:root{--ink:#132b35;--green:#174c42;--paper:#f6f5ef;--line:#dce1da;--muted:#53665f}body.product{background:var(--paper);color:var(--ink)}.product header{height:80px;max-width:1440px;margin:auto;padding:0 5%;gap:25px}.product .brand{letter-spacing:-1.4px}.product nav{display:flex;align-items:center;gap:28px;font-size:13px}.product nav a{color:var(--ink);text-decoration:none}.product nav a:hover{text-decoration:underline}.product a{color:var(--green)}.product .button,.product button{background:var(--green)}.product main{max-width:1280px;margin:auto;padding:0 5%}.product .hero{padding:76px 0 66px;display:grid;grid-template-columns:1.1fr 1fr;gap:70px;align-items:center}.product .hero h1{font-family:Georgia,'Times New Roman',serif;font-weight:400;font-size:74px;line-height:1.04;letter-spacing:-3.8px;margin:24px 0}.product .hero h1 em{font-weight:400;color:var(--green)}.product .hero .lead{font-size:18px;max-width:465px}.product .eyebrow{color:var(--green);font-weight:650;letter-spacing:1.5px}.product .hero-note{font-size:12px;color:var(--muted);margin-top:18px}.preview-sheet{background:white;border:1px solid var(--line);box-shadow:0 15px 60px #213a3111;border-radius:12px;overflow:hidden;transform:rotate(1deg)}.preview-top{background:#e9eee6;padding:18px 24px;display:flex;justify-content:space-between;font-size:11px;letter-spacing:1px}.preview-body{padding:28px}.preview-body h3{font-family:Georgia,serif;font-size:27px;font-weight:400;line-height:1.2;margin:12px 0}.mini-response{border-left:2px solid #d5dcce;padding:10px 16px;background:#f8f9f5;color:#5b6a60;font-size:13px;line-height:1.7}.preview-feedback{border:1px solid #d7e3d8;border-radius:8px;padding:17px;margin-top:18px;background:#f1f7ef;font-size:13px;line-height:1.7}.preview-feedback strong{display:block;color:#24573e;margin-bottom:6px}.product .section-line{border-top:1px solid var(--line);padding:42px 0 56px}.section-heading{display:flex;justify-content:space-between;align-items:end;gap:35px;margin-bottom:28px}.section-heading h2{font:400 36px/1.2 Georgia,serif;letter-spacing:-1px;margin:10px 0}.section-heading p{max-width:365px;font-size:14px;margin:0}.path-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}.path-card{display:flex;flex-direction:column;align-items:start;border:1px solid var(--line);border-radius:10px;padding:26px;background:#fff;min-height:285px}.path-card.featured{background:#e9eee4}.path-card .index{font-size:11px;color:#63786d}.path-card h3{font:400 25px/1.2 Georgia,serif;margin:25px 0 12px}.path-card p{font-size:14px;line-height:1.7;margin-bottom:24px}.path-card a{margin-top:auto;font-size:13px;font-weight:600}.topic-links{display:grid;grid-template-columns:repeat(4,1fr);gap:10px}.topic-links a{padding:17px 15px;border:1px solid var(--line);background:#fff;border-radius:6px;text-decoration:none;font-size:13px;display:flex;justify-content:space-between}.product footer{max-width:1280px;color:#53665f;padding:30px 5%;font-size:12px}.product .faq{max-width:780px}.product .faq details{padding:17px 0;border-bottom:1px solid var(--line)}.product .faq summary{font-size:15px}.product .split-note{display:grid;grid-template-columns:1fr 1fr;gap:60px}.product .split-note h2{font:400 34px/1.2 Georgia,serif;letter-spacing:-1px}.product .split-note p{font-size:14px}.product .secondary-link{font-size:13px}.product .skip-link{position:absolute;left:12px;top:-70px}.product .skip-link:focus{top:12px;background:white;padding:12px;z-index:10}.product .library-shell{display:grid;grid-template-columns:230px 