/* Brand palette follows step-academic.com. Fonts are bundled for portable hosting. */
:root{--navy:#102c61;--blue:#173b78;--mint:#efe1c5;--beige:#efe1c5;--beige-soft:#f8f1e5;--ink:#15233a;--muted:#536176;--line:#e1e6ef;font-family:Cairo,Tahoma,Arial,sans-serif;color:var(--ink);background:#f6f8fc}
html:lang(he){font-family:Heebo,Arial,sans-serif}html{scroll-padding-top:110px}body{line-height:1.9}button,input,select{font-family:inherit}h1,h2,h3,p,span{overflow-wrap:break-word}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline-color:#ad792e}
.topbar{min-height:92px;height:auto;padding-block:15px;padding-inline:clamp(20px,4vw,64px);gap:20px;background:#fff}.brand{gap:12px;flex-shrink:0}.brand-logo{width:52px;height:54px;object-fit:contain;border-radius:11px;background:var(--beige)}.brand strong{color:var(--navy);font-size:19px;letter-spacing:0}.brand small{color:#756140;font-size:13px}.header-middle{display:none}.header-actions{align-items:center;gap:12px}.language-picker button{font-size:14px;min-height:38px}.welcome-nav{display:flex;gap:26px;align-items:center;font-size:14px;font-weight:700}.welcome-nav a{text-decoration:none;color:var(--navy)}.welcome-nav a:hover{color:#806132}.header-home{color:var(--navy);text-decoration:none;font-weight:700;font-size:14px}.is-welcome .header-home{display:none}body:not(.is-welcome) .welcome-nav{display:none}.is-welcome .index-toggle{display:none}
.primary-button{background:var(--navy);box-shadow:none;font-size:15px;font-weight:700;border-radius:11px;padding:13px 22px;display:inline-flex;align-items:center;justify-content:center;gap:22px}.primary-button:hover{background:#173b78}.secondary-button{color:var(--navy);font-size:14px;border-color:#ced7e6}.text-button,.eyebrow{color:var(--navy)}.chapter-link[aria-current=true]{background:var(--beige-soft);color:var(--navy);box-shadow:inset -3px 0 var(--navy)}.chapter-link:hover{background:#f4f6fa}.lesson-tabs [aria-selected=true]{color:var(--navy);border-color:var(--navy)}.author-monogram{background:var(--beige);color:var(--navy)}.formula-block{background:#edf3fb;color:var(--navy)}.answer-label input{accent-color:var(--navy)}.answer-label:has(input:checked){border-color:var(--navy);background:#edf3fb}.breadcrumbs,.sidebar-title p,.page-footer,.page-footer .text-button{font-size:14px}.reading-card p,.reading-card li{line-height:2.1}
.welcome{max-width:none;margin:0;padding:0;background:#fff;overflow:hidden}.welcome-container{width:min(1180px,calc(100% - 64px));margin-inline:auto}.welcome p{margin:0 0 20px}.welcome h1,.welcome h2,.welcome h3{letter-spacing:0;line-height:1.6}.welcome-eyebrow{font-size:14px;font-weight:700;color:#806132;margin:0 0 15px!important}.welcome-eyebrow span{padding-inline:10px;opacity:.6}.welcome-hero{background:linear-gradient(150deg,#fff 55%,#f8f1e5 100%)}.welcome-hero-grid{display:grid;grid-template-columns:1.2fr 1fr;align-items:center;gap:68px;padding-block:68px 60px}.welcome h1{font-size:clamp(38px,4.5vw,66px);line-height:1.45;color:var(--navy);font-weight:900;margin:0 0 26px}.welcome h1>span{color:#896b3b}.welcome-lead{font-size:18px;line-height:2.05;color:var(--muted);max-width:570px}.welcome-actions{display:flex;align-items:center;gap:28px;flex-wrap:wrap;margin-top:30px}.welcome-text-link{font-weight:700;font-size:15px;color:var(--navy);text-decoration-thickness:1px;text-underline-offset:6px}.welcome-byline{display:flex;align-items:center;gap:15px;margin-top:36px;padding-top:26px;border-top:1px solid var(--line);text-decoration:none;width:fit-content}.welcome-monogram{width:56px;height:56px;display:grid;place-items:center;background:var(--beige);color:var(--navy);border-radius:50%;font:700 21px Georgia,serif;flex-shrink:0}.welcome-byline>span:last-child{display:flex;flex-wrap:wrap;column-gap:7px;max-width:390px}.welcome-byline small{font-size:14px;color:var(--muted);align-self:center}.welcome-byline strong{font-size:18px;color:var(--navy)}.welcome-byline>span>span{font-size:14px;color:var(--muted);flex-basis:100%}
