.curriculum-page{--course-ink:#25332e;--course-muted:#65736c;--course-line:#e5e9df;--course-paper:#fffefa;background:#f6f7f1;color:var(--course-ink)}
.course-main{width:min(1120px,calc(100% - 56px));margin:0 auto 70px}.course-hero{position:relative;isolation:isolate;display:grid;grid-template-columns:minmax(0,1fr) 310px;align-items:center;gap:45px;min-height:355px;margin:28px 0 20px;padding:52px 56px;overflow:hidden;border:1px solid #e4e9de;border-radius:30px;background:linear-gradient(118deg,#fffefa 0%,#f3f7ed 60%,#e8f2ea 100%);box-shadow:0 18px 46px rgba(52,73,61,.06)}
.course-hero-copy{position:relative;z-index:1;max-width:700px}.course-eyebrow,.course-kicker{display:block;color:#53806d;font-size:12px;font-weight:900;letter-spacing:.08em}.course-eyebrow{display:flex;align-items:center;gap:9px}.course-eyebrow i{width:8px;height:8px;border-radius:50%;background:#6ea585;box-shadow:0 0 0 5px #e5f0e5}.course-hero h1{margin:14px 0 13px;font-size:clamp(35px,5.3vw,55px);line-height:1.16;letter-spacing:-.05em}.course-hero h1 em{color:#54876f;font-style:normal}.course-hero-copy>p{max-width:650px;margin:0;color:#5c6b64;font-size:15px;line-height:1.95}.course-hero-actions{display:flex;align-items:center;flex-wrap:wrap;gap:19px;margin-top:22px}.course-button{display:inline-flex;align-items:center;gap:12px;padding:12px 18px;border-radius:999px;background:#2d594c;color:white;font-size:13px;font-weight:900;text-decoration:none;box-shadow:0 6px 16px rgba(45,89,76,.17)}.course-button:hover{background:#23483d}.course-text-link{color:#4f7465;font-size:12px;font-weight:900;text-decoration:none}.course-text-link:hover{text-decoration:underline;text-underline-offset:4px}.course-principles{display:flex;flex-wrap:wrap;gap:8px;margin-top:22px}.course-principles span{padding:6px 10px;border:1px solid #e2e9dc;border-radius:99px;background:rgba(255,255,255,.7);color:#647369;font-size:10px;font-weight:800}
.mastery-card{position:relative;z-index:1;padding:22px;border:1px solid rgba(220,231,217,.95);border-radius:22px;background:rgba(255,255,252,.88);box-shadow:0 13px 32px rgba(59,77,62,.07)}.mastery-card-top{display:flex;align-items:center;justify-content:space-between;gap:10px;color:#627067;font-size:12px;font-weight:800}.mastery-card-top b{color:#2e674f;font-size:17px}.mastery-track{height:9px;margin:16px 0 12px;overflow:hidden;border-radius:99px;background:#e8eee4}.mastery-track span{display:block;width:0;height:100%;border-radius:inherit;background:linear-gradient(90deg,#79af89,#447f65);transition:width .25s}.mastery-card p{min-height:42px;margin:0 0 10px;color:#596a60;font-size:12px;line-height:1.75}.mastery-card small{color:#8a948d;font-size:10px}.course-orbit{position:absolute;z-index:-1;display:grid;place-items:center;border:1px solid rgba(128,170,136,.19);border-radius:50%;color:rgba(71,127,94,.15);font-weight:900}.orbit-one{width:240px;height:240px;right:255px;top:-120px;font-size:130px}.orbit-two{width:180px;height:180px;right:40px;bottom:-123px;font-size:100px}
.course-guide{display:flex;align-items:center;justify-content:space-between;gap:20px;margin:0 0 45px;padding:16px 20px;border:1px solid #e7eadf;border-radius:16px;background:#fffefa}.course-guide>div{display:flex;align-items:center;gap:13px}.course-guide b{flex:0 0 auto;color:#3b7059;font-size:12px}.course-guide span{color:#68746d;font-size:12px;line-height:1.7}.course-guide>a{flex:0 0 auto;color:#3d7963;font-size:11px;font-weight:900;text-decoration:none}.course-guide>a:hover{text-decoration:underline;text-underline-offset:3px}