1fr;gap:45px;padding:45px 0}.product .library-aside{padding:0;border:0}.product .library-aside h1{font:400 31px/1.2 Georgia,serif;letter-spacing:-1px}.product .library-aside p{font-size:13px}.product .library-content{min-width:0}.product .library-content .card{box-shadow:none;border-radius:10px}.product .library-content h2{font-family:Georgia,serif;font-weight:400}.product .library-content label{font-size:13px}.product .concept-option:has(input:checked){border-color:var(--green);background:#eef5eb}.concept-option{border:1px solid var(--line);padding:12px;border-radius:6px;cursor:pointer}.product .filters{display:grid;grid-template-columns:1fr 2fr;gap:20px}.product .card p{color:#465d54}.product .guide-note{padding:15px;border:1px solid var(--line);border-radius:7px;font-size:12px;line-height:1.7;margin-top:25px}.product .topic-page{max-width:900px;padding-top:50px}.product .topic-page h1{font:400 48px/1.1 Georgia,serif;letter-spacing:-2px}.product .topic-page .card{box-shadow:none}.product .topic-page ul{padding-left:22px}.product .topic-page li{display:list-item;font-size:14px;color:var(--muted);padding:5px 0}.product .topic-page li:before{display:none}.product pre{white-space:pre-wrap;overflow-wrap:anywhere;background:#e9eee6;padding:18px;border-radius:7px;font-size:12px}.product .topic-page .equation{font-family:ui-monospace,monospace;font-size:13px;line-height:1.8;background:#f0f3eb;padding:14px;border-radius:6px}.product .question-links{display:grid;gap:10px}.question-links a{display:block;border-bottom:1px solid var(--line);padding:14px 0;font-size:15px;text-decoration:none}
@media(max-width:950px){.product .hero{gap:35px}.product .hero h1{font-size:60px}.product nav{gap:16px}.product .topic-links{grid-template-columns:repeat(2,1fr)}.product .library-shell{grid-template-columns:180px 1fr;gap:26px}.product .preview-body{padding:22px}}
@media(max-width:650px){.product header{height:72px;padding:0 20px}.product nav{gap:18px}.product nav .desktop-only{display:none}.product main{padding:0 20px}.product .hero{grid-template-columns:1fr;padding:40px 0;gap:32px}.product .hero h1{font-size:54px;letter-spacing:-2.7px}.product .hero .lead{font-size:16px}.preview-sheet{transform:none}.product .hero .actions{align-items:start}.path-grid{grid-template-columns:1fr}.path-card{min-height:220px}.section-heading{display:block}.section-heading p{margin-top:16px}.product .section-line{padding:32px 0}.product .split-note{grid-template-columns:1fr;gap:20px}.product .library-shell{grid-template-columns:1fr;gap:20px;padding-top:24px}.product .library-aside{display:block;border:0;padding:0}.product .library-aside h1,.product .library-aside p{display:block}.product .library-aside .guide-note{display:none}.product .filters{grid-template-columns:1fr;gap:0}.product .topic-page{padding-top:30px}.product .topic-page h1{font-size:36px}.product footer{padding:25px 20px}.product .topic-links a{font-size:12px;padding:14px 10px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important}}
.product .micro{color:#5d6d67}.product .library-aside .eyebrow{display:block}.product .path-card:focus-within{outline:2px solid #a9c4b5;outline-offset:3px}.product select{border-color:#bdc9c1}.product .callout{background:#edf3e8;border-color:#638a69}.product input:focus-visible,.product textarea:focus-visible,.product a:focus-visible,.product button:focus-visible,.product select:focus-visible{outline-color:#8db59a}
.product a.button{color:#fff}
