:root{--ink:#102c45;--muted:#53616b;--paper:#f7f5ef;--line:#d9dedc;--orange:#e96520;--blue:#163b58;--sans:Arial,Helvetica,sans-serif;--serif:Georgia,'Times New Roman',serif}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:100px}body{margin:0;font:16px/1.65 var(--sans);color:var(--ink);background:#fff}h1,h2,h3,p,figure{margin:0}h1,h2{font-family:var(--serif);font-weight:400;letter-spacing:-.035em;line-height:1.14}h2{font-size:clamp(32px,3.3vw,46px)}h3{line-height:1.35}a{color:inherit;text-decoration:none}button,input{font:inherit}button,a,input{touch-action:manipulation}button{cursor:pointer}img{display:block;max-width:100%;height:auto}button:disabled{cursor:default;opacity:.6}[hidden]{display:none!important}a:focus-visible,button:focus-visible,input:focus-visible,summary:focus-visible,[tabindex]:focus-visible{outline:3px solid #2d77bc;outline-offset:5px}p+p{margin-top:16px}.wrap{max-width:1160px;width:calc(100% - 80px);margin-inline:auto}.section-space{padding-block:88px}.eyebrow{font-size:11px;font-weight:700;letter-spacing:.13em;line-height:1.6;color:#576b77;margin-bottom:18px}.text-link{display:inline-flex;align-items:center;gap:16px;font-weight:600;border-bottom:1px solid #9fadb3;padding-bottom:4px}.text-link:hover{color:#c4480a;border-color:currentColor}.button{display:inline-flex;justify-content:space-between;align-items:center;gap:30px;min-height:54px;padding:14px 24px;border:1px solid transparent;border-radius:4px;font-size:15px;font-weight:700;line-height:1.4;transition:background .15s,color .15s}.primary{background:var(--ink);color:#fff}.primary:hover{background:#215273}.secondary{background:#fff;border-color:#aab9c2;color:var(--ink)}.secondary:hover{background:#f3f6f7}.skip-link{position:absolute;z-index:20;top:8px;left:10px;padding:10px;background:white;transform:translateY(-150%)}.skip-link:focus{transform:none}.site-header{position:sticky;top:0;z-index:10;background:#fff;border-bottom:1px solid #e5e8e6}.nav-row{display:flex;justify-content:space-between;align-items:center;min-height:84px;gap:28px}.brand img{width:178px;height:auto}.nav-row nav{display:flex;align-items:center;gap:30px;font-size:13px}.nav-row nav a:hover{text-decoration:underline;text-underline-offset:5px}[data-cart-count]{display:inline-flex;align-items:center;justify-content:center;min-width:22px;height:22px;border-radius:50%;background:#eef1ef;margin-left:5px;font-size:11px}.menu-toggle{display:none}.mini-cart,.whatsapp-float,.cart-toast{display:none!important}
.product-hero{display:grid;grid-template-columns:minmax(0,1.25fr) minmax(0,.75fr);gap:90px;align-items:center;padding-block:72px 80px}.hero-copy h1{font-size:clamp(42px,4.3vw,60px);max-width:650px;margin-bottom:26px}.hero-copy>p:not(.eyebrow):not(.payment-note){font-size:17px;color:var(--muted);max-width:550px;line-height:1.7}.hero-copy .hero-intro{color:var(--ink)!important}.hero-offer{display:flex;gap:24px;align-items:center;margin-block:30px 24px}.hero-offer>strong{font-size:31px;letter-spacing:-.035em;line-height:1.2}.hero-offer>span{font-size:12px;line-height:1.6;border-left:1px solid var(--line);padding-left:24px;color:var(--muted)}.actions{display:flex;gap:26px;align-items:center;flex-wrap:wrap}.actions .button{min-width:202px}.actions .text-link{font-size:14px}.payment-note{font-size:12px;color:var(--muted);margin-top:14px;line-height:1.65}.teacher-byline{display:flex;gap:12px;align-items:center;margin-top:30px;font-size:13px}.teacher-byline img{width:46px;height:46px;object-fit:cover;object-position:center 25%;border-radius:50%}.teacher-byline a{font-weight:700}.teacher-byline small{display:block;font-size:11px;color:var(--muted);margin-top:3px}.hero-book{background:var(--paper);padding:40px 34px 25px;border-radius:6px}.book-frame{border-left:5px solid #18364a;box-shadow:10px 15px 25px #102c4522;transform:rotate(2deg);max-width:310px;margin-inline:auto}.hero-book figcaption{text-align:center;font-size:12px;line-height:1.7;margin-top:28px}.hero-book figcaption span{font-size:11px;color:var(--muted)}