.curriculum-browser{scroll-margin-top:85px}.browser-heading{display:flex;align-items:end;justify-content:space-between;gap:20px;margin-bottom:18px}.course-kicker{font-size:10px;letter-spacing:.12em}.browser-heading h2{margin:6px 0 0;font-size:26px;letter-spacing:-.035em}.visible-count{padding:7px 11px;border:1px solid var(--course-line);border-radius:99px;background:#fffefa;color:#66766b;font-size:11px;font-weight:800;white-space:nowrap}.browser-controls{display:grid;grid-template-columns:minmax(240px,1fr) 260px auto;align-items:center;gap:12px;margin-bottom:25px;padding:13px;border:1px solid #e7e9e0;border-radius:18px;background:#fffefa}.search-control{display:flex;align-items:center;gap:9px;min-width:0;padding:0 12px;border:1px solid #e7eae2;border-radius:11px;background:#fbfcf8}.search-control>span{color:#72917e;font-size:20px}.search-control input{width:100%;min-width:0;height:39px;border:0;outline:none;background:transparent;color:#27332e;font:inherit;font-size:12px}.search-control input::placeholder{color:#99a39b}.branch-control{display:flex;align-items:center;gap:10px;color:#79847d;font-size:10px;font-weight:800}.branch-control select{width:100%;height:40px;padding:0 10px;border:1px solid #e7eae2;border-radius:10px;background:#fbfcf8;color:#35443b;font:inherit;font-size:11px}.incomplete-control{display:flex;align-items:center;gap:8px;padding:0 8px;color:#627168;font-size:11px;font-weight:800;white-space:nowrap;cursor:pointer}.incomplete-control input{width:16px;height:16px;accent-color:#52856a}
.curriculum-branch{margin:0 0 34px;scroll-margin-top:84px}.branch-heading{display:flex;align-items:center;gap:13px;margin:0 0 13px;padding:0 2px}.branch-icon{display:grid;flex:0 0 43px;width:43px;height:43px;place-items:center;border:1px solid rgba(97,130,104,.12);border-radius:15px;background:#e9f1e8;color:#3f7156;font-size:13px;font-weight:900}.branch-heading>div>p{margin:0;color:#6e8b75;font-size:10px;font-weight:900;letter-spacing:.09em}.branch-heading h2{display:inline-block;margin:2px 9px 0 0;font-size:20px;letter-spacing:-.03em}.branch-heading>div>span{color:#758079;font-size:11px;line-height:1.7}.branch-peach .branch-icon{background:#fff0e8;color:#aa684c}.branch-lilac .branch-icon{background:#f0ebf8;color:#7867a2}.branch-blue .branch-icon{background:#e8f1f7;color:#527a92}.branch-green .branch-icon{background:#e8f2e9;color:#4c7c58}.branch-gold .branch-icon{background:#f8f0dd;color:#927841}
.lesson-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.lesson-unit{min-width:0;border:1px solid #e7e9e0;border-radius:15px;background:#fffefa;box-shadow:0 5px 16px rgba(44,61,50,.035);transition:border-color .2s,box-shadow .2s}.lesson-unit:hover{border-color:#d4e1d2;box-shadow:0 8px 22px rgba(44,61,50,.065)}.lesson-unit.is-mastered{border-color:#cce1cf;background:#fdfffc}.lesson-fold>summary{display:grid;grid-template-columns:35px minmax(0,1fr) auto 18px;align-items:center;gap:10px;min-height:75px;padding:12px 14px;cursor:pointer;list-style:none}.lesson-fold>summary::-webkit-details-marker{display:none}.lesson-symbol{display:grid;width:34px;height:34px;place-items:center;border-radius:12px;background:#f0f3eb;color:#64816b;font-size:10px;font-weight:900}.branch-peach .lesson-symbol{background:#fff3eb;color:#b67759}.branch-blue .lesson-symbol{background:#eef5f8;color:#66859a}.branch-lilac .lesson-symbol{background:#f3eff9;color:#806fa5}.lesson-name{display:flex;min-width:0;flex-direction:column;gap:4px}.lesson-name small{display:flex;align-items:center;flex-wrap:wrap;gap:5px;color:#839087;font-size:9px;font-weight:800}.lesson-name>b{overflow:hidden;color:#2c3832;font-size:13px;text-overflow:ellipsis;white-space:nowrap}.source-tag{padding:3px 6px;border-radius:99px;background:#f4f1e8;color:#92805b;font-size:8px;font-weight:800}.lesson-state{color:#728176;font-size:9px;font-weight:800;white-space:nowrap}.is-mastered .lesson-state{color:#3c815e}.fold-mark{color:#89a48e;font-size:15px;text-align:center}.lesson-fold[open] .fold-mark{transform:rotate(45deg)}