/* Product-first landing page: compact hierarchy and live practice. */
.product-first-home{background:#fbfcfa}.product-first-home header{border:1px solid #dce2dc;border-radius:12px;margin:18px auto 0;max-width:1180px;height:66px;padding:0 26px}.product-first-home .brand{font-weight:800}.product-first-home main{max-width:1180px}.product .product-first{display:block;padding:57px 0 25px;text-align:center}.product .product-first h1{font-family:Inter,ui-sans-serif,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:52px;font-weight:760;line-height:1.1;letter-spacing:-2.6px;margin:22px 0}.product .product-first .lead{max-width:650px;margin:0 auto;font-size:18px;line-height:1.6}.product .product-first .actions{justify-content:center;margin-top:24px}.product .product-first .button{border-radius:30px;padding:14px 24px;background:#142e27;box-shadow:0 3px 0 #0b1e1815}.product .product-first .hero-note{font-size:11px;margin:14px 0}.scope-strip{display:flex;justify-content:center;gap:26px;margin:26px auto 0;color:#66756d;font-size:12px}.scope-strip span+span:before{content:'·';margin-right:26px;color:#9ba69e}.live-sample-section{max-width:820px;margin:18px auto 65px}.sample-heading{display:flex;justify-content:space-between;align-items:end;gap:15px;margin-bottom:18px}.product .sample-heading h2{font-family:inherit;font-size:24px;letter-spacing:-.8px;margin:9px 0 0}.sample-tabs{display:flex;gap:7px;margin-bottom:12px}.product .sample-tabs button{background:transparent;color:#53685d;border:1px solid #d6e0d7;padding:8px 15px;border-radius:6px;font-size:12px}.product .sample-tabs button[aria-pressed=true]{background:#e4eee2;color:#234e34;border-color:#a6bea6}.sample-window{background:#fff;border:1px solid #d5ded5;border-radius:12px;box-shadow:0 10px 40px #21372a08;overflow:hidden}.sample-window-top{display:flex;justify-content:space-between;gap:12px;background:#f5f7f3;border-bottom:1px solid #e0e6dd;padding:14px 22px;font-size:10px;letter-spacing:1.2px;color:#6e7d70}.sample-content{padding:25px 30px}.sample-content h3{font-family:inherit;font-weight:650;font-size:22px;line-height:1.3;margin:13px 0}.sample-content p{font-size:14px;line-height:1.7}.sample-content p.micro{font-size:11px}.sample-content label{font-size:12px;margin-top:18px}.sample-input-row{display:flex;gap:10px}.sample-input-row input{min-width:0}.sample-input-row button{white-space:nowrap;font-size:12px}.sample-content select{font-size:13px}.sample-result{border-top:1px solid #dce4d9;padding-top:22px;margin-top:24px;font-size:14px}.sample-result>strong{display:block;font-size:17px;color:#315a3f}.sample-result.review>strong{color:#865b25}.sample-equation{background:#f5f7f1;border-radius:6px;padding:13px 15px;font-family:ui-monospace,monospace;font-size:12px;margin:16px 0}.sample-result a{font-size:13px;font-weight:600}.sample-footnote{font-size:11px;text-align:center;color:#6c7b70;line-height:1.6}.product-first-home .section-heading h2,.product-first-home .split-note h2,.product-first-home .path-card h3{font-family:inherit;font-weight:650}.product-first-home .section-heading h2{font-size:30px}.product-first-home .path-card h3{font-size:22px}.product-first-home .split-note h2{font-size:30px}.product-first-home .path-card{min-height:270px}.product-first-home .faq h2{font-family:inherit;font-size:30px;font-weight:650}.product-first-home .brand span{font-size:12px;color:#6a7d70}