.welcome-example{position:relative;background:var(--navy);color:#fff;border-radius:24px;padding:30px 34px 26px;box-shadow:0 24px 60px #102c611c;align-self:center;border-top:5px solid var(--beige);min-width:0}.welcome-example-top{display:flex;justify-content:space-between;gap:15px;color:#ecdfc8;font-size:13px;padding-bottom:22px;border-bottom:1px solid #ffffff2b}.welcome .welcome-example h2{font-size:27px;line-height:1.7;margin:22px 0 9px;color:#fff}.welcome-example>p{color:#d2dced;font-size:15px;line-height:1.95}.welcome-equation{font:italic 64px/1.6 Georgia,serif;text-align:center;color:var(--beige);padding-block:5px;margin:20px 0;border-block:1px solid #ffffff2b;letter-spacing:2px}.welcome-equation span{font-style:normal;color:#cad5e7;font-size:42px}.welcome-example-values{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));margin:0;text-align:center}.welcome-example-values>div+div{border-inline-start:1px solid #ffffff2b}.welcome-example-values dt{font-size:14px;color:#d2dced}.welcome-example-values dd{margin:7px 0 0;font:700 26px/1.4 Arial,sans-serif}.welcome-example-values small{font-weight:400;font-size:17px}.welcome-example .welcome-example-note{font-size:13px;text-align:center;margin:21px 0;color:#d2dced}.welcome-example-button{display:flex;justify-content:space-between;gap:20px;align-items:center;width:100%;padding:15px 0 0;color:var(--beige);border:0;border-top:1px solid #ffffff2b;background:transparent;font-size:15px;font-weight:700}.welcome-example-button:hover{color:white}.welcome-facts{border-top:1px solid #d9dfe7;display:grid;grid-template-columns:repeat(3,minmax(0,1fr));padding-block:26px 30px}.welcome-facts>div{display:flex;justify-content:center;align-items:center;gap:17px}.welcome-facts>div+div{border-inline-start:1px solid #d9dfe7}.welcome-facts strong{font:700 28px/1.3 Arial,sans-serif;color:var(--navy)}.welcome-facts span{font-size:14px;color:var(--muted)}
.welcome-section{padding-block:85px}.welcome-section-heading{max-width:800px;margin-bottom:28px}.welcome h2{font-size:clamp(28px,3vw,42px);font-weight:900;color:var(--navy);margin:0 0 18px}.welcome-book-copy{display:grid;grid-template-columns:1.2fr 1fr;gap:65px;color:var(--muted);font-size:17px;line-height:2.05}.welcome-methods{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:38px;margin-top:32px}.welcome-methods article{position:relative;border-top:2px solid var(--beige);padding-top:21px;padding-inline-end:12px}.welcome-methods article>span{font:400 14px/1.8 Arial,sans-serif;color:#806132}.welcome-methods h3{color:var(--navy);font-size:22px;margin:8px 0}.welcome-methods p{font-size:16px;color:var(--muted);margin-bottom:0}.welcome-author-section{padding-block:80px;background:var(--beige-soft);border-block:1px solid #efe1c5}.welcome-author-grid{display:grid;grid-template-columns:.85fr 1.2fr;gap:80px}.welcome-author-heading h2{font-size:clamp(35px,4vw,53px);line-height:1.5;margin-bottom:12px}.welcome-author-subtitle{font-size:19px;color:#806132}.welcome-credentials{margin:30px 0 0;border-top:1px solid #dcd2bf}.welcome-credentials>div{padding-block:18px;border-bottom:1px solid #dcd2bf}.welcome-credentials dt{font-size:14px;font-weight:700;color:#806132}.welcome-credentials dd{margin:5px 0 0;font-size:16px;color:var(--navy)}.welcome-bio{font-size:17px;color:#435169;line-height:2.1;padding-top:6px}.welcome-author-note{border-inline-start:3px solid #b4955f;padding-inline-start:26px;margin-top:32px}.welcome-author-note h3{font-size:20px;color:var(--navy);margin:0 0 12px}.welcome-author-note p{font-size:16px}.welcome-author-note strong{font-size:16px;color:var(--navy)}
.welcome-chapters-heading{display:flex;align-items:center;justify-content:space-between;gap:35px;margin-bottom:30px}.welcome-chapters-heading p:not(.welcome-eyebrow){font-size:16px;color:var(--muted)}.welcome-chapters-heading>.primary-button{flex-shrink:0}.welcome-chapters-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));column-gap:44px;row-gap:28px;align-items:start}.welcome-chapter-group h3{margin:0 0 8px;display:flex;justify-content:space-between;align-items:center;gap:12px;color:var(--navy);font-size:19px;padding:16px 20px;background:#edf3fb;border-radius:10px}.welcome-chapter-group h3 span{font:400 15px Arial,sans-serif;color:var(--muted)}.welcome-chapter{display:flex;align-items:center;gap:17px;width:100%;border:0;border-bottom:1px solid var(--line);background:transparent;text-align:start;padding:17px 12px;color:var(--ink);font-size:15px;line-height:1.9}.welcome-chapter:hover{background:var(--beige-soft)}.welcome-chapter-number{color:#806132;font:400 14px Arial,sans-serif;min-width:23px}.welcome-chapter-arrow{margin-inline-start:auto;color:#806132;flex-shrink:0}.welcome-curriculum-note{font-size:14px;color:var(--muted);padding-top:25px;margin-bottom:0!important}.welcome-footer{background:var(--navy);color:#fff;padding-block:28px}.welcome-footer>.welcome-container{display:flex;align-items:center;justify-content:space-between;gap:26px}.welcome-footer-brand{display:flex;gap:12px;align-items:center;text-decoration:none}.welcome-footer-brand img{width:48px;height:50px;object-fit:contain;border-radius:9px}.welcome-footer-brand strong,.welcome-footer-brand small{display:block}.welcome-footer-brand small{font-size:13px;color:var(--beige)}.welcome-footer p{font-size:14px;color:#d2dced;margin:0}.welcome-footer a:last-child{font-size:14px;text-underline-offset:5px}.welcome section[id]{scroll-margin-top:30px}
