:root{--bg:#faf8f5;--sidebar-bg:#f3efe9;--card-bg:#fff;--text:#2c2416;--text-secondary:#5c5347;--text-muted:#81776a;--accent:#c75b39;--accent-soft:#f2e4dc;--positive:#2d6a4f;--positive-bg:#edf6f1;--border:#e5ded6;--radius:10px;--sidebar-width:272px;--shadow:0 1px 3px #00000007,0 4px 16px #00000007;--serif:'Songti SC','STSong','SimSun',serif;--sans:-apple-system,BlinkMacSystemFont,'Segoe UI','PingFang SC','Microsoft YaHei',sans-serif}
*{box-sizing:border-box}html{scroll-behavior:auto;scroll-padding-top:28px}body{margin:0;background:var(--bg);color:var(--text);font:15px/1.8 var(--sans);-webkit-font-smoothing:antialiased}button,input{font:inherit}a{color:inherit;text-decoration:none}button,a,input,summary,label{touch-action:manipulation}button{cursor:pointer}a:focus-visible,button:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid var(--accent);outline-offset:4px}button:disabled{cursor:default}.skip-link{position:fixed;left:20px;top:-100px;background:var(--card-bg);padding:12px;z-index:300}.skip-link:focus{top:12px}[hidden]{display:none!important}
.sidebar{position:fixed;inset:0 auto 0 0;width:var(--sidebar-width);background:var(--sidebar-bg);border-right:1px solid var(--border);z-index:100;display:flex;flex-direction:column}.sidebar-header{padding:29px 22px 23px;border-bottom:1px solid var(--border)}.brand{display:block;font:700 19px/1.5 var(--serif)}.brand em{font-style:normal;color:var(--accent)}.brand-sub{margin:7px 0 0;color:var(--text-muted);font-size:11px;letter-spacing:.08em}.sidebar-nav{flex:1;overflow:auto;padding:13px 0 24px}.nav-heading{display:flex;align-items:center;gap:10px;padding:16px 21px 7px;color:var(--text-muted);font-size:11px;font-weight:700;letter-spacing:.08em}.nav-heading:after{content:'';height:1px;flex:1;background:var(--border)}.sidebar-nav a{display:flex;gap:12px;align-items:baseline;min-height:38px;padding:7px 18px 7px 24px;border-left:3px solid transparent;color:var(--text-secondary);font-size:13px;line-height:1.65}.sidebar-nav a:hover{background:#c75b3909;color:var(--accent)}.sidebar-nav a[aria-current=page]{color:var(--accent);background:#c75b3912;border-left-color:var(--accent);font-weight:700}.nav-num{color:var(--text-muted);min-width:19px;font-size:10px;letter-spacing:.03em}.sidebar-note{padding:16px 23px;border-top:1px solid var(--border);font-size:11px;line-height:1.9;color:var(--text-muted)}
.menu-toggle{display:none;position:fixed;top:13px;left:13px;z-index:200;width:42px;height:42px;border-radius:50%;background:var(--card-bg);border:1px solid var(--border);box-shadow:var(--shadow);align-items:center;justify-content:center;flex-direction:column;gap:4px}.menu-toggle span{width:18px;height:2px;background:var(--text);border-radius:1px}.sidebar-overlay{display:none;position:fixed;inset:0;background:#0006;border:0;z-index:99}.main{margin-left:var(--sidebar-width);min-height:100vh}.page-width{width:min(100% - 80px,960px);margin-inline:auto}.hero{text-align:center;padding:70px 30px 46px;position:relative;isolation:isolate;overflow:hidden}.hero:before{content:'';position:absolute;z-index:-1;width:670px;height:620px;top:-180px;left:50%;transform:translateX(-50%);background:radial-gradient(circle,var(--accent-soft),transparent 69%);pointer-events:none}.overline{font-size:11px;color:var(--accent);letter-spacing:.13em;font-weight:500;margin:0 0 20px}.hero h1{font:900 clamp(32px,4vw,49px)/1.35 var(--serif);margin:0 0 20px}.hero h1 em{font-style:normal;color:var(--accent)}.hero-description{max-width:540px;margin:0 auto;color:var(--text-secondary);font-size:15px;font-weight:300;line-height:1.95}.hero-counts{display:flex;justify-content:center;gap:25px;margin:24px 0 0;color:var(--text-muted);font-size:12px}.hero-counts strong{font:700 19px var(--serif);color:var(--accent);margin-right:4px}.actions{display:flex;justify-content:center;gap:12px;flex-wrap:wrap;margin-top:26px}.button{display:inline-flex;align-items:center;justify-content:center;gap:12px;padding:10px 19px;min-height:44px;border:1px solid var(--accent);border-radius:5px;background:var(--accent);color:#fff;font-size:13px;font-weight:500}.button:hover{background:#ae4d2e}.button.secondary{background:transparent;color:var(--accent);border-color:var(--border)}.button.secondary:hover{background:var(--accent-soft)}.hero-divider{width:40px;height:2px;background:var(--accent);margin:34px auto 0}
