.breadcrumbs{margin:0 0 18px}.breadcrumbs ol{display:flex;flex-wrap:wrap;gap:6px;margin:0;padding:0;list-style:none;font-size:.8rem;font-weight:650;color:#a8bad1}.breadcrumbs li+li:before{content:"›";margin-right:6px;color:#6f86a3}.breadcrumbs a{color:#c6d6e6}.breadcrumbs a:hover{color:#fff;text-decoration:underline}.breadcrumbs [aria-current]{color:#fff}.lesson-meta{display:flex;flex-wrap:wrap;gap:8px 18px;margin-top:22px;color:#c6d6e6;font-size:.84rem;font-weight:650}.lesson-meta span{display:inline-flex;align-items:center;gap:6px}.lesson-objectives{margin:0 0 30px;padding:20px 22px;border:1px solid var(--ink-200);border-left:4px solid var(--primary-600);border-radius:6px 16px 16px 6px;background:var(--primary-50)}.lesson-objectives h2{margin:0 0 10px!important;font-size:1.02rem!important;letter-spacing:0!important}.lesson-objectives ul{margin:0!important;padding-left:20px}.lesson-objectives li{margin-bottom:6px!important;color:var(--ink-800)}.lesson-prose{max-width:760px}.lesson-prose h2{padding-top:6px;scroll-margin-top:96px}.lesson-prose h3{scroll-margin-top:96px}.lesson-prose strong{color:var(--ink-950)}.lesson-prose table{width:100%;margin:0 0 22px;border-collapse:collapse;font-size:.92rem;display:block;overflow-x:auto}.lesson-prose th,.lesson-prose td{padding:9px 12px;border:1px solid var(--ink-200);text-align:left;white-space:nowrap}.lesson-prose th{background:var(--surface-soft);color:var(--ink-800);font-weight:800}.lesson-prose .katex-display{margin:14px 0;overflow-x:auto;overflow-y:hidden;padding:2px 0}.lesson-prose .katex{font-size:1.08em}.lesson-prose .formula-box{margin:22px 0;padding:14px 20px;border:1px solid #b8d8bf;border-radius:14px;background:var(--green-50)}.lesson-prose .formula-box p{margin-bottom:8px}.lesson-prose .formula-box>:last-child{margin-bottom:0}.lesson-prose .formula-box .katex-display{margin:8px 0}.lesson-prose .worked{margin:22px 0;padding:18px 20px;border:1px solid var(--ink-200);border-radius:14px;background:var(--surface)}.lesson-prose .worked>:first-child{margin-top:0}.lesson-prose .worked>:last-child{margin-bottom:0}.lesson-prose .worked .katex-display{margin:10px 0}.lesson-prose .mistake{margin:18px 0;padding:14px 18px;border-left:4px solid var(--warning);border-radius:6px 14px 14px 6px;background:#fff7ed}.lesson-prose .mistake>:last-child{margin-bottom:0}.lesson-prose details{margin:0 0 24px;border:1px solid var(--ink-200);border-radius:14px;background:var(--surface-soft)}.lesson-prose summary{cursor:pointer;padding:14px 18px;font-weight:800;color:var(--primary-800)}.lesson-prose details[open] summary{border-bottom:1px solid var(--ink-200)}.lesson-prose details>*:not(summary){margin-left:18px;margin-right:18px}.lesson-prose details>ol,.lesson-prose details>ul{padding-left:22px;margin-left:22px}.lesson-prose details>*:last-child{margin-bottom:16px}.lesson-prose details>summary+*{margin-top:14px}.lesson-pager{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin:40px 0 0}.lesson-pager a{display:block;padding:16px 18px;border:1px solid var(--ink-200);border-radius:16px;background:var(--surface);transition:border-color .2s ease,box-shadow .2s ease}.lesson-pager a:hover{border-color:#adcbee;box-shadow:var(--shadow-md)}.lesson-pager small{display:block;color:var(--ink-500);font-size:.72rem;font-weight:800;letter-spacing:.04em;text-transform:uppercase}.lesson-pager strong{display:block;margin-top:4px;color:var(--ink-950);font-size:.95rem;line-height:1.35}.lesson-pager .next{text-align:right;grid-column:2}.lesson-pager .prev{grid-column:1}.lesson-cta{margin:36px 0 0;padding:22px 24px;border-radius:18px;background:linear-gradient(145deg,var(--primary-900),var(--primary-800));color:#fff}.lesson-cta h2{margin:0 0 8px!important;color:#fff!important;font-size:1.15rem!important}.lesson-cta p{margin:0 0 16px!important;color:#c6d6e6!important;font-size:.95rem!important}.lesson-cta .cta-row{display:flex;flex-wrap:wrap;gap:10px}.lesson-cta a{display:inline-flex;align-items:center;min-height:42px;padding:0 16px;border-radius:12px;background:#ffffff1f;color:#fff;font-size:.86rem;font-weight:800;border:1px solid rgba(255,255,255,.22)}.lesson-cta a:hover{background:#fff3}.toc-list{display:grid;gap:0;margin:0;padding:0;list-style:none}.toc-list a{display:block;padding:8px 0;border-top:1px solid var(--ink-200);color:var(--ink-700);font-size:.84rem;font-weight:650;line-height:1.4}.toc-list li:first-child a{border-top:0}.toc-list a:hover{color:var(--primary-700)}.side-current{display:block;padding:10px 0;border-top:1px solid var(--ink-200);color:var(--primary-700);font-size:.85rem;font-weight:800}.strand-heading{margin:34px 0 14px;font-size:1.15rem;color:var(--ink-900)}.strand-heading:first-child{margin-top:0}.hub-intro{max-width:780px;margin-bottom:38px}.hub-intro p{margin-bottom:16px;color:var(--ink-700);font-size:1.03rem;line-height:1.75}.hub-steps{display:grid;grid-template-columns:repeat(4,1fr);gap:14px;margin-top:8px;padding:0;list-style:none;counter-reset:step}.hub-steps li{counter-increment:step;padding:18px;border:1px solid var(--ink-200);border-radius:16px;background:var(--surface);font-size:.9rem;color:var(--ink-700)}.hub-steps li:before{content:counter(step);display:grid;place-items:center;width:30px;height:30px;margin-bottom:10px;border-radius:50%;background:var(--primary-700);color:#fff;font-weight:800;font-size:.85rem}.hub-steps strong{display:block;margin-bottom:4px;color:var(--ink-950)}.lesson-list-card{text-decoration:none}.level-block{margin-bottom:44px}.level-block>h2{margin-bottom:6px}.level-block>p{margin-bottom:20px;color:var(--ink-600)}@media(max-width:1080px){.hub-steps{grid-template-columns:repeat(2,1fr)}}@media(max-width:640px){.hub-steps,.lesson-pager{grid-template-columns:1fr}.lesson-pager .next,.lesson-pager .prev{grid-column:auto;text-align:left}}.lesson-prose{min-width:0}.lesson-prose figure{margin:22px 0;overflow-x:auto}.lesson-prose figure>svg{max-width:100%;height:auto}@media(max-width:1080px){.article-body-layout{grid-template-columns:minmax(0,1fr)}}