.lesson-body{padding:1px 15px 16px;border-top:1px solid #eff0ea}.learn-block{padding:13px 0 3px}.learn-block h3,.example-block h3,.practice-title h3{margin:0;color:#33443a;font-size:12px}.learn-block p{margin:6px 0 2px;color:#59675f;font-size:11px;line-height:1.85}.example-block{margin:10px 0;padding:12px 13px;border:1px solid #e7ece0;border-radius:12px;background:#f7f9f2}.block-label{display:block;margin-bottom:5px;color:#62806b;font-size:9px;font-weight:900;letter-spacing:.1em}.example-block h3{font-size:12px;line-height:1.7}.example-block p{margin:6px 0 0;color:#647269;font-size:10px;line-height:1.8}.practice-block{margin-top:14px}.practice-title{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-bottom:7px}.practice-title h3{font-size:13px}.practice-count{padding:4px 8px;border-radius:99px;background:#f0f4ec;color:#6b7f6e;font-size:9px;font-weight:900;white-space:nowrap}.question-unit{padding:11px 0;border-top:1px solid #eef0e9}.question-unit>label{display:flex;align-items:flex-start;gap:8px;color:#3e4a43;font-size:11px;line-height:1.7;cursor:pointer}.question-unit>label>b{display:grid;flex:0 0 19px;width:19px;height:19px;place-items:center;border-radius:7px;background:#edf2e8;color:#64836b;font-size:9px}.answer-row{display:flex;gap:7px;margin:8px 0 0 27px}.answer-row input{width:min(180px,70%);height:34px;padding:0 10px;border:1px solid #dde5db;border-radius:9px;outline:none;background:white;color:#27342d;font:inherit;font-size:12px}.answer-row input:focus{border-color:#73a285;box-shadow:0 0 0 3px #eaf3e9}.answer-row button{padding:0 12px;border:0;border-radius:9px;background:#e8f1e6;color:#3d7053;font:inherit;font-size:10px;font-weight:900;cursor:pointer}.answer-row button:hover{background:#dbe9d9}.answer-feedback{min-height:16px;margin:5px 0 0 28px;color:#a16b4b;font-size:10px;line-height:1.6}.answer-feedback.good{color:#3d805d}.solution-fold{margin:0 0 0 27px;color:#6c776f;font-size:10px;line-height:1.8}.solution-fold summary{width:max-content;max-width:100%;color:#728a70;font-weight:900;cursor:pointer}.solution-fold p{margin:5px 0}.solution-fold p+b{margin-top:8px}.deeper-link{display:flex;align-items:center;justify-content:space-between;margin-top:15px;padding:10px 12px;border-radius:10px;background:#f2f5ed;color:#426f59;font-size:10px;font-weight:900;text-decoration:none}.deeper-link:hover{background:#e9f0e5}.mastery-note{margin:10px 0 0;color:#89928b;font-size:9px;line-height:1.65}.empty-state{display:flex;flex-direction:column;align-items:center;gap:7px;margin:24px 0;padding:42px 20px;border:1px dashed #dbe2d8;border-radius:18px;background:#fffefa;color:#758178;font-size:12px}.empty-state b{color:#4b5e50;font-size:14px}
.course-bottom{display:flex;align-items:center;justify-content:space-between;gap:24px;margin-top:46px;padding:26px 29px;border:1px solid #e4e9df;border-radius:20px;background:linear-gradient(120deg,#eef4e9,#fffefa)}.course-bottom h2{margin:5px 0 7px;font-size:17px}.course-bottom p{max-width:730px;margin:0;color:#69766d;font-size:11px;line-height:1.8}.course-bottom>a{flex:0 0 auto;display:flex;align-items:center;gap:12px;padding:12px 15px;border-radius:99px;background:#2d594c;color:white;font-size:11px;font-weight:900;text-decoration:none}.course-bottom>a:hover{background:#23483d}.course-footer{margin-top:0}.course-footer .brand-mark{display:grid;place-items:center}