.section{margin:43px 0 56px}.section-heading{display:flex;justify-content:space-between;align-items:baseline;gap:20px;border-bottom:2px solid #bd795d;padding-bottom:12px;margin-bottom:25px}.section-title{display:flex;align-items:baseline;gap:15px;margin:0;font:700 clamp(23px,2.6vw,30px)/1.5 var(--serif)}.section-kicker{font:500 11px var(--sans);color:var(--accent);white-space:nowrap}.text-link{color:var(--accent);font-size:12px;white-space:nowrap}.text-link:hover{text-decoration:underline}.topic-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:17px}.topic-card{position:relative;padding:23px 25px;background:var(--card-bg);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);transition:border-color .18s,transform .18s}.topic-card:hover{border-color:#c39279;transform:translateY(-2px)}.topic-card .index{font:700 36px/1 var(--serif);color:var(--accent-soft);position:absolute;right:22px;top:23px}.topic-card h3{font:700 20px/1.5 var(--serif);margin:0 44px 7px 0}.topic-card p{color:var(--text-secondary);font-size:13px;line-height:1.85;margin:0 0 13px;max-width:34em}.topic-card .topic-meta{font-size:11px;color:var(--text-muted)}.topic-card .arrow{color:var(--accent);position:absolute;bottom:20px;right:23px}.feature{display:grid;grid-template-columns:1fr auto;align-items:center;gap:35px;padding:33px 36px;background:var(--card-bg);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow)}.feature .eyebrow{color:var(--accent);font-size:11px;margin:0 0 8px}.feature h3{font:700 27px/1.5 var(--serif);margin:0 0 12px}.feature p{margin:0 0 19px;color:var(--text-secondary);font-size:13px;max-width:36em}.feature .feature-number{font:900 83px/1 var(--serif);color:var(--accent-soft);text-align:center}.feature-number small{display:block;font:12px var(--sans);color:var(--text-muted);margin-top:16px}.feature .button{font-size:12px;padding:8px 15px}.resource-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px}.resource-card{display:flex;flex-direction:column;background:var(--card-bg);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);padding:25px;position:relative}.resource-card:hover{border-color:#c39279}.resource-top{display:flex;align-items:center;justify-content:space-between;gap:10px;color:var(--text-muted);font-size:11px}.resource-index{font-family:var(--serif);font-weight:600;color:var(--accent)}.resource-card h2,.resource-card h3{font:700 22px/1.5 var(--serif);margin:12px 0 2px;overflow-wrap:anywhere}.resource-card h2 a:hover,.resource-card h3 a:hover{color:var(--accent)}.english-title{color:var(--text-muted);font-size:11px;line-height:1.7;margin:0 0 13px}.resource-author{font-size:11px;color:var(--text-secondary);margin:0 0 13px}.resource-description{color:var(--text-secondary);font-size:13px;line-height:1.9;margin:0 0 22px}.resource-bottom{display:flex;gap:12px;justify-content:space-between;align-items:center;margin-top:auto;padding-top:15px;border-top:1px dashed var(--border)}.tag-list{display:flex;gap:6px;flex-wrap:wrap}.tag{font-size:10px;background:#f5f1eb;color:var(--text-secondary);padding:2px 7px;border-radius:3px}.tag.green{color:var(--positive);background:var(--positive-bg)}.resource-list{display:flex;flex-direction:column}.article-row{display:grid;grid-template-columns:38px 1fr auto;gap:15px;padding:25px 0;border-bottom:1px solid var(--border)}.article-row:first-child{padding-top:8px}.article-row .index{font:700 28px/1.4 var(--serif);color:#dfc4b5}.article-row h2,.article-row h3{font:700 20px/1.6 var(--serif);margin:0 0 4px}.article-row h2 a:hover,.article-row h3 a:hover{color:var(--accent)}.article-row p{margin:7px 0 10px;color:var(--text-secondary);font-size:13px}.article-row .article-meta{color:var(--text-muted);font-size:11px}.article-row .text-link{align-self:center}.reading-question{padding-left:12px;border-left:2px solid #dbc4b3;color:var(--text-muted);font-size:12px;margin-top:12px}.site-footer{margin-top:72px;padding:29px 0 37px;border-top:1px solid var(--border);display:flex;justify-content:space-between;gap:15px;color:var(--text-muted);font-size:11px}.site-footer a:hover{color:var(--accent)}
