)}.card-main{flex:1;padding:23px 23px 18px}.card-meta{color:var(--muted);align-items:center;gap:9px;font-size:12px;display:flex}.category-chip{color:var(--blue-700);background:var(--blue-50);border-radius:6px;padding:3px 8px;font-weight:600}.resource-card h3{letter-spacing:-.02em;margin:21px 0 9px;font-size:21px;line-height:1.35}.resource-card p{color:var(--ink-soft);margin:0;font-size:14px;line-height:1.75}.tag-row{color:var(--muted);flex-wrap:wrap;gap:8px;margin-top:17px;font-size:12px;display:flex}.card-actions{border-top:1px solid var(--line);color:var(--muted);justify-content:space-between;align-items:center;padding:13px 20px;font-size:12px;display:flex}.text-action{color:var(--muted);cursor:pointer;background:0 0;border:0;align-items:center;gap:5px;padding:4px 7px;display:flex}.text-action:hover,.text-action[aria-pressed=true]{color:var(--blue-600)}.text-action svg{fill:none;stroke:currentColor;stroke-linejoin:round;stroke-width:1.7px;width:16px}.text-action[aria-pressed=true] svg{fill:currentColor}.is-client-hidden{display:none!important}.empty-state{border:1px dashed var(--line);border-radius:var(--radius-lg);color:var(--muted);text-align:center;padding:50px 20px}.library-hero{padding:58px 0 30px}.library-tools{z-index:20;border-block:1px solid var(--line);background:color-mix(in srgb, var(--background) 92%, transparent);backdrop-filter:blur(14px);padding:12px 0;position:sticky;top:74px}.search-bar{align-items:center;gap:10px;display:flex}.search-field{flex:1;position:relative}.search-field svg{fill:none;width:19px;stroke:var(--muted);stroke-width:2px;position:absolute;top:50%;left:14px;transform:translateY(-50%)}.search-field input{width:100%;height:44px;color:var(--ink);border:1px solid var(--line);background:var(--surface);border-radius:11px;outline:none;padding:0 15px 0 44px}.search-field input:focus{border-color:var(--blue-500);box-shadow:0 0 0 3px var(--blue-100)}.filter-row{scrollbar-width:none;gap:7px;display:flex;overflow-x:auto}.filter-button{white-space:nowrap;border:1px solid var(--line);background:var(--surface);cursor:pointer;border-radius:9px;padding:9px 13px}.filter-button[aria-pressed=true]{color:#fff;border-color:var(--blue-600);background:var(--blue-600)}.results-head{justify-content:space-between;align-items:center;margin-bottom:19px;display:flex}.results-head h2{margin:0;font-size:20px}.results-head span{color:var(--muted);font-size:13px}.breadcrumb{color:var(--muted);gap:8px;padding-top:32px;font-size:13px;display:flex}.breadcrumb a:hover{color:var(--blue-600)}.article-hero{border-bottom:1px solid var(--line);padding:34px 0 42px}.article-hero h1{letter-spacing:-.05em;max-width:800px;margin:13px 0 14px;font-size:clamp(36px,5vw,56px);line-height:1.15}.article-hero .lead{max-width:740px;color:var(--ink-soft);margin:0;font-size:17px}.article-meta{flex-wrap:wrap;gap:9px;margin-top:22px;display:flex}.article-meta span{border:1px solid var(--line);color:var(--muted);background:var(--surface);border-radius:7px;padding:5px 10px;font-size:12px}.study-toolbar{z-index:30;border-bottom:1px solid var(--line);background:color-mix(in srgb, var(--surface) 94%, transparent);backdrop-filter:blur(14px);position:sticky;top:74px}.toolbar-inner{justify-content:space-between;align-items:center;gap:20px;min-height:61px;display:flex}.reveal-control,.learning-actions{align-items:center;gap:6px;display:flex}.toolbar-label{color:var(--muted);margin-right:7px;font-size:12px}.reveal-control button,.learning-actions button{cursor:pointer;background:0 0;border:1px solid #0000;border-radius:8px;align-items:center;gap:6px;padding:7px 11px;font-size:13px;display:flex}.reveal-control