/* Scoped to the public shell; colors follow the existing lesson theme. */
.track-b-header,.track-b-breadcrumb,.track-b-footer{color:var(--ink,#1F1A16);font-family:Assistant,system-ui,sans-serif}
.track-b-header a,.track-b-breadcrumb a,.track-b-footer a{color:inherit}
.track-b-header{--card-shadow:0 1px 0 rgb(31 26 22 / .04),0 12px 32px -12px rgb(82 52 20 / .18);position:sticky;top:0;z-index:20;line-height:1.7;background:color-mix(in oklab,var(--ground,#FAF6F0) 88%,transparent);-webkit-backdrop-filter:blur(14px);backdrop-filter:blur(14px);border-bottom:1px solid var(--line,#E6DDD1)}
.track-b-header .header-inner{max-width:1360px;margin:auto;display:flex;align-items:center;gap:28px;min-height:68px;padding:0 32px}
.track-b-header .wordmark{display:flex;align-items:center;gap:0;font:800 22px/1.2 var(--f-body,Assistant,system-ui,sans-serif);letter-spacing:-.02em;direction:ltr;text-decoration:none;color:var(--ink,#1F1A16);white-space:nowrap}
.track-b-header .wordmark span{color:inherit;background:none;padding:0;border-radius:0}
.track-b-header .wordmark .wordmark-dot{order:-1;display:inline-block;width:22px;height:14px;border-radius:3px 8px 4px 7px;background:var(--mark,#FFD15C);transform:rotate(-4deg);margin:0 0 0 10px}
.track-b-header .header-inner>nav{display:flex;position:static;inset:auto;align-items:center;gap:2px;flex:1;min-width:0;width:auto;height:auto;margin:0;padding:0;border:0;background:transparent;color:inherit;overflow:visible}
.track-b-header .header-inner>nav>a{display:flex;align-items:center;min-height:44px;font-size:16px;font-weight:500;color:var(--ink-2,#544B44);text-decoration:none;padding:0 12px;border-radius:var(--r-pill,999px)}
.track-b-header .header-inner>nav>a:hover{color:var(--ink,#1F1A16);background:var(--surface-2,#F2ECE3)}
.track-b-header .nav-end{margin-inline-start:auto;display:flex;align-items:center;gap:10px}
.track-b-header button,.track-b-header .button{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:44px;min-width:44px;border:1px solid var(--ink,#1F1A16);border-radius:var(--r-pill,999px);background:var(--ink,#1F1A16);color:var(--ground,#FAF6F0);margin:0;padding:8px 24px;font:inherit;font-weight:650;line-height:1.4;position:relative;overflow:hidden;isolation:isolate;cursor:pointer;text-decoration:none}
.track-b-header button::before,.track-b-header .button::before{content:"";position:absolute;inset:0;background:var(--mark,#FFD15C);z-index:-1;clip-path:inset(0 0 0 100%);transition:clip-path .45s var(--ease,ease)}
.track-b-header button:hover,.track-b-header .button:hover{color:var(--mark-ink,#1F1A16);text-decoration:none}
.track-b-header button:hover::before,.track-b-header .button:hover::before{clip-path:inset(0)}
.track-b-header .secondary{background:transparent;color:var(--ink,#1F1A16);border-color:var(--line-2,#8C7F72)}
.track-b-header .secondary:hover{border-color:var(--ink,#1F1A16)}
.track-b-header :focus-visible{outline:3px solid var(--ink,#1F1A16);outline-offset:3px;border-radius:4px}
.track-b-header .menu-toggle{display:none}
/* The existing runtime keeps the button's accessible text and pressed state. */
.track-b-header .header-inner .theme-toggle{--track-b-theme-mask:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='black' stroke-width='1.5' stroke-linecap='round'%3E%3Cpath d='M21 12.8A9 9 0 1 1 11.2 3a7 7 0 0 0 9.8 9.8Z'/%3E%3C/svg%3E");display:inline-flex;align-items:center;justify-content:center;flex-shrink:0;width:36px;height:36px;padding:0;font-size:0}
.track-b-header .theme-toggle::after{content:"";display:block;width:18px;height:18px;background:currentColor;-webkit-mask:var(--track-b-theme-mask) center/contain no-repeat;mask:var(--track-b-theme-mask) center/contain no-repeat}
.track-b-header .theme-toggle[aria-pressed=true]{--track-b-theme-mask:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='black' stroke-width='1.5' stroke-linecap='round'%3E%3Ccircle cx='12' cy='12' r='4'/%3E%3Cpath d='M12 2v2M12 20v2M4.9 4.9l1.4 1.4M17.7 17.7l1.4 1.4M2 12h2M20 12h2M4.9 19.1l1.4-1.4M17.7 6.3l1.4-1.4'/%3E%3C/svg%3E")}
.track-b-breadcrumb{max-width:920px;margin:auto;padding:48px 24px 0;font-size:14px;line-height:1.7;color:var(--ink-2,#544B44)}
.track-b-breadcrumb ol{display:flex;flex-wrap:wrap;gap:4px 6px;list-style:none;margin:0;padding:0}
.track-b-breadcrumb li+li::before{content:"/";margin-inline-end:6px}
.track-b-footer nav a{display:inline-flex;align-items:center;min-height:44px}
.track-b-footer{max-width:820px;margin:auto;padding:24px;border-top:1px solid var(--line,#E6DDD1);font-size:15px}
.track-b-footer nav{display:flex;flex-wrap:wrap;gap:4px 16px;margin-top:12px}