@media(max-width:650px){.product-first-home header{margin:12px 14px 0;padding:0 18px;height:62px}.product .product-first{padding:40px 0 20px}.product .product-first h1{font-size:37px;letter-spacing:-1.7px;line-height:1.12}.product .product-first h1 br{display:none}.product .product-first .lead{font-size:16px;max-width:340px}.product .product-first .lead br{display:none}.scope-strip{gap:8px;flex-wrap:wrap;font-size:10px;margin-top:22px}.scope-strip span+span:before{margin-right:8px}.sample-heading{display:block}.sample-heading>.micro{display:block;margin-top:10px}.sample-content{padding:22px 18px}.sample-input-row{display:block}.sample-input-row button{width:100%;margin-top:10px}.sample-window-top{padding:13px 16px;font-size:9px}.sample-content h3{font-size:21px}.live-sample-section{margin-bottom:35px}.product-first-home .path-card{min-height:230px}}
.sr-only{position:absolute!important;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.practice-card h2{font-family:Inter,ui-sans-serif,-apple-system,sans-serif!important;font-weight:650!important;font-size:29px!important;letter-spacing:-1px!important;line-height:1.25!important;margin:20px 0!important}.practice-question-heading{display:flex;justify-content:space-between;gap:12px;align-items:center}.practice-prompt{font-size:17px!important;line-height:1.75!important;margin:20px 0}.assumptions{background:#f4f7f0;padding:14px 16px;border:1px solid #e0e6d9;border-radius:7px}.assumptions summary{font-size:12px;color:#516a58}.assumptions p{font-size:13px;line-height:1.7}.prompt-actions{display:flex;gap:12px;margin-top:28px;flex-wrap:wrap}.question-navigation{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-top:28px;padding-top:20px;border-top:1px solid #e0e5dc}.question-navigation span{font-size:11px;color:#62766a}.question-navigation button{padding:9px 12px;font-size:12px}.concept-fieldset{border:0;padding:0;margin:25px 0}.concept-fieldset legend{font-size:14px;font-weight:650}.concept-fieldset>p{font-size:14px}.product .concept-option{display:flex;align-items:start;gap:12px;font-size:13px;font-weight:400;line-height:1.6}.concept-option input{width:auto;flex-shrink:0;margin-top:4px;accent-color:#174c42}.practice-card label small{font-weight:400;color:#677b6e}.practice-review-summary{padding:20px;border:1px solid #d5e1d0;border-radius:8px;background:#edf4e8;margin-bottom:20px}.practice-review-summary>strong{font-size:18px;line-height:1.4}.practice-review-summary p{font-size:13px;margin-bottom:0}.practice-review-summary.needs-review{background:#fbf4e8;border-color:#e8d7b8}.worked-bridge{border:1px solid #dde5d7;background:#f7f9f3;padding:16px 18px;border-radius:7px}.worked-bridge p{font:13px/1.8 ui-monospace,monospace;margin:5px 0;overflow-wrap:anywhere}.retry-inputs{background:#eff5e9;border:1px solid #d5e1ca;padding:16px;border-radius:7px;margin:20px 0}.retry-inputs>strong{font-size:13px}.retry-inputs dl{display:grid;grid-template-columns:repeat(2,1fr);gap:12px;font-size:12px}.retry-inputs dl>div{display:flex;gap:10px;align-items:baseline}.retry-inputs dt{color:#5d7263}.retry-inputs dd{margin:0;font-weight:650}.practice-card #attempt textarea{min-height:95px}#exercise{outline:none}
@media(max-width:650px){.practice-card h2{font-size:25px!important}.practice-prompt{font-size:16px!important}.practice-question-heading{align-items:start}.question-navigation{gap:6px}.question-navigation button{padding:9px;font-size:11px}.question-navigation span{font-size:10px}.retry-inputs dl{grid-template-columns:1fr}.prompt-actions button{width:100%}.practice-card .input-grid{grid-template-columns:1fr}}