.lesson-section{background:var(--paper);padding-block:76px}.section-intro{display:flex;justify-content:space-between;align-items:end;gap:45px;margin-bottom:36px}.section-intro>p{max-width:335px;color:var(--muted);font-size:16px}.lesson-workspace{display:grid;grid-template-columns:1.08fr 1fr;border:1px solid #cbd4d8;border-radius:8px;overflow:hidden;background:#fff}.question-pane,.explanation-pane{padding:36px}.explanation-pane{background:#eef3f5;border-left:1px solid #cbd4d8;display:flex;align-items:center}.lesson-topline{display:flex;justify-content:space-between;gap:20px;font-size:11px;letter-spacing:.025em;color:var(--muted);margin-bottom:26px}.lesson-topline span:first-child{font-weight:700;color:var(--ink)}fieldset{border:0;padding:0;margin:0;min-width:0}legend{display:block;width:100%;padding:0;font-size:25px;font-weight:700;line-height:1.35;letter-spacing:-.02em}.question-source{font-size:10px;color:#687781;margin-top:14px;line-height:1.6}.answer-options{display:grid;gap:10px;margin-top:25px}.answer-options label{display:flex;align-items:center;gap:13px;position:relative;padding:12px 15px;border:1px solid #d3dce0;border-radius:4px;cursor:pointer;min-height:54px;font-size:15px;line-height:1.45;background:#fff}.answer-options label:hover{background:#f6f8f9;border-color:#a7bac7}.answer-options input{width:18px;height:18px;margin:0;flex-shrink:0;accent-color:var(--ink)}.option-letter{font-size:12px;font-weight:700;color:#637783}.answer-options label:has(input:checked){border-color:var(--blue);background:#edf3f7;box-shadow:inset 3px 0 var(--blue)}.answer-options label.is-correct{border-color:#467b58;background:#eef6ef;box-shadow:inset 3px 0 #467b58}.answer-options label.is-wrong{border-color:#bf754b;background:#fff6ee;box-shadow:inset 3px 0 #bf754b}.quiz-actions{display:flex;align-items:center;justify-content:space-between;gap:20px;margin-top:24px}.quiz-actions .button{font-size:14px;min-height:50px}.text-button{border:0;background:transparent;text-decoration:underline;text-underline-offset:4px;padding:6px;color:var(--muted);font-size:12px}.lesson-placeholder h3{font:32px/1.25 var(--serif);letter-spacing:-.025em;margin-bottom:20px}.lesson-placeholder>p:not(.eyebrow){color:var(--muted);max-width:340px;font-size:15px}.lesson-note{display:flex;gap:18px;border-top:1px solid #d1dce1;margin-top:36px;padding-top:22px;color:#5c707f}.lesson-note>span{font-size:30px;line-height:1}.lesson-note p{font-size:13px;max-width:290px}.lesson-result{width:100%}.answer-feedback{font-size:14px;font-weight:700;color:#24523b;margin-bottom:25px}.answer-feedback[data-correct="false"]{color:#85461f}.lesson-result h3{font:32px/1.2 var(--serif);letter-spacing:-.025em;margin-bottom:10px}.roy-word{font-family:var(--sans);font-weight:800;letter-spacing:.05em}.lesson-result [data-cue]>p{font-size:14px;color:var(--muted)}.roy-cue{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:8px;margin:22px 0}.roy-cue>div{padding:18px 6px 14px;background:#fff;border-radius:4px;text-align:center;border-top:4px solid currentColor}.roy-cue b{display:block;font-size:55px;line-height:1.1}.roy-cue strong{display:block;font-size:12px;margin-top:7px}.roy-cue small{display:block;color:#53616b;font-size:10px;margin-top:4px}.cue-red{color:#b92434}.cue-orange{color:#b7500e}.cue-yellow{color:#916c05}.chemistry-note{padding:13px 15px;background:#fffdf4;border-left:3px solid #d4b23c;line-height:1.65}.lesson-result [data-explanation]{font-size:14px;line-height:1.7;color:var(--muted);margin:18px 0}.lesson-result .button{font-size:13px;min-height:46px;padding:12px 17px}.lesson-result .text-link{font-size:13px}.sample-caption{font-size:12px;color:var(--muted);margin-top:18px}.sample-pages{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:30px}.sample-page .page-image{background:#f2f1ed;border:1px solid #e1e3df;padding:24px;overflow:hidden;height:280px;margin-bottom:22px;transition:background .15s}.page-image img{width:100%;height:100%;object-fit:contain;filter:drop-shadow(2px 4px 4px #102c451a)}.sample-page:hover .page-image{background:#e8edf0}.page-number{display:block;font-size:10px;font-weight:700;letter-spacing:.1em;color:#6a7881;margin-bottom:9px}.sample-page h3{font-size:18px;font-weight:600;margin-bottom:9px;letter-spacing:-.02em}.sample-page p{color:var(--muted);font-size:14px;line-height:1.7;max-width:300px}.page-open{display:inline-flex;gap:20px;font-size:12px;font-weight:700;margin-top:17px;border-bottom:1px solid #acbac1;padding-bottom:3px}.anchor-target{scroll-margin-top:100px}
.package-section{background:var(--paper);border-block:1px solid #e2e3dc}.package-grid{display:grid;grid-template-columns:minmax(0,1.25fr) minmax(0,.75fr);gap:80px;align-items:start}.package-copy h2{font-size:clamp(32px,3vw,42px)}.package-items{margin:32px 0}.package-items>div{display:grid;grid-template-columns:140px 1fr;gap:22px;border-top:1px solid #d9dbd5;padding:22px 0}.package-items dt{font-weight:700;font-size:14px}.package-items dd{margin:0;font-size:14px;color:var(--muted);line-height:1.8}.topics-list{border-block:1px solid #d9dbd5;padding:15px 0;font-size:13px}.topics-list summary{display:flex;justify-content:space-between;gap:15px;font-weight:700;cursor:pointer;list-style:none}.topics-list ul{display:grid;grid-template-columns:1fr 1fr;gap:12px 25px;padding-left:18px;margin:22px 0 8px;color:var(--muted)}.purchase-panel{border:1px solid #bccbd3;border-top:4px solid var(--ink);background:#fff;padding:32px;border-radius:4px}.purchase-panel .eyebrow{margin-bottom:8px}.purchase-panel h3{font:29px var(--serif);margin-bottom:25px}.purchase-price{font-size:45px;font-weight:700;letter-spacing:-.045em;line-height:1.1}.purchase-caption{font-size:12px;color:var(--muted);margin:12px 0 25px}.purchase-panel .button{width:100%;font-size:14px}.purchase-panel .payment-note{text-align:center;font-size:11px}.purchase-panel hr{border:0;border-top:1px solid var(--line);margin:27px 0}.purchase-panel>p:not(.eyebrow):not(.purchase-price):not(.purchase-caption):not(.payment-note){font-size:14px;line-height:1.75}.purchase-panel .scope-note{color:var(--muted);font-size:12px!important}.purchase-panel .text-link{margin-top:22px;font-size:12px;gap:10px}.teacher-section{display:grid;grid-template-columns:300px minmax(0,1fr);gap:80px;align-items:start}.teacher-section figure{margin-top:4px}.teacher-section figure img{width:100%;border-radius:4px}.teacher-section figcaption{margin-top:12px;color:var(--muted);font-size:12px}.teacher-section h2{margin-bottom:24px}.teacher-section>div>p:not(.eyebrow):not(.teacher-signature){color:var(--muted);font-size:17px;line-height:1.85}.teacher-signature{font:italic 28px var(--serif);margin-top:25px;color:var(--ink)}.class-note{margin-top:35px;border-top:1px solid var(--line);padding-top:25px;scroll-margin-top:110px}.class-note h3{font-size:18px;margin-bottom:12px}.class-note p{font-size:14px;color:var(--muted)}.class-note .text-link{font-size:13px;margin-top:18px}.faq-section{background:var(--paper);border-block:1px solid #e2e3dc}.faq-grid{display:grid;grid-template-columns:.8fr 1.2fr;gap:70px}.faq-list details{border-bottom:1px solid #d7dbd8;padding:18px 0}.faq-list details:first-child{padding-top:0}.faq-list summary{display:flex;align-items:center;justify-content:space-between;gap:20px;font-size:16px;font-weight:600;list-style:none;cursor:pointer}.faq-list