:root{--font:"Noto Sans", "Helvetica Neue", Arial, sans-serif;--font-cjk:"PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "微软雅黑", "Noto Sans SC", "Noto Sans CJK SC", sans-serif;--text:#333;--muted:#8a8a8a;--link:#3e99ed;--border:#e4e4e4;--red:#df3142;--red-dark:#ae393f;--surface:#fafafa;--grammar:#bce6dd;--sentence:#f2f2f2;--hover-blue:#4099ed}*,:before,:after{box-sizing:border-box}html{-webkit-text-size-adjust:100%}body{color:var(--text);font-family:var(--font);background:#fff;margin:0;font-size:16px;font-weight:300;line-height:1.5}button{font:inherit;color:inherit;cursor:pointer}img{max-width:100%;display:block}a{color:inherit;text-decoration:none}.du-link{color:var(--link);background:0 0;border:0;padding:0}.du-link:hover{text-decoration:underline}.du-container{width:100%;max-width:1260px;margin:0 auto;padding:0 16px}.du-page{padding-top:66px;padding-bottom:48px}.du-empty{color:var(--muted);padding:24px 0}.du-navbar{z-index:20;background:#fff;border-bottom:1px solid #ccc;height:52px;position:fixed;inset:0 0 auto}.du-navbar-inner{align-items:center;gap:24px;height:100%;display:flex}.du-brand{color:#222;align-items:center;gap:8px;font-size:15px;font-weight:400;display:flex}.du-brand img{width:24px;height:24px}.du-nav-pills{gap:12px;margin:0;padding:0;font-size:14px;font-weight:400;list-style:none;display:flex}.du-nav-pills a,.du-nav-pills span{color:#111;border-radius:999px;padding:3px 14px;display:block}.du-nav-pills a.active{background:var(--red);color:#fff}.du-nav-disabled{opacity:.45;cursor:default}.du-user{margin-left:auto;position:relative}.du-user-toggle{color:#000;background:0 0;border:0;padding:6px}.du-dropdown{border:1px solid var(--border);background:#fff;border-radius:6px;min-width:180px;margin:4px 0 0;padding:6px 0;font-size:14px;list-style:none;position:absolute;top:100%;right:0;box-shadow:0 6px 20px #00000014}.du-dropdown a{padding:6px 16px;display:block}.du-dropdown a:hover{background:#f4f4f4}.du-navbar-slim{height:44px}.du-home-link{margin-left:auto;font-size:13px}.du-lessons{max-width:1080px}.du-top-banner{border:1px solid var(--border);background:linear-gradient(180deg, var(--red), var(--red-dark));height:180px;margin-top:8px;position:relative;overflow:hidden}.du-top-banner-teacher{background:url(/banner-teacher@2x.png) 0 0/181px 155px no-repeat;width:181px;height:155px;position:absolute;bottom:0;left:5%}.du-top-banner h1{color:#fff;text-align:center;margin:0;font-size:46px;font-weight:300;line-height:180px}.du-filter-row{margin:20px 0 8px}.du-filter-top{flex-wrap:wrap;align-items:center;gap:8px 32px;margin-bottom:10px;display:flex}.du-search{width:min(100%,340px);position:relative}.du-search input{width:100%;height:30px;font:inherit;border:0;border-bottom:1px solid #ccc;outline:none;padding:4px 30px 4px 8px;font-size:13px}.du-search input:focus{border-bottom-color:var(--link)}.du-search svg{color:#555;position:absolute;top:9px;right:8px}.du-hide-read{background:0 0;border:0;align-items:center;gap:6px;padding:0;font-size:13px;display:flex}.du-level-filter{flex-wrap:wrap;gap:8px;display:flex}.du-level-chip{text-transform:capitalize;background:#fff;border:1px solid;border-left-width:4px;border-radius:3px;align-items:center;gap:8px;padding:2px 6px 2px 8px;font-size:12px;display:inline-flex}.du-level-chip[aria-pressed=true]{background:#f6f6f6}.du-section{margin-top:18px}.du-section-title{color:#222;align-items:baseline;gap:10px;margin:0 0 12px;font-size:19px;font-weight:400;display:flex}.du-see-more{color:var(--link);font-size:11px}.du-grid{grid-template-columns:repeat(4,minmax(0,1fr));gap:20px 