.breadcrumb{font-size:11px;color:var(--text-muted);padding-top:31px}.breadcrumb a:hover{color:var(--accent)}.breadcrumb span{margin-inline:9px;color:#b9ab9b}.page-header{padding:30px 0 30px}.page-header .overline{margin-bottom:9px}.page-header h1{font:900 clamp(30px,3.7vw,42px)/1.4 var(--serif);margin:0 0 13px;overflow-wrap:anywhere}.page-header .intro{font-size:14px;max-width:47em;color:var(--text-secondary);margin:0;line-height:1.95}.page-header .english-title{font-size:14px;margin:-1px 0 15px}.page-header .actions{justify-content:flex-start;margin-top:23px}.filter-panel{margin:5px 0 26px;padding:22px 24px;background:#f3efe9;border:1px solid var(--border);border-radius:var(--radius)}.search-field{display:flex;align-items:center;gap:10px}.search-field label{font-size:12px;color:var(--text-secondary);white-space:nowrap}.search-field input{width:100%;min-width:0;padding:10px 13px;background:var(--card-bg);border:1px solid #d7cbbb;border-radius:5px;font-size:13px;color:var(--text);min-height:44px}.filter-bottom{display:flex;justify-content:space-between;align-items:center;gap:15px;flex-wrap:wrap;margin-top:15px}.filter-buttons{display:flex;gap:6px;flex-wrap:wrap}.filter-buttons button{border:1px solid transparent;background:transparent;color:var(--text-secondary);padding:6px 10px;border-radius:4px;font-size:11px;min-height:36px}.filter-buttons button[aria-pressed=true]{color:var(--accent);border-color:#d9b39e;background:#fffaf5}.result-count{font-size:11px;color:var(--text-muted)}.empty-state{text-align:center;padding:54px 25px;background:var(--card-bg);border:1px solid var(--border);border-radius:var(--radius)}.empty-state h2{font:700 23px var(--serif)}.empty-state p{color:var(--text-secondary);font-size:13px}.detail-meta{display:flex;gap:13px;flex-wrap:wrap;color:var(--text-muted);font-size:12px;margin:19px 0 0}.detail-meta span+span{border-left:1px solid var(--border);padding-left:13px}.guide-note{font-size:11px;color:var(--text-muted);margin-top:18px}.point-list{display:grid;gap:18px}.point{background:var(--card-bg);border:1px solid var(--border);border-radius:var(--radius);padding:26px;display:grid;grid-template-columns:43px 1fr;gap:15px;box-shadow:var(--shadow)}.point .index{font:700 32px/1.3 var(--serif);color:#dfc4b5}.point h3{font:700 21px/1.55 var(--serif);margin:0 0 8px}.point p{margin:0;color:var(--text-secondary);font-size:14px}.practice{background:var(--positive-bg);border:1px solid #b7d8c5;border-radius:var(--radius);padding:27px 30px}.practice .eyebrow{font-size:11px;color:var(--positive);font-weight:700;margin:0 0 9px}.practice h2{font:700 24px/1.6 var(--serif);margin:0 0 10px}.practice p{font-size:14px;color:var(--text-secondary);margin:0}.next-reading{display:flex;justify-content:space-between;gap:20px;padding:23px 0;border-top:1px solid var(--border);margin-top:38px;color:var(--accent);font-size:13px}.roadmap-intro{display:flex;justify-content:space-between;gap:20px;align-items:center;background:var(--card-bg);padding:23px 26px;border:1px solid var(--border);border-radius:var(--radius);margin:6px 0 30px}.roadmap-intro p{margin:0;font-size:12px;color:var(--text-secondary)}.roadmap-intro strong{color:var(--accent)}.roadmap-intro progress{display:block;max-width:100%;width:180px;height:6px;accent-color:var(--accent);margin-top:8px}.reset-progress{background:none;border:1px solid