button:hover,.learning-actions button:hover{background:var(--blue-50)}.reveal-control button[aria-pressed=true]{color:var(--blue-700);border-color:var(--blue-100);background:var(--blue-50)}.learning-actions button[aria-pressed=true]{color:var(--blue-700);background:var(--blue-50)}.learning-actions svg{fill:none;stroke:currentColor;stroke-linecap:round;stroke-linejoin:round;stroke-width:1.8px;width:17px}.learning-actions button[aria-pressed=true]:first-child svg{fill:currentColor}.article-layout{grid-template-columns:minmax(0,1fr) 260px;align-items:start;gap:42px;padding-block:38px 80px;display:grid}.study-content{gap:24px;min-width:0;font-size:16px;display:grid}.learning-unit{border:1px solid var(--line);background:var(--surface);border-radius:18px;scroll-margin-top:155px;overflow:hidden;box-shadow:0 8px 30px #1e40af0e}.unit-header{border-bottom:1px solid var(--line);background:linear-gradient(135deg, var(--surface), var(--blue-50));justify-content:space-between;align-items:flex-start;gap:24px;padding:24px 26px 21px;display:flex}.unit-kicker{color:var(--blue-600);letter-spacing:.08em;gap:8px;font-size:11px;font-weight:700;display:flex}.unit-kicker span+span{border-left:1px solid var(--blue-100);padding-left:8px}.unit-heading h2{letter-spacing:-.025em;margin:8px 0 3px;font-size:24px;line-height:1.35}.unit-heading p{color:var(--muted);margin:0;font-size:12px}.unit-header-actions{flex-shrink:0;align-items:flex-end;gap:8px;display:flex}.unit-header-actions label{gap:3px;display:grid}.unit-header-actions label>span{color:var(--muted);font-size:10px}.unit-header-actions select{min-height:38px;color:var(--ink);border:1px solid var(--line);background:var(--surface);border-radius:8px;padding:0 28px 0 10px}.unit-download{min-height:38px;color:var(--blue-700);border:1px solid var(--blue-100);background:var(--blue-50);border-radius:8px;align-items:center;gap:6px;padding:7px 11px;font-size:12px;font-weight:600;display:inline-flex}.unit-download:hover{color:#fff;border-color:var(--blue-600);background:var(--blue-600)}.unit-download svg{fill:none;stroke:currentColor;stroke-linecap:round;stroke-linejoin:round;stroke-width:1.8px;width:16px}.unit-body{padding:24px 27px 28px;font-size:16px}.unit-body>h2{color:var(--ink);border-left:3px solid var(--blue-500);letter-spacing:-.015em;margin:31px 0 13px;padding:8px 0 0 13px;font-size:18px;line-height:1.45}.unit-body>h2:first-child{margin-top:0}.unit-body p{margin:10px 0;position:relative}.unit-body .lang-en{color:var(--ink);font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;font-size:17px;line-height:1.82}.unit-body .lang-zh{color:var(--ink-soft);font-size:15px;line-height:1.85}.unit-body .is-question{color:var(--ink-soft);border-left:3px solid var(--blue-500);background:var(--blue-50);padding:9px 12px;font-size:13px}.bilingual-pair{border:1px solid var(--line);background:color-mix(in srgb, var(--blue-50) 45%, var(--surface));border-radius:12px;grid-template-columns:1fr 1fr;gap:22px;margin:15px 0;padding:17px 18px;display:grid}.bilingual-pair>p{margin:0}.bilingual-pair>.lang-zh{border-left:1px solid var(--line);padding-left:18px}.unit-body ol,.unit-body ul{padding-left:24px}.unit-body li{margin:8px 0;position:relative}.unit-body table{border-collapse:collapse;width:100%;margin:24px 0;display:block;overflow-x:auto}.unit-body td,.unit-body th{border:1px solid var(--line);text-align:left;min-width:140px;padding:10px 12px}.unit-body tr:nth-child(2n){background:var(--blue-50)}.unit-body blockquote{border-left:3px solid var(--blue-500);background:var(--blue-50);margin:20px 0;padding:15px 18px}.unit-body math{max-width:100%}.figure-block{margin:26px 