.product .self-review{padding-left:20px;margin:12px 0}.product .self-review li{display:list-item;color:#53685b;font-size:13px;line-height:1.7;padding:5px 0}.product .self-review li:before{display:none}.practice-card .result{padding:15px 0}.practice-card .result p{font-size:13px}.practice-card .table-wrap{margin:15px 0}.practice-card .table-wrap table{font-size:12px}.practice-card .table-wrap th{font-size:11px}.practice-card .retry-inputs summary{font-size:12px}.practice-card .actions{margin-bottom:8px}
.product button.secondary{background:transparent;color:var(--green);border:1px solid #bacbbd}.product button.secondary:hover{background:#edf4e8}.product .library-aside h1{font-family:Inter,ui-sans-serif,-apple-system,sans-serif;font-weight:650;font-size:29px;letter-spacing:-1px}.product .topic-page h1{font-family:Inter,ui-sans-serif,-apple-system,sans-serif;font-weight:700}.practice-card .result:first-of-type{border-top:0}
.campus-strip{display:flex;justify-content:space-between;align-items:center;gap:35px}.campus-strip h2{font-family:inherit;font-size:30px;font-weight:650}.campus-strip p{max-width:600px;font-size:14px}.campus-strip .actions{flex-shrink:0;flex-direction:column;align-items:start}.institution-grid{display:grid;grid-template-columns:1fr 1fr;gap:22px 60px}.institution-grid h3{font-size:18px}.institution-grid p{font-size:14px}.institution-pilot{display:grid;grid-template-columns:1.2fr 1fr;gap:50px;align-items:start}.institution-pilot h2{font-family:inherit;font-weight:650;font-size:34px}.institution-pilot p{font-size:14px}.institution-pilot .card{margin:0}.institution-page .hero-copy{max-width:800px;margin:auto}.workshop-plan table{white-space:normal}.workshop-plan th,.workshop-plan td{text-align:left;vertical-align:top}.workshop-plan td:first-child{white-space:nowrap}.workshop-plan h2{font-size:27px}.workshop-plan a{font-size:14px}
@media(max-width:650px){.campus-strip{display:block}.campus-strip .actions{align-items:stretch}.campus-strip .actions a{text-align:center}.institution-grid{grid-template-columns:1fr;gap:10px}.institution-pilot{grid-template-columns:1fr;gap:25px}.institution-pilot h2{font-size:29px}.workshop-plan table{min-width:520px}.institution-page .product-first h1 br{display:none}}

.practice-storage{margin:20px 0;padding:16px;border:1px solid var(--line);border-radius:12px;background:#fff}.practice-storage summary{cursor:pointer;font-weight:650}.save-choice{display:flex;align-items:center;gap:10px;margin-top:16px}.save-choice input{width:18px;height:18px;margin:0}

.practice-plan{margin:16px 0;padding:16px;border:1px solid var(--line);border-radius:12px}.practice-plan summary{font-weight:650;cursor:pointer}.product .plan-link{background:transparent;border:0;color:var(--green);padding:0;text-align:left;text-decoration:underline;border-radius:0}.practice-plan li{margin:16px 0}

body.product.seo-guide{background:#fff}.seo-guide .topic-page{max-width:820px}.seo-guide .topic-page>nav[aria-label="Breadcrumb"]{display:block;font-size:11px;margin-bottom:24px;color:#7a8272}.seo-guide .topic-page>nav[aria-label="On this page"]{display:block;background:#fafbf8;padding:20px;border:1px solid #e8ece2;border-radius:8px;margin:28px 0}.seo-guide .topic-page h1{font-size:38px;line-height:1.16;font-weight:550;letter-spacing:-1px}.seo-guide .topic-page h2{font-size:24px;line-height:1.3;font-weight:550;letter-spacing:-.5px}.seo-guide .callout h2{font-size:22px;margin-top:0}.seo-guide .topic-page section{scroll-margin-top:25px}.seo-guide .topic-page p{font-size:15px;line-height:1.85}.seo-guide .topic-page li{font-size:13px;line-height:1.8}@media(max-width:650px){.seo-guide .topic-page h1{font-size:29px}.seo-guide .topic-page h2{font-size:22px}.seo-guide .topic-page p{font-size:14px}.seo-guide .callout{padding:20px}}