18px;display:grid}.du-card{background:#fff;border:1px solid #eee;flex-direction:column;padding:6px 8px 10px;transition:box-shadow .15s;display:flex;position:relative}.du-card:hover{box-shadow:0 2px 12px #00000014}.du-card-header{justify-content:space-between;align-items:center;height:18px;margin-bottom:4px;display:flex}.du-card-date{color:var(--muted);font-size:9px}.du-card-badge{border:1px solid #c7c7c7;border-radius:50%;place-items:center;width:14px;height:14px;display:grid}.du-card-badge.is-done{color:#63bdab;border:0}.du-card-badge-course{background:#63bdab;border:0;border-radius:3px;width:12px;height:10px;box-shadow:2px -2px 0 -.5px #fff,2px -2px 0 .5px #63bdab}.du-card-image{aspect-ratio:16/10;background:#f2f2f2;overflow:hidden}.du-card-image img{object-fit:cover;width:100%;height:100%}.du-card-title{color:#222;min-height:2.8em;margin-top:8px;font-size:11px;line-height:1.4}.du-card-level{text-align:right;text-transform:uppercase;margin-top:4px;font-size:8px}.du-card-bar{height:3px;position:absolute;inset:auto -1px -1px}.du-more-categories div{flex-wrap:wrap;gap:4px 10px;font-size:12px;display:flex}.du-breadcrumb{color:#404040;margin:14.4px 0;font-size:14.4px}.du-lesson-header{grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:24px;margin-bottom:18px;font-size:18px;display:grid}.du-lesson-level{text-transform:uppercase;font-size:11px}.du-lesson-header-level{color:#404040;text-transform:uppercase;margin-top:12.6px;font-size:12.6px;font-weight:600}.du-level-newbie{color:#fd826e}.du-level-elementary{color:#63bdab}.du-level-intermediate{color:#fdc86c}.du-level-upper-intermediate{color:#3e80af}.du-level-advanced{color:#b18bac}.du-level-master{color:#d9be8f}.du-lesson-title{color:#404040;margin:0 0 .25em;font-size:1.3em;font-weight:700;line-height:1.2}.du-save-button{background:#fafafa;border:1px solid #e4e4e4;align-items:center;gap:.5em;margin:.25em 0;padding:.25em;font-size:14.4px;line-height:20px;display:inline-flex;box-shadow:2px 2px 3px #fafafa}.du-save-star{background:url(/save-star-off.png) 0 0/20px 20px no-repeat;width:20px;height:20px}.du-save-star.is-saved{background-image:url(/save-star-on.png)}.du-progress-label{text-align:right;margin:14px 0 1em;font-size:.8em}.du-progress{background:#f5f5f5;border-radius:4px;height:25px;margin-bottom:.5em;overflow:hidden;box-shadow:inset 0 1px 2px #0000001a}.du-progress-fill{background:#63bdab;height:100%;transition:width .3s}.du-lesson-description{line-height:1.5}.du-lesson-description p{margin:0 0 1rem}.du-lesson-image img{border:1px solid #eee;width:100%}.du-chapters{margin:0;padding:0;list-style:none}.du-chapter{background:var(--surface);border:1px solid #ececec;border-left:6px solid;justify-content:space-between;align-items:center;min-height:56px;margin-bottom:14px;padding:8px 26px 8px 12px;font-size:16px;display:flex}.du-chapter:hover{background:#f3f3f3}.du-chapter.is-soon{color:#b0b0b0;border-left:1px solid #ececec;justify-content:flex-start;gap:8px;padding-left:13px}.du-chapter.is-soon small{font-size:10px}.du-reader-page{padding-bottom:130px}.du-reader-box{border:1px solid #d9d9d9}.du-meaning-row{border-bottom:1px solid #d9d9d9;min-height:68px;padding:6px 17px 10px}.du-meaning-label{color:#aaa;justify-content:space-between;font-size:10px;display:flex}.du-meaning-hide{font-size:10px}.du-meaning-sentence{margin-top:2px;font-size:16px}.du-meaning-word{flex-wrap:wrap;align-items:baseline;gap:4px 