details[open] summary>span,.topics-list[open] summary>span{transform:rotate(45deg)}.faq-list p{font-size:14px;line-height:1.85;color:var(--muted);margin-top:18px;max-width:540px}.faq-list p a{text-decoration:underline;text-underline-offset:3px}.closing-section{padding-block:65px;display:flex;justify-content:space-between;align-items:center;gap:45px}.closing-section h2{font-size:38px}.closing-section p:not(.eyebrow){font-size:14px;color:var(--muted);margin-top:20px}.closing-section .button{min-width:220px}footer{background:var(--ink);color:#e9f0f4;padding-block:34px;font-size:12px}.footer-row{display:flex;align-items:center;justify-content:space-between;gap:35px;flex-wrap:wrap}.footer-brand{font-size:19px;font-weight:700;line-height:1.5}.footer-brand span{display:block;font-size:11px;font-weight:400;color:#b8c9d4}.footer-row nav{display:flex;gap:20px}.footer-row a:hover{text-decoration:underline;text-underline-offset:4px}
.sample-viewer{width:min(1000px,95vw);height:94dvh;max-height:94dvh;border:0;padding:0;border-radius:6px;color:var(--ink);overflow:hidden;box-shadow:0 25px 70px #0005}.sample-viewer::backdrop{background:#102c45bb}.viewer-toolbar{display:flex;justify-content:space-between;align-items:center;gap:20px;padding:14px 24px;border-bottom:1px solid var(--line);height:68px}.viewer-toolbar h2{font:18px var(--sans);font-weight:700;letter-spacing:0}.viewer-toolbar button{background:#edf1f3;border:1px solid #b9c8d1;border-radius:4px;padding:8px 15px;font-size:13px;color:var(--ink)}.viewer-scroll{height:calc(100% - 68px);overflow:auto;background:#eceeea;padding:20px;overscroll-behavior:contain}.viewer-scroll img{width:100%;max-width:900px;margin:auto;box-shadow:0 2px 8px #0001}body.viewer-open{overflow:hidden}
@media(max-width:1050px){.product-hero{gap:50px}.hero-copy h1{font-size:49px}.hero-book{padding:28px 22px}.question-pane,.explanation-pane{padding:28px}.package-grid{gap:45px}.teacher-section{gap:55px;grid-template-columns:260px minmax(0,1fr)}.package-items>div{grid-template-columns:110px 1fr;gap:17px}.nav-row nav{gap:22px}}
@media(max-width:800px){.wrap{width:calc(100% - 40px)}.nav-row{min-height:70px}.brand img{width:156px}.menu-toggle{display:block;border:1px solid #bdc9cd;background:#fff;padding:7px 12px;border-radius:4px;font-size:13px;color:var(--ink)}.nav-row nav{position:absolute;top:100%;inset-inline:0;background:#fff;border-bottom:1px solid var(--line);display:none;flex-direction:column;align-items:stretch;padding:15px 20px;gap:0}.nav-row nav.is-open{display:flex}.nav-row nav a{padding:12px}.product-hero{grid-template-columns:1.15fr .85fr;gap:30px;padding-block:45px}.hero-copy h1{font-size:38px}.hero-copy>p:not(.eyebrow):not(.payment-note){font-size:15px}.hero-book{padding:24px 16px}.hero-offer{gap:15px}.hero-offer>strong{font-size:28px}.hero-offer>span{padding-left:15px}.actions{gap:18px}.section-space{padding-block:60px}.lesson-section{padding-block:55px}.section-intro{align-items:start;gap:25px}.section-intro>p{font-size:14px;max-width:280px}.lesson-workspace{grid-template-columns:1fr}.explanation-pane{border-left:0;border-top:1px solid #cbd4d8}.lesson-placeholder{width:100%;display:grid;grid-template-columns:1fr 1fr;column-gap:35px}.lesson-placeholder .eyebrow{grid-column:1/-1}.lesson-placeholder h3{font-size:27px}.lesson-note{margin-top:0;padding-top:18px;grid-column:1/-1}.lesson-placeholder>p:not(.eyebrow){font-size:14px}.roy-cue{max-width:400px}.sample-pages{gap:20px}.sample-page .page-image{height:220px;padding:15px}.sample-page h3{font-size:16px}.sample-page p{font-size:13px}.package-grid{gap:30px;grid-template-columns:1.1fr .9fr}.package-items>div{grid-template-columns:1fr;gap:8px}.purchase-panel{padding:24px}.purchase-price{font-size:37px}.teacher-section{grid-template-columns:200px minmax(0,1fr);gap:35px}.teacher-section>div>p:not(.eyebrow):not(.teacher-signature){font-size:15px}.faq-grid{grid-template-columns:1fr;gap:32px}.closing-section h2{font-size:32px}.footer-row{gap:25px}.footer-row nav{flex-wrap:wrap}}