var(--border);border-radius:4px;padding:7px 11px;font-size:11px;color:var(--text-secondary);min-height:36px}.roadmap-stage{margin-bottom:28px;background:var(--card-bg);border:1px solid var(--border);border-radius:var(--radius);padding:29px 31px;box-shadow:var(--shadow)}.stage-top{display:flex;align-items:baseline;gap:16px;margin-bottom:10px}.stage-number{font:700 36px/1 var(--serif);color:#dfc4b5}.stage-top h2{font:700 26px/1.5 var(--serif);margin:0}.roadmap-stage>p{margin:0 0 20px;color:var(--text-secondary);font-size:14px}.stage-links{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:20px}.stage-links a{font-size:12px;color:var(--accent);padding:5px 10px;border:1px solid var(--border);border-radius:4px}.stage-links a:hover{background:var(--accent-soft)}.check-task{display:flex;align-items:flex-start;gap:11px;font-size:13px;border-top:1px dashed var(--border);padding-top:17px;color:var(--text-secondary);cursor:pointer}.check-task input{width:18px;height:18px;accent-color:var(--accent);margin:4px 0 0;flex-shrink:0}.check-task:has(input:checked){color:var(--positive)}.local-note{font-size:11px;color:var(--text-muted);margin-top:8px}.topic-question{padding:22px 25px;border-left:3px solid var(--accent);background:#f4ece4;color:var(--text-secondary);font-size:14px;margin:0 0 32px}.topic-question strong{color:var(--text);font-weight:500}.topic-question p{margin:5px 0 0}
/* Keep the source palette while giving small text and controls stronger contrast. */
:root{--text-muted:#756b5f;--accent-ink:#ad4b2e}
.overline,.section-kicker,.text-link,.resource-index,.feature .eyebrow,.filter-buttons button[aria-pressed=true],.sidebar-nav a[aria-current=page],.sidebar-nav a:hover,.stage-links a,.next-reading,.hero-counts strong{color:var(--accent-ink)}
.button{background:var(--accent-ink);border-color:var(--accent-ink)}.button.secondary{background:transparent;color:var(--accent-ink);border-color:var(--border)}.button.secondary:hover{background:var(--accent-soft)}
@media(min-width:1500px){.page-width{max-width:1000px}.hero{padding-top:85px}}
@media(max-width:1050px){.page-width{width:calc(100% - 48px)}.topic-card{padding:21px}.feature{padding:28px}.hero{padding-top:62px}.resource-card{padding:22px}.article-row{grid-template-columns:30px 1fr;gap:12px}.article-row>.text-link{grid-column:2}}
@media(max-width:900px){.sidebar{transform:translateX(-100%);transition:transform .22s ease}.sidebar.open{transform:translateX(0)}.sidebar.open~.main{pointer-events:none}.sidebar-overlay.show{display:block}.menu-toggle{display:flex}.main{margin-left:0}.sidebar-header{padding-top:65px}.hero{padding-top:70px}.page-width{width:calc(100% - 64px);max-width:800px}.breadcrumb{padding-top:74px}.sidebar-note{padding-bottom:max(18px,env(safe-area-inset-bottom))}}
@media(max-width:600px){.page-width{width:calc(100% - 36px)}.hero{padding:75px 20px 24px}.hero h1{font-size:34px;line-height:1.4}.hero-description{font-size:14px;max-width:25em}.hero-counts{gap:20px;margin-top:21px}.hero-counts strong{font-size:18px}.hero .actions{gap:9px}.hero .button{padding:10px 15px;font-size:12px}.hero-divider{margin-top:27px}.section{margin:32px 0 38px}.section-heading{gap:10px;margin-bottom:20px}.section-title{font-size:25px;gap:10px}.section-kicker{font-size:10px}.topic-grid,.resource-grid{grid-template-columns:1fr}.topic-card{padding:22px 23px}.topic-card h3{font-size:21px}.feature{grid-template-columns:1fr;padding:27px 24px;gap:10px}.feature h3{font-size:26px}.feature-number{display:none}.resource-card h2,.resource-card h3{font-size:23px}.resource-card{padding:25px 23px}.site-footer{margin-top:44px;flex-direction:column;gap:7px;padding-block:24px}.page-header{padding-top:24px}.page-header h1{font-size:34px}.page-header .intro{font-size:14px}.filter-panel{padding:18px}.search-field{display:block}.search-field label{display:block;margin-bottom:8px}.filter-bottom{gap:9px}.filter-buttons{gap:2px}.filter-buttons