.reader-shell{--reader-ink:#17353e;--reader-muted:#627a80;--reader-teal:#225e68;--reader-line:#dce6e6;min-height:100vh;background:#f0f4f4;color:#21333d;font-family:"Microsoft YaHei","PingFang SC",system-ui,sans-serif;font-size:16px;line-height:1.85;text-align:left}
.reader-shell *{box-sizing:border-box}.reader-shell button,.reader-shell summary{font:inherit;cursor:pointer}.reader-shell a{color:#216978;text-underline-offset:4px}.reader-shell button:disabled{cursor:not-allowed}
.reader-shell :is(a,button,summary,input):focus-visible{outline:3px solid #c49743;outline-offset:3px}.reader-sidebar{position:fixed;inset:0 auto 0 0;width:260px;padding:30px 22px;background:#15333b;color:#eaf4f2;overflow-y:auto;z-index:30}
.reader-sidebar .reader-brand{color:#bdd9d4;font-size:12px;letter-spacing:2px;text-decoration:none}.reader-course{font-size:30px;font-weight:750;line-height:1.4;margin:16px 0 28px}.reader-course>span{display:block;font-size:13px;font-weight:400;color:#b7d3d0;margin-top:7px}.reader-sidebar-label{color:#9fc2bf;font-size:12px;letter-spacing:2px;margin-bottom:12px}
.reader-sidebar .reader-nav-item{display:flex;align-items:center;gap:13px;padding:12px;margin:4px 0;border-radius:9px;color:#d3e4e2;text-decoration:none;font-size:14px;line-height:1.65;overflow-wrap:anywhere}.reader-nav-item:hover{background:#234851}.reader-sidebar .reader-nav-item[aria-current=page]{background:#e4eeeb;color:#15333b}.reader-number{font-size:12px;opacity:.7;min-width:23px}.reader-nav-item small{display:block;font-size:11px;opacity:.7}.reader-side-foot{margin-top:28px;padding-top:18px;border-top:1px solid #365158}.reader-side-foot a{color:#bdd9d4;font-size:12px}
.reader-main{margin-left:260px;padding:28px 42px 36px;max-width:1280px;min-width:0}.reader-toolbar{display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin-bottom:22px}.reader-toolbar a,.reader-toolbar button{display:inline-flex;align-items:center;gap:7px;border:1px solid #cedddd;border-radius:7px;background:#f9fbfb;padding:7px 12px;text-decoration:none;font-size:13px;color:#345d65}.reader-toolbar button:disabled{color:#74858a;background:transparent;border-style:dashed}.reader-card{background:white;border:1px solid var(--reader-line);border-radius:18px;padding:36px 42px;box-shadow:0 8px 28px #20333d06;min-width:0}.reader-heading{padding-bottom:24px;border-bottom:1px solid #e4ebeb;margin-bottom:28px}.reader-eyebrow{font-size:12px;color:#627a80;letter-spacing:1px;margin:0 0 10px}.reader-heading h1{font-size:27px;line-height:1.5;margin:0 0 17px;color:var(--reader-ink);letter-spacing:-.4px;overflow-wrap:anywhere}.reader-topics{display:flex;flex-wrap:wrap;gap:7px}.reader-topics>span{font-size:12px;line-height:1.7;color:#3d696d;background:#edf5f2;padding:4px 9px;border-radius:5px}.reader-resource-actions{display:flex;flex-wrap:wrap;gap:12px;margin-top:18px;font-size:13px}.reader-resource-actions button{background:white;border:1px solid #cadbdc;border-radius:6px;padding:6px 10px;display:inline-flex;align-items:center;gap:6px;color:#225e68}
.reader-disclosure{border:1px solid var(--reader-line,#dce6e6);border-radius:9px;margin:12px 0;overflow:hidden}.reader-disclosure-toggle{display:flex;align-items:center;justify-content:space-between;gap:14px;width:100%;border:0;background:#f7faf9;color:#275e67;padding:15px 18px;text-align:left;font-weight:600!important;line-height:1.7!important}.reader-disclosure-toggle>svg{flex-shrink:0;transition:transform .2s}.reader-disclosure-toggle[aria-expanded=true]>svg{transform:rotate(180deg)}.reader-disclosure-body{padding:8px 20px 20px;min-width:0}.reader-reveal-block{min-width:0}.reader-disclosure-body[data-animate=true]>.reader-reveal-block{animation:reader-reveal .6s both;animation-delay:var(--reveal-delay,0ms)}@keyframes reader-reveal{from{opacity:0;transform:translateY(4px)}to{opacity:1;transform:translateY(0)}}