/* A calmer question surface and lightweight study tools. */
.product .study-toolbar{display:flex;justify-content:space-between;align-items:center;gap:12px;margin:24px 0 8px}.study-view-switch{display:flex;gap:3px;border:1px solid #e1e5dc;background:#f4f6f0;padding:3px;border-radius:8px}.product .study-view-switch button{background:transparent;border:0;color:#7b8470;font-size:12px;padding:8px 17px;border-radius:5px;box-shadow:none}.product .study-view-switch button[aria-pressed=true]{background:#fff;color:#2b3a24;box-shadow:0 1px 3px #263b2010}.product .highlight-action{background:#fff7d9;color:#77602d;border:1px solid #ebdfb8;font-size:11px;padding:9px 13px;border-radius:6px;box-shadow:none}.product .practice-card{border:1px solid #e4e8df;border-radius:13px;box-shadow:none;padding:30px}.product .practice-card h2{font-family:inherit;font-weight:550;font-size:25px;line-height:1.25;letter-spacing:-.6px;margin:20px 0}.product .practice-card .practice-prompt,.product .flashcard-question{font-size:18px;line-height:1.8;color:#35402e;max-width:70ch;margin:25px 0}.product .practice-question-heading{padding-bottom:16px;border-bottom:1px solid #edf0e8}.product .practice-card .assumptions{border:0;background:#f7f8f4;border-radius:7px;padding:12px 15px;margin:22px 0}.product .practice-card .assumptions summary{font-size:11px;color:#7b846f}.product .practice-card .prompt-actions{margin-top:28px;padding-top:22px;border-top:1px solid #edf0e8}.product .practice-card button{font-size:12px;border-radius:6px}.product .practice-card .question-navigation{border-top:1px solid #edf0e8;padding-top:20px;margin-top:30px}.product .saved-highlights{margin:16px 0 24px;border:0;padding:0}.saved-highlights summary{font-size:11px;color:#7a866d;cursor:pointer}.saved-highlights summary span{margin-left:5px;border-radius:10px;padding:2px 6px;background:#eff2e9;font-size:10px}.highlight-entry{display:flex;align-items:center;gap:12px;margin:12px 0;border-left:3px solid #e3ca75;padding:10px 14px;background:#fffcf0}.highlight-entry blockquote{font-size:12px;line-height:1.6;margin:0;flex:1;overflow-wrap:anywhere}.product .highlight-entry button{font-size:10px;padding:5px 8px}.practice-card mark{background:#fae9a2;color:inherit;padding:1px 0;box-decoration-break:clone}.product .flashcard{min-height:390px}.flashcard-controls{margin-top:32px;padding-top:22px;border-top:1px solid #edf0e8}.self-rating{display:flex;gap:10px;margin:18px 0}.product .flashcard-answer p{font-size:15px;line-height:1.8}.product .study-equation{background:#f5f7f0;border:1px solid #e8edde;border-radius:7px;padding:12px 16px;font:13px/1.7 ui-monospace,SFMono-Regular,monospace;overflow-wrap:anywhere}.product .library-aside h1{font-size:27px;font-weight:550;line-height:1.2;letter-spacing:-.6px}.product .practice-card .eyebrow{font-size:10px;letter-spacing:1px}.product .practice-card .micro{font-size:11px;line-height:1.65}@media(max-width:650px){.product .practice-card{padding:22px}.product .practice-card h2{font-size:22px}.product .practice-card .practice-prompt,.product .flashcard-question{font-size:16px;line-height:1.8}.product .study-toolbar{gap:7px}.product .study-view-switch button{padding:8px 11px;font-size:11px}.product .highlight-action{font-size:10px;padding:9px}.product .flashcard{min-height:350px}}