0!important}.figure-block img{border:1px solid var(--line);max-height:560px;box-shadow:var(--shadow);background:#fff;border-radius:12px;margin-inline:auto}.memory-segment{border-radius:5px;transition:background .18s,box-shadow .18s;display:inline;position:relative}.memory-segment+.memory-segment{margin-left:4px}.segment-initials{color:var(--blue-700);letter-spacing:.025em;overflow-wrap:anywhere;font-family:ui-monospace,SFMono-Regular,Menlo,monospace;display:none}.memory-segment.is-active{box-shadow:0 0 0 2px var(--blue-500)}.mode-hide-en .memory-segment:not(.is-revealed),.mode-recall .memory-segment:not(.is-revealed){vertical-align:middle;background:repeating-linear-gradient(135deg, var(--blue-100), var(--blue-100) 8px, color-mix(in srgb, var(--blue-100) 72%, var(--surface)) 8px, color-mix(in srgb, var(--blue-100) 72%, var(--surface)) 16px);cursor:pointer;user-select:none;min-width:116px;min-height:30px;margin-block:2px;padding-inline:8px;display:inline-block}.mode-hide-en .memory-segment:not(.is-revealed) .segment-full,.mode-recall .memory-segment:not(.is-revealed) .segment-full{visibility:hidden}.mode-hide-en .memory-segment:not(.is-revealed):after,.mode-recall .memory-segment:not(.is-revealed):after{content:"点击揭示";color:var(--blue-700);letter-spacing:.05em;place-items:center;font-size:10px;font-weight:700;display:grid;position:absolute;inset:0}.mode-initials .memory-segment:not(.is-revealed) .segment-full{display:none}.mode-initials .memory-segment:not(.is-revealed) .segment-initials{cursor:pointer;display:inline}.mode-recall .lang-zh:not(.is-question,.is-revealed){background:var(--blue-50);cursor:pointer;user-select:none;border-radius:8px;min-height:44px;color:#0000!important}.mode-recall .lang-zh:not(.is-question,.is-revealed):after{content:"显示中文提示";color:var(--blue-700);place-items:center;font-size:11px;font-weight:700;display:grid;position:absolute;inset:0}.unit-controls{border-top:1px solid var(--line);background:var(--blue-50);justify-content:space-between;align-items:center;gap:16px;min-height:58px;padding:10px 20px;display:flex}.sentence-navigation{flex-wrap:wrap;gap:5px;display:flex}.sentence-navigation button{color:var(--ink-soft);border:1px solid var(--line);background:var(--surface);cursor:pointer;border-radius:7px;padding:7px 9px;font-size:11px}.sentence-navigation button:hover{color:var(--blue-700);border-color:var(--blue-500)}.sentence-navigation .reveal-next{color:#fff;border-color:var(--blue-600);background:var(--blue-600)}.unit-progress{color:var(--muted);white-space:nowrap;font-size:11px}.article-toc{border-left:1px solid var(--line);max-height:calc(100vh - 190px);padding-left:20px;position:sticky;top:158px;overflow-y:auto}.article-toc strong{font-size:13px}.article-toc ol{margin:13px 0 0;padding:0;list-style:none}.article-toc a{color:var(--muted);border-radius:7px;grid-template-columns:24px 1fr;gap:6px;padding:6px 8px;font-size:12px;line-height:1.45;display:grid}.article-toc a span{color:color-mix(in srgb, var(--muted) 65%, transparent);font-size:10px}.article-toc a:hover,.article-toc a.is-current{color:var(--blue-700);background:var(--blue-50)}.notice-box{border:1px solid var(--blue-100);border-radius:var(--radius-md);background:var(--blue-50);color:var(--ink-soft);padding:19px 21px;font-size:14px}.notice-box strong{color:var(--blue-700)}.guide-welcome{width:min(100% - 32px,520px);color:var(--ink);border:1px solid var(--blue-100);background:var(--surface);border-radius:22px;padding:34px;box-shadow:0 28px 90px #0f172a47}.guide-welcome::backdrop{backdrop-filter:blur(4px);background:#07122694}.guide-dialog-close{width:34px;height:34px;color:var(--muted);cursor:pointer;background:0 