button{padding:7px 8px}.article-row h2,.article-row h3{font-size:21px}.article-row{grid-template-columns:28px 1fr;padding-block:23px}.point{padding:24px 20px;grid-template-columns:30px 1fr;gap:10px}.point .index{font-size:27px}.point h3{font-size:21px}.point p{font-size:13px}.practice{padding:24px}.next-reading{font-size:12px}.roadmap-stage{padding:25px 23px}.stage-top{gap:13px}.stage-top h2{font-size:24px}.stage-number{font-size:31px}.roadmap-intro{padding:20px;align-items:flex-start}.roadmap-intro progress{width:150px}.reset-progress{font-size:10px;white-space:nowrap}.topic-question{padding:19px 21px}.text-link{font-size:11px}.resource-bottom .text-link{font-size:12px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*:before,*:after{transition:none!important;animation:none!important}}

.lesson-toc{padding:24px 28px;background:var(--sidebar-bg);border:1px solid var(--border);border-radius:10px;margin-top:27px}.lesson-toc h2{font:700 21px var(--serif);margin:0 0 15px}.lesson-toc ol{display:grid;grid-template-columns:1fr 1fr;gap:10px 30px;padding-left:22px;margin:0;font-size:13px;color:var(--accent-ink)}.lesson-toc a:hover{text-decoration:underline}.lesson{padding:29px 31px;background:#fff;border:1px solid var(--border);border-radius:10px;box-shadow:var(--shadow);scroll-margin-top:25px}.lesson h3{font:700 24px/1.6 var(--serif);margin:0}.lesson-explain{font-size:14px;color:var(--text-secondary);margin:14px 0 23px;line-height:1.95}.lesson-examples{display:grid;grid-template-columns:1fr 1fr;gap:15px}.lesson-examples>div{padding:18px 20px;border:1px solid;border-radius:7px}.lesson-good{background:#edf6f1;border-color:#b7d8c5!important}.lesson-bad{background:#fef0f0;border-color:#f5c6c6!important}.lesson-examples h4{font-size:12px;margin:0 0 9px}.lesson-good h4{color:#2d6a4f}.lesson-bad h4{color:#9b2226}.lesson-examples p{font-size:13px;line-height:1.95;margin:0;color:var(--text-secondary)}.lesson-exercise{margin:24px 0 16px;border-top:1px dashed var(--border);padding-top:17px}.lesson-exercise summary{font-size:13px;color:var(--accent-ink);cursor:pointer}.lesson-exercise p{font-size:14px;line-height:1.95;color:var(--text-secondary);background:#faf8f5;padding:17px 20px;border-radius:5px}@media(max-width:600px){.lesson-toc{padding:23px}.lesson-toc ol{grid-template-columns:1fr;gap:12px}.lesson{padding:24px 21px}.lesson h3{font-size:23px}.lesson-examples{grid-template-columns:1fr}.lesson .stage-top{align-items:flex-start}.lesson .stage-number{padding-top:6px}}

/* Reading flow: fewer global choices, clearer local state. */
.sidebar-nav .nav-group{margin:15px 0;border-block:1px solid var(--border);padding:6px 0}.nav-group summary{padding:10px 23px;color:var(--text-secondary);font-size:12px;cursor:pointer;min-height:44px}.nav-group summary:hover{color:var(--accent-ink)}.nav-book-title{font:700 19px/1.6 var(--serif);margin:6px 23px}.nav-book-progress{font-size:11px;color:var(--positive);margin:0 23px 12px}.sidebar-nav .nav-book-chapter{font-size:12px;min-height:42px}.sidebar-nav a[aria-current=location]{background:#c75b3912;border-left-color:var(--accent);color:var(--accent-ink)}.hero{padding-block:53px 29px}.hero h1{font-size:clamp(32px,4vw,47px)}.hero .actions{margin-top:23px}.hero-counts{margin-top:20px}.home-search{max-width:490px;margin:25px auto 0;text-align:left}.home-search label{font-size:11px;color:var(--text-secondary);display:block;margin-bottom:7px}.home-search>div{display:flex;background:#fff;border:1px solid #d7cbbb;border-radius:6px;overflow:hidden}.home-search input{width:100%;min-width:0;border:0;padding:11px 13px;background:transparent;font-size:13px;color:var(--text);min-height:46px}.home-search button{border:0;border-left:1px solid var(--border);color:var(--accent-ink);background:#f3efe9;padding:10px 18px;white-space:nowrap;font-size:12px}.resume-reading{display:flex;justify-content:space-between;align-items:center;gap:20px;padding:19px 25px;border:1px