.reader-shell h2,.reader-shell h3,.reader-shell h4{color:var(--reader-ink);line-height:1.55}.reader-shell h2{font-size:21px}.reader-shell h3{font-size:18px}.reader-shell p{overflow-wrap:anywhere}.reader-shell img{max-width:100%;height:auto}.reader-shell figure{margin:22px 0}.reader-shell .math-block,.reader-shell .equation,.reader-shell .katex-display{max-width:100%;overflow-x:auto;overflow-y:hidden}.reader-shell .content-card{box-shadow:none;border-color:#e0e9e8;border-radius:10px;margin:16px 0}.reader-shell .question-image-card{border:0;padding:0;margin:0 0 28px}.reader-shell .question-reference-image{width:auto;max-width:100%;max-height:700px;object-fit:contain}.reader-shell .question-image-frame{background:#f8faf9}.reader-shell .packet-section{border:0;background:transparent;margin:24px 0}.reader-shell .reader-step-group{margin:26px 0}.reader-shell .reader-step-group>h3{font-size:15px;color:#577078}.reader-shell .solution-step{display:block;margin:0;padding:0;border:0}.reader-shell .step-block{margin:12px 0}.reader-shell .step-block>small{display:block;color:#5b7c7b;font-size:12px;margin-bottom:5px}.reader-shell .step-why{background:#eef7f2;border-radius:7px;padding:12px 16px}.reader-shell .teaching-question-nav{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-top:28px;font-size:13px}.reader-shell .teaching-question-nav a,.reader-shell .teaching-question-nav button{display:inline-flex;gap:4px;align-items:center;padding:6px 10px;border:1px solid #cadbdc;border-radius:6px;background:white;color:#225461;text-decoration:none}.reader-shell .teaching-question-nav button:disabled{opacity:.4}.reader-footer{text-align:center;color:#74898b;font-size:12px;margin:24px 0}.reader-mobile-bar,.reader-close,.reader-backdrop{display:none}.reader-skip{position:fixed;top:-100px;left:12px;z-index:100;background:white;padding:8px 16px}.reader-skip:focus{top:8px}
.reader-shell .cn-originals{margin:0 0 24px}.reader-shell .cn-originals button{border:1px solid #dce6e6;border-radius:9px;background:#f8faf9;max-width:100%;padding:10px}.reader-shell .cn-originals span{display:block;font-size:12px;color:#627a80}.reader-shell .cn-pagination{margin-top:28px}.reader-shell .reader-source-note{font-size:12px;color:#698087}.reader-shell .econ-options{grid-template-columns:1fr}.reader-shell .econ-analysis{width:100%;table-layout:fixed}.reader-shell .econ-analysis td{overflow-wrap:anywhere}.reader-shell .econ-formula{max-width:100%;overflow-x:auto}.reader-shell .reader-original-text{padding:16px 22px;background:#f5f8f8;border-left:3px solid #3d777b;margin-bottom:24px}
.reader-directory-title{min-width:0}.reader-directory-title strong{display:block;font-size:16px;line-height:1.6}.reader-directory-topics{display:flex;gap:6px;flex-wrap:wrap;margin-top:8px}.reader-directory-topics span{font-size:12px;color:#456b71;background:#edf5f2;padding:3px 8px;border-radius:4px}.question-directory-row:has(.reader-directory-title){display:grid;grid-template-columns:58px minmax(0,1fr) auto;gap:18px}
@media(min-width:1540px){.reader-main{margin-left:280px}.reader-sidebar{width:280px}}
@media(max-width:1100px){.reader-sidebar{width:220px;padding:25px 16px}.reader-main{margin-left:220px;padding:22px}.reader-card{padding:28px}.reader-heading h1{font-size:24px}}