0;border:0;border-radius:50%;font-size:24px;position:absolute;top:13px;right:15px}.guide-dialog-close:hover{background:var(--blue-50)}.guide-dialog-mark{color:#fff;background:linear-gradient(135deg, var(--blue-500), var(--blue-700));border-radius:16px;place-items:center;width:54px;height:54px;margin-bottom:20px;font-size:25px;font-weight:800;display:grid;box-shadow:0 12px 26px #2563eb40}.guide-welcome h2{margin:0;font-size:28px;line-height:1.3}.guide-welcome>p:not(.eyebrow){color:var(--ink-soft);margin:12px 0 24px;font-size:14px}.guide-dialog-actions{align-items:center;gap:10px;display:flex}.guide-dialog-actions button{color:var(--muted);cursor:pointer;background:0 0;border:0;padding:9px 14px}.guide-home .section-heading{max-width:760px}.guide-start-card{color:#fff;background:linear-gradient(120deg,#1d4ed8,#2563eb 58%,#60a5fa);border-radius:20px;justify-content:space-between;align-items:center;gap:32px;margin:35px 0 25px;padding:30px 34px;display:flex;box-shadow:0 16px 40px #2563eb33}.guide-start-card span{letter-spacing:.12em;font-size:11px;font-weight:700}.guide-start-card h2{margin:5px 0 2px;font-size:23px}.guide-start-card p{color:#dbeafe;margin:0;font-size:13px}.guide-start-card .primary-button{color:var(--blue-700);background:#fff;flex-shrink:0}.guide-method-grid{grid-template-columns:repeat(2,1fr);gap:16px;display:grid}.guide-method-grid article{border:1px solid var(--line);background:var(--surface);border-radius:16px;padding:27px}.guide-method-grid article>span{color:var(--blue-500);letter-spacing:.1em;font-size:12px;font-weight:800}.guide-method-grid h2{margin:12px 0 6px;font-size:20px}.guide-method-grid p{color:var(--ink-soft);margin:0;font-size:14px}.guide-tip{color:var(--ink-soft);border:1px solid var(--blue-100);background:var(--blue-50);border-radius:12px;gap:18px;margin-top:18px;padding:17px 20px;font-size:13px;display:flex}.guide-tip strong{color:var(--blue-700);white-space:nowrap}.guide-demo-hero{padding:40px 0 26px}.guide-demo-hero a{color:var(--muted);font-size:13px}.guide-demo-hero .eyebrow{margin-top:24px}.guide-demo-hero h1{margin:0;font-size:clamp(32px,5vw,48px);line-height:1.2}.guide-demo-hero p:last-child{color:var(--muted);margin:8px 0 0}.demo-library{border:1px solid var(--blue-100);background:var(--blue-50);border-radius:12px;align-items:center;gap:8px;margin-bottom:20px;padding:13px 18px;font-size:13px;display:flex}.demo-library strong{color:var(--blue-700)}.demo-toolbar{border-top:1px solid var(--line);top:74px}.guide-demo-stage{padding-block:34px 120px}.tour-overlay{z-index:80;pointer-events:none;background:#07122694;position:fixed;inset:0}.is-tour-focus{border-radius:10px;z-index:82!important;box-shadow:0 0 0 5px white, 0 0 0 9px var(--blue-500), 0 18px 55px #0000004d!important;position:relative!important}.tour-coach{z-index:90;width:min(100% - 32px,390px);color:var(--ink);border:1px solid var(--blue-100);background:var(--surface);border-radius:17px;padding:23px;position:fixed;bottom:28px;right:28px;box-shadow:0 20px 70px #0712264d}.tour-progress,.tour-actions{justify-content:space-between;align-items:center;gap:10px;display:flex}.tour-progress span{color:var(--blue-600);font-size:12px;font-weight:800}.tour-progress button,.tour-actions>button:first-child{color:var(--muted);cursor:pointer;background:0 0;border:0;padding:6px;font-size:12px}.tour-coach h2{margin:17px 0 5px;font-size:21px}.tour-coach p{min-height:48px;color:var(--ink-soft);margin:0 0 18px;font-size:13px}.tour-actions{justify-content:flex-end}.tour-actions .primary-button{min-width:105px}.about-grid{grid-template-columns:1fr 