12px;margin-top:2px;display:flex}.du-meaning-hanzi{font-family:var(--font-cjk);color:#202020;font-size:22px}.du-meaning-pinyin{font-size:15px}.du-meaning-hsk{border:1px solid;border-radius:3px;padding:0 5px;font-size:10px}.du-meaning-text{flex-basis:100%;font-size:15px}.du-reader{padding:18px 16px 24px;position:relative}.du-reader-tools{justify-content:flex-end;gap:20px;display:flex;position:relative}.du-reader-tools>button{color:#444;background:0 0;border:0;align-items:center;gap:6px;padding:2px 0;font-size:13px;display:inline-flex}.du-reader-tools>button.is-active{color:var(--link)}.du-settings{z-index:5;border:1px solid var(--border);background:#fff;border-radius:6px;width:260px;padding:8px 14px;font-size:13px;position:absolute;top:calc(100% + 6px);right:0;box-shadow:0 8px 24px #0000001a}.du-settings-row{justify-content:space-between;align-items:center;padding:6px 0;display:flex}.du-settings-row button{background:#fff;border:1px solid #ddd;border-radius:3px;margin-left:4px;padding:1px 8px}.du-reader-search{max-width:420px;color:var(--muted);align-items:center;gap:8px;margin:10px 0 0 auto;font-size:13px;display:flex}.du-reader-search input{height:30px;font:inherit;font-family:var(--font-cjk);border:1px solid #ccc;border-radius:3px;flex:1;padding:4px 8px}.du-reader-search button{background:#fff;border:1px solid #ddd;border-radius:3px;padding:2px 8px}.du-reader-loading{text-align:center;padding:80px 0}.du-reader-text{--py:.68em;color:#202020;-webkit-user-select:none;user-select:none;margin:32px 8% 24px;font-family:PingFang SC,Microsoft YaHei,微软雅黑,Noto Sans,Helvetica,sans-serif;font-weight:400;line-height:2.69}.du-reader-text:lang(zh-Hant){font-family:PingFang TC,Microsoft YaHei,微软雅黑,Noto Sans,Helvetica,sans-serif}.rw{vertical-align:bottom;cursor:pointer;margin-bottom:.32em;line-height:1;display:inline-flex}.rw.sym{cursor:default}.rw-space{display:inline-block}.rc{flex-direction:column;align-items:stretch;display:inline-flex}.rp{min-height:calc(var(--py) * 1.3);font-family:Helvetica,Noto Sans,sans-serif;font-size:var(--py);color:#404040;text-align:center;white-space:nowrap;padding:0 2px;line-height:1.3}.rh{text-align:center;padding:.04em 0 .1em;line-height:1.1;display:block}.rh-group{justify-content:center;display:flex}.rg{flex-direction:column;display:inline-flex}.ru{align-self:center;width:.92em;height:2px;margin-top:.14em}.rh-group .ru{align-self:stretch;width:auto;margin-inline:1px}@media (resolution>=2x){.du-reader-text{font-weight:300}.rp{color:#555}}.grammar .rh{background:var(--grammar)}.no-grammar .grammar .rh{background:0 0}.no-hsk .ru{background:0 0!important}.no-pinyin .rp{visibility:hidden}.no-pinyin .rw:hover .rp,.no-pinyin .rw.selected .rp{visibility:visible}.in-sentence .rh,.no-grammar .in-sentence.grammar .rh{background:var(--sentence)}.in-sentence.grammar .rh{background:var(--grammar)}.rw:not(.sym):hover .rh,.rw.hovered .rh,.rw.playing .rh,.rw.selected .rh{color:var(--hover-blue)}.rh.match{background:#ff0!important}.rh.match-current{background:#ff9632!important}.du-mark-read{color:#555;justify-content:flex-end;align-items:center;gap:10px;margin-right:110px;font-size:15px;display:flex}.du-mark-read-toggle{background:#e2e2e2;border:2px solid #c8c8c8;border-radius:50%;place-items:center;width:42px;height:42px;padding:0;display:grid}.du-chapter-nav{border-top:1px solid #d9d9d9;grid-template-columns:1fr auto 1fr;align-items:center;padding:10px 8px;font-size:12px;display:grid}.du-chapter-nav>:last-child{justify-self:end}.du-chapter-nav-center{font-size:17px}.du-copyright{color:#555;text-align:center;margin:18px 0 