.source-textbook-detail{overflow:hidden}.source-book-intro{background:var(--source-paper);grid-template-columns:400px minmax(0,1fr);min-height:980px;display:grid}.source-book-cover{background:#f1f2f3;justify-content:center;align-items:flex-start;padding:72px 28px;display:flex}.source-book-cover img{border-radius:8px;width:100%;height:auto;display:block;box-shadow:0 18px 44px #26262c1f}.source-book-intro-copy{justify-content:center;padding:222px 64px 112px;display:flex}.source-book-intro-inner{width:min(760px,100%)}.source-book-level{color:var(--source-orange);margin-bottom:12px;font-size:17px;font-weight:700}.source-book-intro h1{letter-spacing:-.055em;margin-bottom:12px;font-size:clamp(52px,5vw,72px);line-height:1.12}.source-book-intro-copy>div>h2{margin-bottom:22px;font-size:22px;line-height:1.45}.source-book-summary{color:#5e606e;font-size:16px;line-height:1.9}.source-book-contents{margin-top:52px}.source-book-contents>h2{margin-bottom:18px;font-size:22px}.source-book-contents details{background:var(--source-white);border:1px solid #eeeff1;border-radius:6px;margin-bottom:10px}.source-book-contents summary{color:#42434d;cursor:pointer;align-items:center;gap:10px;min-height:54px;padding:10px 40px 10px 12px;font-size:16px;font-weight:700;list-style-position:outside;display:flex}.source-book-contents summary>span{color:#42434d;background:#eeeff1;border-radius:4px;flex:0 0 82px;justify-content:center;align-items:center;min-height:30px;padding:4px 8px;font-size:13px;font-weight:600;display:inline-flex}.source-book-contents details:last-child summary>span{color:#ec6918;background:#fce6d9}.source-book-contents ol{color:#5e606e;columns:2;column-gap:42px;margin:0;padding:2px 32px 18px 58px}.source-book-contents li{break-inside:avoid;padding:3px 0;font-size:14px;line-height:1.65}.source-book-problems,.source-book-proof,.source-book-reasons,.source-book-features,.source-book-reviews,.source-book-courses{padding:120px 32px}.source-book-narrow{width:min(1040px,100%)}.source-book-problems{background:var(--source-paper);text-align:center}.source-book-question{object-fit:contain;width:110px;height:110px;margin-bottom:22px}.source-book-problems h2,.source-book-section-heading h2,.source-book-reasons>div>h2,.source-book-courses>div>h2{letter-spacing:-.045em;font-size:clamp(38px,4.2vw,58px);line-height:1.22}.source-book-problems h2{max-width:760px;margin:0 auto 58px}.source-book-problem-grid{text-align:left;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px;display:grid}.source-book-problem-grid article{background:var(--source-white);border-radius:16px;min-height:280px;padding:38px}.source-book-problem-grid h3{letter-spacing:-.025em;margin:0 0 20px;font-size:22px;line-height:1.45}.source-book-problem-grid p,.source-book-reason-grid p,.source-book-course-grid p{color:var(--source-muted);font-size:15px;line-height:1.8}.source-book-proof{background:var(--source-white)}.source-book-proof>.source-container{grid-template-columns:minmax(220px,.82fr) repeat(2,minmax(0,1.4fr));align-items:stretch;gap:20px;display:grid}.source-book-section-heading{margin:0;padding-right:18px;display:block}.source-book-section-heading>p{color:var(--source-muted);margin-top:28px;margin-bottom:0;font-size:14px;line-height:1.8}.source-book-proof .source-book-section-heading h2{font-size:clamp(30px,2.35vw,40px)}.source-book-achievement-grid{display:contents}.source-book-achievement-grid article{background:#e8e9eb;border-radius:24px;min-height:360px;position:relative;overflow:hidden}.source-book-achievement-grid article:after{content:"";background:linear-gradient(#0000,#000000b8);position:absolute;inset:45% 0 0}.source-book-achievement-grid img{object-fit:cover}.source-book-achievement-grid article>div{z-index:1;color:var(--source-white);position:absolute;bottom:30px;left:32px;right:32px}.source-book-achievement-grid strong,.source-book-achievement-grid span{display:block}.source-book-achievement-grid strong{margin-bottom:7px;font-size:22px;line-height:1.4}.source-book-achievement-grid span{font-size:14px}.source-book-reasons{background:var(--source-white)}.source-book-reasons>div>h2{margin-bottom:62px}.source-book-reason-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:64px 84px;display:grid}.source-book-reason-grid article>span{background:var(--source-orange);width:40px;height:40px;color:var(--source-white);border-radius:50%;place-items:center;margin-bottom:24px;font-weight:800;display:grid}.source-book-reason-grid article{background:var(--source-paper);border-radius:8px;padding:34px}.source-book-reason-grid