@media(max-width:760px){.reader-sidebar{transform:translateX(-100%);visibility:hidden;width:min(310px,85vw);transition:transform .2s,visibility .2s}.reader-sidebar.is-open{transform:none;visibility:visible}.reader-main{margin:0;padding:15px 12px 28px}.reader-mobile-bar{display:flex;justify-content:space-between;align-items:center;background:#15333b;color:#d3e4e2;padding:12px 16px;gap:8px;font-size:12px}.reader-mobile-bar button{display:flex;gap:7px;align-items:center;color:#fff;background:transparent;border:1px solid #52716f;border-radius:6px;padding:6px 9px}.reader-close{display:flex;align-items:center;gap:8px;color:#eaf4f2;background:transparent;border:0;margin:0 0 20px auto}.reader-backdrop{display:block;position:fixed;inset:0;z-index:29;background:#102d3655;border:0}.reader-toolbar{gap:7px;margin-bottom:15px}.reader-toolbar a,.reader-toolbar button{font-size:12px;padding:6px 8px}.reader-card{padding:23px 17px;border-radius:12px}.reader-heading h1{font-size:21px;line-height:1.6}.reader-heading{padding-bottom:19px;margin-bottom:22px}.reader-disclosure-toggle{font-size:14px!important;padding:13px}.reader-disclosure-body{padding:5px 13px 16px}.reader-shell .content-card{padding:16px}.reader-shell .question-image-card{padding:0}.reader-shell .step-why{padding:10px}.question-directory-row:has(.reader-directory-title){grid-template-columns:40px minmax(0,1fr);gap:10px}.question-directory-row:has(.reader-directory-title)>a{grid-column:2;justify-self:start}.reader-shell .reader-resource-actions{gap:8px}.reader-shell .cn-pagination{font-size:13px}}
@media(prefers-reduced-motion:reduce){.reader-shell *, .reader-disclosure-body[data-animate=true]>.reader-reveal-block{animation:none!important;transition:none!important}}
@media print{.reader-sidebar,.reader-toolbar,.reader-mobile-bar,.reader-footer{display:none!important}.reader-main{margin:0;padding:0}.reader-card{padding:0;border:0;box-shadow:none}.reader-disclosure-body[data-animate=true]>.reader-reveal-block{animation:none}}
.reader-shell .reader-chemistry{min-height:0;background:transparent;font:inherit}

/* One continuous reading surface; only hints and score conditions remain nested. */
.reader-continuous-step{padding:22px 0;border-bottom:1px solid #e5ece9;min-width:0}
.reader-continuous-step:last-child{border-bottom:0}.reader-continuous-step h4{font-size:1.1rem;color:#164d49;margin:0 0 16px}
.reader-strategy{margin:24px 0;padding:20px 24px;background:#f2f7f5;border-left:3px solid #62968a;border-radius:8px;line-height:1.85}
.reader-full-solution>.reader-disclosure-body{padding:8px 28px 28px}.reader-full-solution .reader-step-group{border:0;box-shadow:none}
.reader-disclosure-body[data-animate="true"] .reader-reveal-block,.reader-disclosure-body[data-animate="true"] .reader-continuous-step> *{animation-duration:.4s}
.reader-full-solution .reader-reveal-block:has(.reader-continuous-step){animation:none}
.reader-disclosure-body[data-animate="true"] .reader-continuous-step>*{animation:reader-reveal .4s ease both;animation-delay:var(--reveal-delay,0ms)}
.reader-language{display:flex;gap:4px;margin:14px 0 22px}.reader-language button{border:1px solid #9dbbb3;border-radius:6px;padding:7px 12px;background:transparent;color:inherit;cursor:pointer;font:inherit;font-size:.85rem}
.reader-language button[aria-pressed="true"]{background:#d7eee5;color:#164d49;border-color:#d7eee5}.reader-sidebar .reader-language{color:#e3f1ea}
.reader-nav-item>span:last-child{overflow-wrap:anywhere}.reader-directory-topics span,.reader-topics span{overflow-wrap:anywhere}
@media(max-width:760px){.reader-full-solution>.reader-disclosure-body{padding:6px 14px 18px}.reader-strategy{padding:16px}}
@media(prefers-reduced-motion:reduce){.reader-disclosure-body[data-animate="true"] .reader-continuous-step>*{animation:none}}