0;font-size:12px}.du-player{z-index:20;background:#fff;border-top:1px solid #ccc;height:78px;position:fixed;inset:auto 0 0}.du-player-inner{grid-template-columns:1fr auto 1fr;align-items:center;max-width:1260px;height:100%;margin:0 auto;padding:0 16px;display:grid}.du-player-title{font-size:15px}.du-player-controls{align-items:center;gap:24px;display:flex}.du-play{color:#3a7bb8;background:#fff;border:2px solid #c9c9c9;border-radius:50%;place-items:center;width:50px;height:50px;padding:0 0 0 2px;display:grid}.du-play:disabled{opacity:.4;cursor:default}.du-player-toggles{justify-content:flex-end;gap:14px;display:flex}.du-toggle{flex-direction:column;align-items:center;gap:4px;font-size:12px;display:flex}.du-toggle-circle{color:#3a7bb8;background:#fff;border:1.5px solid #c9c9c9;border-radius:50%;place-items:center;width:22px;height:22px;padding:0;font-size:8px;display:grid}.du-toggle-hanzi{font-family:var(--font-cjk);font-size:10px}@media (width<=900px){.du-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.du-lesson-header{grid-template-columns:1fr}.du-lesson-image{order:-1}.du-mark-read{margin-right:0}}@media (width<=600px){.du-nav-pills{display:none}.du-top-banner{height:80px}.du-top-banner-teacher{display:none}.du-top-banner h1{font-size:1.6em;line-height:80px}.du-grid{grid-template-columns:minmax(0,1fr)}.du-player-lesson{display:none}.du-player-inner{grid-template-columns:auto 1fr;gap:12px}}.du-word-menu{z-index:15;flex-direction:column;gap:4px;display:flex;position:absolute;transform:translate(-50%,calc(-100% - 6px))}.du-word-menu-bubble{text-align:left;background:#d9e6f0;border:1px solid #4281b6;border-radius:13px;align-items:center;width:140px;height:40px;margin:0;padding:0 8px;display:flex;box-shadow:0 15px 10px #0000004d}.du-word-menu-bubble.is-grammar{background:#eef9f6;border-color:#58c0a9}.du-word-menu-icon{place-items:center;width:30px;height:30px;display:grid}.du-word-menu-icon img{max-width:26px;max-height:26px}.du-word-menu-title{color:#4d4c53;padding-left:8px;font-size:17px}.du-word-menu-bubble:hover{background:#4281b6}.du-word-menu-bubble.is-grammar:hover{background:#58c0a9}.du-word-menu-bubble:hover .du-word-menu-icon{filter:brightness(0)invert()}.du-word-menu-bubble:hover .du-word-menu-title{color:#fff}.du-panel-backdrop{z-index:40;opacity:0;pointer-events:none;background:#000;transition:opacity .3s;position:fixed;inset:0}.du-panel-backdrop.is-open{opacity:.5;pointer-events:auto}.du-panel{z-index:41;visibility:hidden;background:#fff;border-left:1px solid #0000002e;flex-direction:column;width:min(100%,520px);transition:transform .3s ease-in-out,visibility .3s;display:flex;position:fixed;inset:0 0 0 auto;transform:translate(100%)}.du-panel.is-open{visibility:visible;transform:none}.du-panel-header{padding:0 8px;box-shadow:0 11px 11px #29293617}.du-panel-header-top{justify-content:space-between;align-items:center;padding:16px 8px;display:flex}.du-panel-close{background:0 0;border:0;padding:0}.du-panel-heading{margin:0;font-size:22px;font-weight:400}.du-panel-body{flex:1;padding:0 24px 32px;overflow-y:auto}.du-panel-title{color:#000;margin:16px 0 0;font-size:28px;font-weight:400}.du-hsk-badge{white-space:nowrap;background:#fff;border:1px solid;border-left-width:10px;border-radius:10px;align-items:center;height:30px;padding:4px 10px;font-size:16px;display:inline-flex}.du-spinner{border:3px solid #e4e4e4;border-top-color:#58c0a9;border-radius:50%;width:32px;height:32px;margin:48px auto;animation:.8s linear infinite du-spin}@keyframes