h3{letter-spacing:-.035em;max-width:360px;margin:0 0 16px;font-size:30px;line-height:1.25}.source-book-features{background:var(--source-white);text-align:center;padding-top:88px;padding-bottom:100px}.source-book-features h2{margin-bottom:38px;font-size:42px}.source-book-feature-grid{grid-template-columns:repeat(4,minmax(0,1fr));gap:26px;display:grid}.source-book-feature-grid img{width:min(150px,80%);height:auto;margin-bottom:8px}.source-book-feature-grid h3{color:var(--source-orange);word-break:keep-all;margin:0 auto;font-size:16px;line-height:1.55}.source-book-reviews{background:var(--source-paper)}.source-book-section-heading.is-centered{text-align:center;margin-bottom:62px;padding-right:0;display:block}.source-book-section-heading.is-centered>p{color:var(--source-orange);margin-bottom:10px;font-weight:700}.source-book-section-heading.is-centered h2{font-size:clamp(36px,4vw,52px)}.source-book-review-grid{scroll-snap-type:x mandatory;scrollbar-width:thin;gap:24px;width:min(680px,100%);margin-inline:auto;display:flex;overflow-x:auto}.source-book-review-grid blockquote{background:var(--source-white);scroll-snap-align:start;border-radius:14px;flex-direction:column;flex:0 0 100%;min-height:300px;margin:0;padding:30px;display:flex}.source-book-review-grid blockquote>span{height:54px;color:var(--source-orange);font-family:Georgia,serif;font-size:78px;line-height:1}.source-book-review-grid blockquote p{margin-bottom:32px;font-size:17px;font-weight:600;line-height:1.65}.source-book-review-grid cite{color:var(--source-muted);margin-top:auto;font-size:14px;font-style:normal}.source-book-courses{background:var(--source-white)}.source-book-courses>div>h2{margin-bottom:52px}.source-book-course-grid{scroll-snap-type:x mandatory;scrollbar-width:thin;gap:24px;display:flex;overflow-x:auto}.source-book-course-grid article{aspect-ratio:16/7.4;background:var(--source-ink);color:var(--source-white);scroll-snap-align:start;border-radius:16px;flex:0 0 100%;position:relative;overflow:hidden}.source-book-course-grid article:after{content:"";background:linear-gradient(#0000,#141418e0);position:absolute;inset:35% 0 0}.source-book-course-image{position:absolute;inset:0}.source-book-course-image img{object-fit:cover}.source-book-course-grid h3{z-index:1;margin:0;font-size:25px;position:absolute;bottom:112px;left:34px;right:34px}.source-book-course-grid p{z-index:1;color:#ffffffd6;-webkit-line-clamp:3;-webkit-box-orient:vertical;max-width:850px;margin:0;display:-webkit-box;position:absolute;bottom:30px;left:34px;right:34px;overflow:hidden}@media (max-width:991px){.source-book-intro{min-height:0;display:block}.source-book-cover{padding:32px 16px 30px}.source-book-cover img{width:min(100%,520px)}.source-book-intro-copy{padding:76px 24px 90px}.source-book-problems,.source-book-proof,.source-book-reasons,.source-book-features,.source-book-reviews,.source-book-courses{padding:84px 16px}.source-book-section-heading{display:block}.source-book-proof>.source-container{grid-template-columns:1fr 1fr}.source-book-proof .source-book-section-heading{grid-column:1/-1;margin-bottom:28px}.source-book-section-heading>p{max-width:640px;margin-top:26px}.source-book-feature-grid{grid-template-columns:repeat(2,minmax(0,1fr))}}@media (max-width:640px){.source-book-intro-copy{padding:62px 16px 72px}.source-book-intro h1{font-size:48px}.source-book-intro-copy>div>h2{font-size:19px}.source-book-summary{font-size:15px;line-height:1.8}.source-book-contents ol{columns:1;padding-left:48px}.source-book-problems h2,.source-book-section-heading h2,.source-book-reasons>div>h2,.source-book-courses>div>h2{font-size:32px}.source-book-problem-grid,.source-book-reason-grid,.source-book-proof>.source-container{grid-template-columns:1fr}.source-book-problem-grid article{min-height:0;padding:28px}.source-book-achievement-grid article{border-radius:16px;min-height:300px}.source-book-achievement-grid article>div{bottom:22px;left:22px;right:22px}.source-book-achievement-grid strong{font-size:19px}.source-book-reason-grid{gap:54px}.source-book-reason-grid h3{font-size:25px}.source-book-feature-grid{gap:36px 12px}.source-book-feature-grid img{width:120px}.source-book-feature-grid h3{font-size:14px}.source-book-review-grid{width:100%}.source-book-review-grid blockquote{min-height:250px}.source-book-course-image{aspect-ratio:auto}.source-book-course-grid article{aspect-ratio:auto;min-height:360px}.source-book-course-grid h3{bottom:118px;left:22px;right:22px}.source-book-course-grid p{bottom:24px;left:22px;right:22px}}