1fr;gap:18px;display:grid}.info-card{border:1px solid var(--line);border-radius:var(--radius-lg);background:var(--surface);padding:26px}.info-card h2{margin:0 0 12px;font-size:20px}.info-card p,.info-card li{color:var(--ink-soft);font-size:14px}.site-footer{border-top:1px solid var(--line);background:var(--surface)}.footer-inner{justify-content:space-between;align-items:center;gap:30px;min-height:156px;display:flex}.footer-inner strong{font-size:15px}.footer-inner p{color:var(--muted);margin:4px 0 0;font-size:12px}.footer-links{color:var(--muted);gap:22px;font-size:13px;display:flex}.footer-links a:hover{color:var(--blue-600)}:focus-visible{outline:3px solid color-mix(in srgb, var(--blue-500) 50%, transparent);outline-offset:2px}@media (width<=900px){.hero-grid{grid-template-columns:1fr;gap:35px}.hero-stats{grid-template-columns:repeat(4,1fr);max-width:500px}.stat-card{padding:16px}.stat-card strong{font-size:24px}.category-grid,.resource-grid{grid-template-columns:repeat(2,1fr)}.article-layout{grid-template-columns:minmax(0,1fr)}.article-toc{display:none}}@media (width<=720px){.shell{width:min(calc(100% - 28px), var(--shell))}.header-inner{min-height:64px}.brand small{display:none}.site-nav{border:1px solid var(--line);background:var(--surface);box-shadow:var(--shadow);border-radius:13px;flex-direction:column;align-items:stretch;padding:10px;display:none;position:absolute;inset:64px 14px auto}.site-nav.is-open{display:flex}.site-nav a{padding:10px 12px}.nav-toggle{order:2;display:block}.theme-toggle{order:1}.help-button{order:0}.hero{padding:60px 0 52px}.hero:after{display:none}.hero h1{font-size:45px}.hero-copy{font-size:16px}.hero-search button{padding-inline:13px}.hero-stats{grid-template-columns:repeat(2,1fr)}.category-grid,.resource-grid,.about-grid{grid-template-columns:1fr}.resource-card{min-height:260px}.section{padding-block:55px}.library-hero{padding-top:40px}.library-tools{top:64px}.search-bar{flex-direction:column;align-items:stretch}.toolbar-inner{flex-direction:column;align-items:stretch;gap:0;width:100%}.reveal-control{padding:9px 14px;overflow-x:auto}.toolbar-label{display:none}.learning-actions{border-top:1px solid var(--line);justify-content:flex-end;padding:6px 14px}.article-layout{padding-top:34px}.study-content{gap:18px}.unit-header{flex-direction:column;align-items:stretch;padding:20px 18px}.unit-header-actions{align-items:stretch}.unit-header-actions label{flex:1}.unit-header-actions select{width:100%}.unit-body{padding:20px 18px 23px}.bilingual-pair{grid-template-columns:1fr;gap:11px;padding:14px}.bilingual-pair>.lang-zh{border-top:1px solid var(--line);border-left:0;padding:10px 0 0}.unit-controls{align-items:flex-end}.sentence-navigation button[data-unit-action=previous],.sentence-navigation button[data-unit-action=next]{display:none}.article-hero h1{font-size:40px}.breadcrumb{padding-top:22px}.footer-inner{flex-direction:column;align-items:flex-start;padding-block:35px}.guide-start-card{flex-direction:column;align-items:flex-start;padding:25px}.guide-method-grid{grid-template-columns:1fr}.guide-tip{flex-direction:column;gap:3px}.tour-coach{bottom:16px;right:16px}}@media (prefers-reduced-motion:reduce){*,:before,:after{scroll-behavior:auto!important;transition:none!important}}@media print{.environment-banner,.site-header,.site-footer,.study-toolbar,.article-toc{display:none!important}body{color:#000;background:#fff}.article-layout{padding-top:20px;display:block}.memory-segment .segment-full{visibility:visible!important;display:inline!important}.memory-segment .segment-initials,.memory-segment:after,.lang-zh:after{display:none!important}}