@media(max-width:767px){.track-b-header .header-inner{padding:0 16px;gap:12px}.track-b-header .wordmark{font-size:21px}.track-b-header .menu-toggle{display:inline-flex;margin-inline-start:auto;padding:0 16px;min-height:44px}.track-b-header .header-inner>nav{display:none;position:fixed;top:68px;inset-inline:0;inset-block-end:auto;width:auto;background:var(--surface,#FFFFFF);border-bottom:1px solid var(--line,#E6DDD1);padding:12px 16px;flex-direction:column;align-items:stretch;gap:8px;box-shadow:var(--card-shadow)}.track-b-header .header-inner>nav:popover-open{display:flex}.track-b-header .header-inner>nav>a{min-height:48px;padding:0 12px}.track-b-header .header-inner nav a,.track-b-header .header-inner nav button{font-size:16px}.track-b-header .nav-end{margin:0;justify-content:space-between;padding-top:8px}.track-b-breadcrumb{padding:28px 16px 0}}
/* A menu left open during resize keeps a working fallback in older engines. */
@media(min-width:768px){.track-b-header .header-inner>nav:popover-open{position:fixed;top:68px;inset-inline:0;width:auto;background:var(--surface,#FFFFFF);border-bottom:1px solid var(--line,#E6DDD1);padding:12px 32px}}
/* Restore the exact flex slot while an open native popover is in the top layer. */
@supports(anchor-name:--track-b-nav-slot){@media(min-width:768px){.track-b-header .header-inner:has(>nav:popover-open)::after{content:"";flex:1;height:44px;anchor-name:--track-b-nav-slot}.track-b-header .header-inner>nav:popover-open{position-anchor:--track-b-nav-slot;top:anchor(top);left:anchor(left);right:auto;width:anchor-size(width);height:anchor-size(height);padding:0;border:0;background:transparent}}}
@media(max-width:600px){.track-b-footer{padding-inline:16px}}

/* Course indexes follow the site's course overview layout. */
.track-b-course-overview{--accent:var(--ink);max-width:920px;margin:0 auto;padding:48px 24px 80px;overflow-wrap:anywhere;line-height:1.7;font-variant-numeric:tabular-nums}
.track-b-breadcrumb+.track-b-course-overview{padding-top:32px}
.track-b-course-overview .course-overview-header{padding-bottom:36px;border-bottom:1px solid var(--line)}
.track-b-course-overview .eyebrow{font-size:14px;color:var(--ink-2);font-weight:650;margin-bottom:12px}
.track-b-course-overview .course-overview-header h1{font-size:clamp(34px,4.4vw,56px);font-weight:300;letter-spacing:-.025em;line-height:1.2;margin:12px 0 24px}
.track-b-course-overview .course-overview-lead{font-size:21px;line-height:1.75;color:var(--ink-2)}
.track-b-course-overview .course-overview-meta{font-size:15px;color:var(--ink-2)}
.track-b-course-overview .actions{display:flex;gap:12px;align-items:center;flex-wrap:wrap}
.track-b-course-overview .course-overview-section{margin-top:40px}
.track-b-course-overview .course-overview-section>h2{font-size:28px;font-weight:650;margin:0 0 16px}
.track-b-course-overview .course-overview-section>p{font-size:18px;line-height:1.75}
.track-b-course-overview .course-overview-modules{list-style:none;counter-reset:track-b-module;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px;padding:0;margin:24px 0}
.track-b-course-overview .course-overview-modules>li{counter-increment:track-b-module;min-width:0;background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:20px;margin:0}
.track-b-course-overview .course-overview-modules>li::before{content:counter(track-b-module,decimal-leading-zero);font-size:14px;color:var(--accent)}
.track-b-course-overview .course-overview-modules h3{font-size:19px;line-height:1.5;margin:8px 0}
.track-b-course-overview .course-overview-modules>li>p{margin:0;font-size:15px;color:var(--ink-2)}
.track-b-course-overview .course-overview-modules>li>.course-overview-module-description{margin-top:8px;font-size:14px;line-height:1.6;color:var(--ink-3)}
.track-b-course-overview .track-b-lesson-group{margin-top:24px}
.track-b-course-overview .track-b-lesson-group>h3{font-size:19px;font-weight:650;line-height:1.5;margin:0 0 8px}
.track-b-course-overview .track-b-lesson-group>h3>a{display:inline-flex;align-items:center;min-height:44px}
.track-b-course-overview .track-b-lesson-navigation .toc{margin:0;font-size:16px}
.track-b-course-overview .track-b-lesson-navigation .toc a{position:relative;padding:8px 0;padding-inline-start:36px;line-height:1.55;color:var(--ink-2)}
.track-b-course-overview .track-b-lesson-navigation .toc a::before{position:absolute;inset-inline-start:0;min-width:24px;margin:0;font-variant-numeric:tabular-nums}
.track-b-course-overview .track-b-lesson-navigation .toc li:last-child a{border-bottom:0}
:root[data-theme=dark] .track-b-course-overview{--accent:var(--mark)}
:root[data-theme=dark] .track-b-header{--card-shadow:0 0 0 1px rgb(255 220 160 / .05),0 20px 48px -20px rgb(0 0 0 / .7)}
@media(prefers-color-scheme:dark){:root:not([data-theme=light]) .track-b-course-overview{--accent:var(--mark)}}
@media(prefers-color-scheme:dark){:root:not([data-theme=light]) .track-b-header{--card-shadow:0 0 0 1px rgb(255 220 160 / .05),0 20px 48px -20px rgb(0 0 0 / .7)}}
@media(max-width:767px){.track-b-course-overview{padding:28px 16px 64px}.track-b-breadcrumb+.track-b-course-overview{padding-top:24px}.track-b-course-overview .course-overview-lead{font-size:19px}.track-b-course-overview .course-overview-modules{grid-template-columns:1fr}.track-b-course-overview .actions{align-items:stretch;flex-direction:column}.track-b-course-overview .actions .button{justify-content:center;text-align:center}}