@media(max-width:850px){.course-main{width:min(100% - 38px,760px)}.course-hero{grid-template-columns:minmax(0,1fr) 250px;gap:20px;padding:38px 32px}.browser-controls{grid-template-columns:minmax(180px,1fr) 220px}.incomplete-control{grid-column:1/-1;padding:4px 5px}.lesson-grid{gap:8px}}
@media(max-width:650px){.course-main{width:calc(100% - 28px);margin-bottom:42px}.course-hero{grid-template-columns:1fr;gap:18px;min-height:0;margin:15px 0 13px;padding:27px 21px;border-radius:22px}.course-hero h1{font-size:36px}.course-hero-copy>p{font-size:12px;line-height:1.85}.course-principles{gap:6px;margin-top:16px}.course-principles span{padding:5px 7px;font-size:9px}.mastery-card{padding:16px}.mastery-card p{min-height:0}.orbit-one{right:-22px;top:-100px}.orbit-two{right:-10px;bottom:-100px}.course-guide{align-items:flex-start;flex-direction:column;gap:8px;margin-bottom:33px;padding:13px 14px}.course-guide>div{align-items:flex-start;flex-direction:column;gap:4px}.course-guide span{font-size:10px}.browser-heading{align-items:flex-start;flex-direction:column;gap:8px}.browser-heading h2{font-size:22px}.visible-count{padding:5px 8px;font-size:9px}.browser-controls{grid-template-columns:1fr;gap:9px;padding:10px}.search-control input{height:37px}.branch-control{display:grid;grid-template-columns:70px 1fr}.incomplete-control{grid-column:auto}.curriculum-branch{margin-bottom:26px}.branch-heading{align-items:flex-start;gap:10px}.branch-icon{flex-basis:37px;width:37px;height:37px;border-radius:12px}.branch-heading h2{font-size:17px}.branch-heading>div>span{display:block;margin-top:3px;font-size:10px}.lesson-grid{grid-template-columns:1fr}.lesson-fold>summary{min-height:66px;padding:10px 11px;grid-template-columns:32px minmax(0,1fr) auto 13px;gap:8px}.lesson-symbol{width:31px;height:31px}.lesson-name>b{font-size:12px}.lesson-state{font-size:8px}.lesson-body{padding-right:12px;padding-left:12px}.course-bottom{align-items:flex-start;flex-direction:column;margin-top:32px;padding:19px}.course-bottom h2{font-size:15px;line-height:1.6}.course-footer{align-items:center;gap:9px}.course-footer>span:nth-child(2){display:none}}
@media(prefers-reduced-motion:reduce){.curriculum-page *{scroll-behavior:auto!important;transition:none!important}}

.branch-study-link{display:inline-flex;align-items:center;gap:8px;width:max-content;max-width:100%;margin-top:9px;padding:8px 10px;border:1px solid #dce8d8;border-radius:10px;background:#f1f6ed;color:#3f7653;font-size:10px;font-weight:900;text-decoration:none}.branch-study-link:hover{border-color:#b9d2b7;background:#e8f1e5}.branch-study-link span{font-size:14px}@media(max-width:650px){.branch-study-link{margin-top:8px;font-size:9px}}

.curriculum-rich-math{display:block;box-sizing:border-box;width:fit-content;max-width:100%;margin:.38em 0;padding:.3em .62em;border-left:4px solid #7f9859;border-radius:0 9px 9px 0;background:#edf4e5;color:#344b38;font-size:clamp(14px,1.45vw,17px);font-weight:900;line-height:1.65;overflow-wrap:anywhere;white-space:normal;font-variant-numeric:lining-nums tabular-nums}
.curriculum-question-text{display:block;flex:1;min-width:0}
.example-block h3 .curriculum-rich-math{font-size:clamp(14px,1.4vw,16px)}
.solution-fold .curriculum-rich-math{font-size:14px}