du-spin{to{transform:rotate(360deg)}}.grammar-body{color:#1a191c;font-size:17px;font-weight:400;line-height:1.5}.grammar-body h1,.grammar-body h2{color:#000;letter-spacing:.25px;margin:.8em 0;line-height:1.4}.grammar-body h1{font-size:28px;font-weight:400}.grammar-body h2{font-size:20px;font-weight:700}.grammar-body p{margin:0 0 1em}.grammar-body ul{padding-left:1.4em}.grammar-body ul p{margin:.2em 0}.grammar-body img{vertical-align:middle;display:inline-block}.grammar-body .pe-2{padding-right:.5rem}.grammar-body .my-3{margin:1rem 0}.grammar-body .mt-3{margin-top:1rem}.grammar-body .pill{background:#def2ee;border-radius:10px;align-items:center;gap:8px;width:fit-content;padding:8px 12px;font-size:22px;font-weight:400;display:flex}.grammar-body .pill p{font-size:inherit;margin:0}.grammar-body .connect-points .pill{background:#d9e6f0}.grammar-body .common-mistakes .pill{background:#ffe4e1}.grammar-body .heading-info-icon{width:24px;height:24px;display:inline-block;background-size:contain!important}.grammar-body .row{gap:10px;display:flex}.grammar-body .grammar-article-example-icon{flex:none;margin-top:12px}.grammar-body .grammar-article-example-icon i,.grammar-body .number{place-items:center;display:inline-grid}.grammar-body .grammar-article-example-unnumbered:before{content:"";background:#58c0a9;border-radius:50%;width:10px;height:10px;display:block}.grammar-body .number{color:#fff;background:#58c0a9;border-radius:12px;width:24px;height:24px;font-weight:700}.grammar-body .grammar-article-example-content-p{font-family:var(--font-cjk);margin:0;font-size:1.3em;font-weight:300}.grammar-body ruby{vertical-align:bottom;flex-direction:column-reverse;align-items:center;margin:0 .12em;display:inline-flex}.grammar-body rt{font-family:var(--font);color:#404040;white-space:nowrap;font-size:.6em;line-height:1.5}.grammar-body .notes{background:#efefef;border-radius:10px;margin-bottom:1.5em;padding:12px}.grammar-body table{border-collapse:collapse;margin-bottom:1em}.grammar-body td,.grammar-body th{border:1px solid #ddd;padding:4px 8px}.grammar-body a{color:var(--link)}.du-dict-header{background:#f6f6f8;border-radius:10px;margin-top:20px;padding:16px}.du-dict-hsk{float:right}.du-dict-hanzi{font-family:var(--font-cjk);color:#1a191c;font-size:2em;display:inline-block}.du-dict-hanzi.is-alt{color:#b3b2b9;margin-left:.5em}.du-dict-pinyin{color:#3e80af;margin-top:.5em;font-family:Helvetica,sans-serif;font-size:1.25em}.du-dict-meaning{margin-top:4px;font-size:16px}.du-dict-section{margin-top:20px}.du-dict-toggle{background:0 0;border:0;align-items:center;gap:10px;padding:0;font-size:22px;font-weight:400;display:flex}.du-chevron{border-bottom:2px solid #4d4c53;border-right:2px solid #4d4c53;width:9px;height:9px;transition:transform .2s;transform:rotate(-45deg)}.du-chevron.is-open{transform:translateY(-3px)rotate(45deg)}.du-dict-entry{margin-top:12px}.du-dict-entry-pinyin{color:#3e80af;padding-left:12px;font-family:Helvetica,sans-serif;font-size:15px}.du-dict-character{font-family:var(--font-cjk);font-size:22px}.du-dict-meanings{margin:6px 0 0;padding:0;list-style:none}.du-dict-meanings li{color:#1a191c;align-items:flex-start;gap:10px;margin-bottom:6px;font-size:15px;display:flex}.du-dict-n{background:#eeedf1;border-radius:50%;flex:0 0 24px;place-items:center;height:24px;font-size:13px;display:inline-grid}.du-toast{z-index:50;color:#fff;background:#63bdab;border-radius:6px;padding:10px 18px;font-size:14px;font-weight:400;position:fixed;bottom:96px;left:50%;transform:translate(-50%);box-shadow:0 6px 18px #00000026}.du-word-list{margin:0;padding:0;list-style:none}.du-word-list li{border-bottom:1px solid #eee;grid-template-columns:110px 140px 1fr auto auto;align-items:baseline;gap:12px;padding:10px 4px;display:grid}.du-word-list-hanzi{font-family:var(--font-cjk);border-bottom:2px solid;justify-self:start;font-size:22px}.du-word-list-pinyin{color:#3e80af}.du-word-list-meaning{font-size:14px}.du-word-list-source{font-size:12px}.du-word-list-remove{color:#aaa;background:0 0;border:0;padding:0 6px;font-size:18px}@media (width<=600px){.du-word-list li{grid-template-columns:auto 1fr auto}.du-word-list-meaning{grid-column:1/-1}.du-word-list-source{display:none}}.du-gate{z-index:100;background:linear-gradient(180deg, var(--red), var(--red-dark));place-items:center;display:grid;position:fixed;inset:0}.du-gate-card{text-align:center;background:#fff;border-radius:10px;width:min(360px,90vw);padding:32px 28px;box-shadow:0 20px 60px #00000040}.du-gate-card img{width:44px;height:44px;margin:0 auto 8px}.du-gate-card h1{margin:0 0 4px;font-size:22px;font-weight:400}.du-gate-card p{color:var(--muted);margin:0 0 20px;font-size:14px}.du-gate-card form{flex-direction:column;gap:10px;display:flex}.du-gate-card input{height:44px;font:inherit;text-align:center;letter-spacing:.3em;border:1px solid #ddd;border-radius:6px;outline:none;padding:0 12px;font-size:20px}.du-gate-card input:focus{border-color:var(--link)}.du-gate-card input[aria-invalid=true]{border-color:var(--red);background:#fff2f2}.du-gate-card button{background:var(--red);color:#fff;height:42px;font:inherit;border:0;border-radius:6px;font-size:15px}.du-gate-card button:disabled{opacity:.4;cursor:default}.du-gate-error{color:var(--red);margin-top:10px;font-size:13px}.du-sync-title{margin:10px 0 24px;font-size:26px;font-weight:400}.du-sync-section{border:1px solid var(--border);background:#fff;border-radius:8px;margin-bottom:36px;padding:18px 20px}.du-sync-section h2{margin:0 0 6px;font-size:18px;font-weight:400}.du-sync-section p{color:var(--muted);margin:0 0 12px;font-size:14px}.du-sync-section code{background:#f2f2f2;border-radius:3px;padding:1px 4px;font-family:ui-monospace,SFMono-Regular,Menlo,monospace;font-size:13px}.du-sync input{width:320px;height:36px;font:inherit;border:1px solid #ccc;border-radius:6px;outline:none;padding:0 10px;font-size:14px}.du-sync input:focus{border-color:var(--link)}.du-sync-form{flex-wrap:wrap;align-items:center;gap:10px;display:flex}.du-sync-button{background:var(--red);color:#fff;height:36px;font:inherit;border:0;border-radius:6px;padding:0 18px;font-size:14px}.du-sync-button:disabled{opacity:.5;cursor:default}.du-sync-error{border:1px solid var(--red);color:var(--red);background:#fff2f2;border-radius:4px;margin-top:10px;padding:8px 12px;font-size:14px}.du-sync-report{background:#f6f6f8;border-radius:4px;margin-top:14px;padding:10px 12px;font-size:14px}.du-sync-missing{margin:10px 0 0;padding:0;font-size:13px;list-style:none}.du-sync-missing li{border-bottom:1px solid #e8e8e8;grid-template-columns:50px 100px 90px 1fr auto;gap:10px;padding:4px 0;display:grid}.du-sync-tag{text-align:center;border-radius:3px;padding:1px 6px;font-size:10px;font-weight:600}.du-sync-tag.is-free{color:#116f2b;background:#d8f3df}.du-sync-tag.is-paid{color:#864700;background:#ffe4b8}.du-sync-level{text-transform:capitalize;color:var(--muted);font-size:12px}.du-sync-release,.du-sync-course{color:var(--muted);font-size:12px}.du-sync-errors{margin:8px 0 0;padding:0 0 0 20px;font-size:13px}.du-dropdown-sep{background:var(--border);height:1px;margin:4px 0}