solid #b7d8c5;background:var(--positive-bg);border-radius:8px;margin:28px 0}.resume-reading span{color:var(--positive);font-size:11px}.resume-reading p{font:700 19px/1.6 var(--serif);margin:2px 0}.card-progress{font-size:11px;color:var(--positive);margin:0 0 10px}.card-progress:empty{display:none}.study-progress{display:flex;justify-content:space-between;gap:20px;align-items:center;border:1px solid var(--border);background:var(--sidebar-bg);padding:21px 25px;border-radius:8px;margin-top:24px}.study-progress strong{font-size:13px;color:var(--positive);font-weight:500}.study-progress progress{display:block;width:220px;max-width:100%;height:7px;accent-color:var(--positive);margin:10px 0}.study-actions{display:flex;align-items:center;gap:15px;flex-wrap:wrap;justify-content:flex-end}.lesson-toc{background:transparent;margin-block:20px;padding:20px 24px}.lesson{box-shadow:none}.lesson-explain{font-size:16px;max-width:66ch}.lesson-cases{margin:15px 0}.lesson-cases summary{font-size:14px;color:var(--accent-ink);cursor:pointer;padding:9px 0;min-height:44px}.lesson-cases[open] summary{margin-bottom:12px}.lesson-exercise summary{font-size:14px;padding:8px 0;min-height:44px}.lesson-examples p{font-size:14px}.lesson-exercise{margin-block:8px 16px;padding-top:8px}.lesson-footer{display:flex;justify-content:space-between;gap:15px;align-items:center;border-top:1px solid var(--border);padding-top:13px}.complete-lesson{display:flex;gap:10px;align-items:center;cursor:pointer;min-height:44px;font-size:12px;color:var(--text-secondary)}.complete-lesson input{width:21px;height:21px;accent-color:var(--positive);margin:0}.lesson.is-complete{box-shadow:inset 3px 0 var(--positive)}.lesson.is-complete .complete-lesson{color:var(--positive)}.feedback-toast{position:fixed;bottom:22px;right:22px;max-width:calc(100% - 44px);display:flex;gap:17px;align-items:center;z-index:220;padding:15px 19px;color:#fff;background:#2c342d;border-radius:7px;box-shadow:0 4px 20px #0002;font-size:13px}.feedback-toast button{border:0;background:transparent;color:#bfe5c9;padding:8px 2px;font-size:12px;min-height:40px}.feedback-toast [data-feedback-dismiss]{color:#e7e4db}.nav-group summary:focus-visible{outline:3px solid var(--accent);outline-offset:-4px}
@media(max-width:900px){.sidebar-header{padding-top:65px}.study-actions{justify-content:flex-start}.feedback-toast{bottom:15px;right:15px;max-width:calc(100% - 30px)}}
@media(max-width:600px){.hero{padding:73px 20px 20px}.hero h1{font-size:33px}.home-search{margin-top:23px}.hero-divider{margin-top:26px}.study-progress{display:block;padding:19px 21px}.study-actions{margin-top:15px;gap:16px}.study-progress progress{width:100%}.lesson-toc{padding:21px}.lesson-explain{font-size:15px}.lesson-footer{flex-wrap:wrap}.resume-reading{align-items:flex-start;flex-direction:column;gap:12px;padding:20px}.resume-reading .button{width:100%}.feedback-toast{gap:12px;padding:10px 13px;flex-wrap:wrap}.feedback-toast span{flex:1;min-width:130px}.sidebar-nav a{min-height:44px}.filter-buttons button{min-height:44px}.site-footer a{display:inline-block;padding-block:7px}}

.lesson-toc>summary{font:700 19px/1.6 var(--serif);cursor:pointer;min-height:34px}.lesson-toc[open]>summary{margin-bottom:17px}.page-width:has([data-book-study]) .page-header{padding-bottom:8px}.page-width:has([data-book-study]) .detail-meta{margin-top:8px}.lesson-toc summary:focus-visible{outline:3px solid var(--accent);outline-offset:4px}

/* Keep completion controls in place while feedback changes. */
.lesson-footer{display:grid;grid-template-columns:minmax(0,1fr)44px auto;gap:8px;min-height:58px}
.complete-lesson{min-width:0}.complete-lesson span{white-space:nowrap}
.lesson-undo{width:44px;min-height:44px;border:0;background:transparent;color:var(--accent-ink);font-size:12px;padding:0}
.lesson-undo:disabled{color:var(--text-muted);opacity:.5}
.lesson-cases summary,.lesson-exercise summary{touch-action:manipulation}