@media(min-width:1500px){.welcome-container{width:min(1280px,calc(100% - 100px))}.welcome-hero-grid{gap:100px;padding-block:85px 70px}}
@media(max-width:1100px){.welcome-nav{gap:17px}.welcome-hero-grid{gap:36px}.welcome-example{padding-inline:27px}.welcome .welcome-example h2{font-size:25px}.welcome-author-grid{gap:45px}.welcome-book-copy{gap:35px}.header-actions{gap:8px}.topbar{padding-inline:24px}}
@media(max-width:980px){.welcome-nav{display:none}.welcome-hero-grid{gap:28px}.welcome-container{width:calc(100% - 44px)}.welcome-hero-grid{padding-block:45px}.welcome h1{font-size:42px}.welcome-lead{font-size:16px}.welcome-actions{gap:18px}.welcome-actions .primary-button{font-size:14px;padding-inline:17px}.welcome-example{padding:24px}.welcome .welcome-example h2{font-size:24px}.welcome-equation{font-size:54px}.welcome-facts>div{flex-direction:column;gap:6px}.welcome-section{padding-block:60px}.welcome-author-section{padding-block:60px}.welcome-chapters-heading{align-items:flex-start}.welcome-chapters-heading>.primary-button{font-size:14px}.welcome-chapters-grid{column-gap:26px}.welcome-bio{font-size:16px}.header-home{font-size:14px}}
@media(max-width:720px){.topbar{padding:12px 18px;gap:10px;min-height:80px}.brand-logo{width:43px;height:45px}.brand{gap:9px}.brand strong{font-size:16px}.brand small{font-size:12px}.language-picker button{font-size:14px;padding:4px 9px;min-height:36px}.header-actions{gap:6px}.header-home{font-size:13px}.welcome-hero-grid{grid-template-columns:1fr;gap:32px;padding-block:38px}.welcome h1{font-size:clamp(36px,7.5vw,51px);margin-bottom:20px}.welcome-lead{font-size:17px}.welcome-example{width:100%;max-width:520px;justify-self:center;padding:26px 28px}.welcome .welcome-example h2{font-size:26px}.welcome-equation{font-size:60px;margin-block:16px}.welcome-byline{margin-top:26px;padding-top:20px}.welcome-facts{padding-block:22px}.welcome-facts strong{font-size:23px}.welcome-facts span{font-size:13px;text-align:center;line-height:1.8}.welcome-facts>div{padding-inline:9px}.welcome-book-copy,.welcome-author-grid{grid-template-columns:1fr;gap:18px}.welcome-methods{grid-template-columns:1fr;gap:22px;margin-top:22px}.welcome-methods article{padding-top:16px;padding-inline-start:44px}.welcome-methods article>span{position:absolute;inset-inline-start:0;top:23px}.welcome-methods h3{margin-top:0}.welcome-author-grid{gap:28px}.welcome-credentials{margin-top:24px}.welcome-credentials>div{padding-block:13px}.welcome-author-note{padding-inline-start:20px}.welcome-chapters-heading{display:block}.welcome-chapters-heading>.primary-button{margin-top:8px}.welcome-chapters-grid{grid-template-columns:1fr;gap:30px}.welcome-footer>.welcome-container{flex-direction:column;align-items:flex-start;gap:18px}.welcome-container{width:calc(100% - 36px)}.welcome-eyebrow{font-size:13px}.welcome-chapter{font-size:15px;padding-block:16px}.welcome-section,.welcome-author-section{padding-block:45px}body:not(.is-welcome) .header-home{display:none}.sidebar.open{top:80px}.welcome h2{font-size:30px}.welcome-author-heading h2{font-size:39px}}
@media(max-width:380px){.topbar{padding-inline:12px}.brand-logo{width:37px;height:39px}.brand strong{font-size:15px}.brand small{font-size:12px}.language-picker button{padding-inline:6px}.welcome-container{width:calc(100% - 28px)}.welcome h1{font-size:34px}.welcome-example{padding-inline:22px}.welcome-facts strong{font-size:20px}.welcome-byline>span>span{font-size:13px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.welcome *{animation:none!important;transition:none!important}}

.institute-return{
  text-decoration:none;border:1px solid #d7e0ea;border-radius:9px;
  padding:7px 12px;color:#102c61;background:#fff;font-size:12px;font-weight:700;
  white-space:nowrap
}
.institute-return:hover{background:#f6f8fc}
@media(max-width:760px){.institute-return{display:none}}