@media(max-width:650px){.curriculum-rich-math{font-size:14px;margin:.32em 0;padding:.32em .55em}.example-block h3 .curriculum-rich-math{font-size:14px}}
@media(max-width:650px){body.curriculum-page:not(.textbook-page):not(.branch-course-page):not(.sequences-page) .topbar{height:auto;min-height:0;padding:10px 14px;gap:8px 12px;flex-wrap:wrap}body.curriculum-page:not(.textbook-page):not(.branch-course-page):not(.sequences-page) .nav-cta{order:1;margin-left:auto;flex:0 0 auto;white-space:nowrap}body.curriculum-page:not(.textbook-page):not(.branch-course-page):not(.sequences-page) .topnav{order:2;flex:1 0 100%;width:100%;min-width:0;justify-content:flex-start;gap:14px;margin-left:0;overflow-x:auto;white-space:nowrap;scrollbar-width:none;padding:0 0 2px}body.curriculum-page:not(.textbook-page):not(.branch-course-page):not(.sequences-page) .topnav::-webkit-scrollbar{display:none}body.curriculum-page:not(.textbook-page):not(.branch-course-page):not(.sequences-page) .topnav a{flex:0 0 auto;white-space:nowrap}}

.parity-concept{margin-top:8px;padding:13px;border:1px solid #e0e9dc;border-radius:13px;background:linear-gradient(145deg,#fbfcf7,#f5f8ef)}
.parity-intro{margin:0 0 10px;color:#435449;font-size:12px;font-weight:800;line-height:1.7}
.parity-definition-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px}
.parity-definition{display:flex;align-items:center;justify-content:space-between;min-width:0;padding:9px 11px;border:1px solid;border-radius:10px}
.parity-definition span{font-size:11px;font-weight:900}
.parity-definition strong{font-size:20px;line-height:1.35;font-variant-numeric:lining-nums}
.parity-definition.parity-even{border-color:#cce3d8;background:#e9f4ed;color:#246d5b}
.parity-definition.parity-odd{border-color:#f0d7c9;background:#fff0e8;color:#a65035}
.parity-note{margin:6px 0 12px;color:#77837a;font-size:9px;line-height:1.6}
.parity-label{margin:12px 0 7px;color:#40564a;font-size:11px;font-weight:900}
.parity-rule-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:7px}
.parity-rule{min-width:0;padding:9px 10px;border:1px solid #e4eade;border-radius:10px;background:#fffefa}
.parity-rule.parity-wide{grid-column:1/-1}
.parity-rule strong{display:block;color:#35463b;font-size:clamp(14px,4vw,17px);line-height:1.55;letter-spacing:.01em;overflow-wrap:anywhere}
.parity-rule small{display:block;margin-top:3px;color:#748077;font-size:9px;line-height:1.6}
.parity-odd{color:#a65035}.parity-even{color:#246d5b}
.parity-takeaway{margin:12px 0 0;padding:9px 10px;border-left:3px solid #6c9b76;border-radius:0 9px 9px 0;background:#eaf2e7;color:#3e634c;font-size:10px;font-weight:800;line-height:1.7}
.parity-example p{margin:6px 0;color:#647269;font-size:10px;line-height:1.7}
.parity-example-formula{display:flex;align-items:center;justify-content:center;flex-wrap:wrap;gap:10px;padding:8px 10px;border:1px solid #dce8d8;border-radius:9px;background:#eef5e9;color:#365c45;font-size:15px;line-height:1.5}
.parity-example-formula strong{font-variant-numeric:lining-nums;overflow-wrap:anywhere}
.parity-equation{margin-top:6px;background:#e5f1e6;font-size:16px}
@media(max-width:380px){.parity-concept{padding:10px}.parity-definition{padding:8px}.parity-rule-grid{grid-template-columns:1fr}.parity-rule{padding:8px}.parity-rule strong{font-size:14px}.parity-example-formula{gap:7px;padding:8px 7px;font-size:14px}.parity-equation{font-size:14px}}

/* Divisibility lesson: method choice, proof, and transfer */
.divisibility-guide{margin-top:8px;min-width:0}