@media(max-width:560px){html{scroll-padding-top:88px}.product-hero{grid-template-columns:1fr;gap:36px;padding-block:36px 42px}.hero-copy h1{font-size:41px;max-width:460px}.hero-copy .eyebrow{font-size:10px}.hero-offer{margin-block:24px 20px}.hero-offer>strong{font-size:30px}.hero-book{max-width:310px;margin:auto;padding:24px 30px 18px}.hero-book .book-frame{max-width:220px}.hero-book figcaption{margin-top:20px}.hero-copy>p:not(.eyebrow):not(.payment-note){font-size:16px}.teacher-byline{margin-top:24px}.section-intro{display:block;margin-bottom:27px}.section-intro>p{margin-top:20px;max-width:none;font-size:15px}.section-intro h2{font-size:35px}.question-pane,.explanation-pane{padding:24px 20px}.lesson-topline{font-size:10px;gap:10px;margin-bottom:23px}legend{font-size:23px}.answer-options label{font-size:14px;padding:13px 11px;gap:10px}.quiz-actions{gap:12px;flex-wrap:wrap}.quiz-actions .button{width:100%}.quiz-actions .text-button{padding-left:0}.lesson-placeholder{display:block}.lesson-placeholder h3{font-size:29px}.lesson-note{margin-top:24px}.lesson-result h3{font-size:29px}.roy-cue b{font-size:46px}.roy-cue small{font-size:9px}.roy-cue>div{padding:15px 3px}.sample-caption{font-size:11px}.sample-pages{grid-template-columns:1fr;gap:26px}.sample-page{display:grid;grid-template-columns:110px 1fr;column-gap:20px;align-content:start}.sample-page .page-image{grid-row:1/6;height:155px;padding:9px;margin:0}.sample-page .page-number{font-size:9px;margin:5px 0 6px}.sample-page h3{font-size:17px}.sample-page p{font-size:13px}.page-open{margin-top:10px;justify-self:start;font-size:11px}.package-grid{grid-template-columns:1fr;gap:32px}.package-copy h2{font-size:32px}.package-items{margin-block:25px}.package-items>div{padding:19px 0}.package-items dd{font-size:14px}.topics-list ul{grid-template-columns:1fr}.purchase-panel{padding:28px}.purchase-price{font-size:44px}.purchase-panel .button{font-size:15px}.teacher-section{grid-template-columns:1fr;gap:30px}.teacher-section figure{max-width:220px}.teacher-section h2{font-size:35px}.teacher-section>div>p:not(.eyebrow):not(.teacher-signature){font-size:16px}.faq-list summary{font-size:15px}.closing-section{display:block;padding-block:48px}.closing-section .button{margin-top:26px;width:100%}.footer-row{display:block}.footer-row nav{margin-block:24px}.sample-viewer{width:100vw;height:100dvh;max-height:100dvh;max-width:100vw;border-radius:0;margin:0}.viewer-toolbar{height:64px;padding:12px 15px;gap:10px}.viewer-toolbar h2{font-size:14px}.viewer-toolbar button{font-size:12px;white-space:nowrap}.viewer-scroll{height:calc(100% - 64px);padding:8px}.viewer-scroll img{width:780px;max-width:none}.sample-page p{margin-top:0}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.button,.sample-page .page-image{transition:none}.book-frame{transform:none}}

/* Keep lesson results clear of the sticky navigation. */
.lesson-workspace,[data-question],[data-feedback]{scroll-margin-top:8px}
.answer-options label.is-wrong:has(input:checked){border-color:#bf754b;background:#fff6ee;box-shadow:inset 3px 0 #bf754b}
.answer-options label.is-correct:has(input:checked){border-color:#467b58;background:#eef6ef;box-shadow:inset 3px 0 #467b58}


[data-zoom-viewer]{display:none}
@media(max-width:560px){[data-zoom-viewer]{display:inline-block}.viewer-toolbar{gap:8px}.viewer-toolbar h2{flex:1;font-size:12px}.viewer-toolbar button{padding:8px 10px;font-size:11px}.viewer-scroll img{width:100%;max-width:100%}.sample-viewer.is-zoomed .viewer-scroll img{width:780px;max-width:none}}