.divisibility-definition{margin:0 0 10px;padding:10px 12px;border-left:4px solid #81965d;border-radius:0 10px 10px 0;background:#f1f5e9;color:#405044;font-size:11px;line-height:1.85;overflow-wrap:anywhere}
.divisibility-section-title{margin:12px 0 7px;color:#425648;font-size:11px;line-height:1.6}
.divisibility-route{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:7px;margin-bottom:12px}
.divisibility-route article{min-width:0;padding:9px 10px;border:1px solid #e4eadf;border-radius:10px;background:#fbfcf8}
.divisibility-route article b{color:#47745a;font-size:10px}
.divisibility-route article p{margin:5px 0 0;color:#68756c;font-size:10px;line-height:1.7;overflow-wrap:anywhere}
.divisibility-rule-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px}
.divisibility-rule{min-width:0;padding:10px 11px;border:1px solid #e6eae1;border-radius:11px;background:#fffefa}
.divisibility-rule header{display:flex;align-items:center;justify-content:space-between;gap:8px;margin-bottom:6px}
.divisibility-rule header h4{margin:0;color:#354b3c;font-size:11px}
.divisibility-rule header span{flex:0 0 auto;padding:3px 7px;border-radius:99px;background:#edf3e8;color:#5a795c;font-size:9px;font-weight:900}
.divisibility-rule p{margin:5px 0 0;color:#68746b;font-size:10px;line-height:1.7;overflow-wrap:anywhere}
.divisibility-rule p b{color:#4b6250}
.divisibility-rule-example{padding-top:5px;border-top:1px dashed #e8ece4}
.divisibility-fold{margin-top:9px;padding:9px 10px;border:1px solid #e4e9df;border-radius:10px;background:#f8faf5;color:#5e6e62;font-size:10px;line-height:1.75}
.divisibility-fold summary{color:#4f7558;font-weight:900;cursor:pointer}
.divisibility-fold-content{display:grid;gap:7px;margin-top:8px}
.divisibility-fold-content article{padding:8px 9px;border-radius:8px;background:#fffefa}
.divisibility-fold-content article b{color:#425746;font-size:10px}
.divisibility-fold-content article p{margin:4px 0 0;color:#66736a;font-size:10px;line-height:1.75;overflow-wrap:anywhere}
.divisibility-pitfalls{margin-top:10px;padding:10px 12px;border:1px solid #efe8d9;border-radius:10px;background:#fffaf1}
.divisibility-pitfalls h4{margin:0;color:#796541;font-size:10px}
.divisibility-pitfalls ul{display:grid;gap:4px;margin:6px 0 0;padding-left:18px;color:#766d5d;font-size:10px;line-height:1.7}
.divisibility-example-steps{display:grid;gap:6px;margin:7px 0 0;padding-left:22px;color:#5b6b60;font-size:10px;line-height:1.8}
.divisibility-example-steps li{padding-left:2px;overflow-wrap:anywhere}
@media(max-width:900px){.divisibility-route{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media(max-width:650px){.divisibility-route{grid-template-columns:1fr}.divisibility-rule-grid{grid-template-columns:1fr}.divisibility-rule{padding:10px}.divisibility-definition{font-size:11px}}


.lesson-method-guide{display:grid;gap:8px;margin-top:7px;color:#59675f;font-size:10px;line-height:1.75}
.lesson-method-guide p{margin:0;overflow-wrap:anywhere}
.lesson-method-guide b,.lesson-method-guide h4{color:#46624f}
.lesson-method-guide h4{margin:1px 0 -2px;font-size:10px}
.method-guide-route{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:7px;margin:0;padding:0;list-style:none}
.method-guide-route li{min-width:0;padding:8px 9px;border:1px solid #e5ebe0;border-radius:9px;background:#fffefa;overflow-wrap:anywhere}
.method-guide-route li b{display:block;margin-bottom:3px;color:#4c7658;font-size:10px}
.method-guide-route li span{display:block;color:#647168;font-size:10px;line-height:1.7;overflow-wrap:anywhere}
@media(max-width:650px){.method-guide-route{grid-template-columns:1fr}}