/* AP Chemistry identity: a blue course color, next to Chemistry I green and Chemistry II plum */
:root{--course:#1f5aa6;--course-soft:#e8f0fb;--on-course:#fff}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){--course:#8db7f2;--course-soft:#1b2638;--on-course:#0f1724}}
:root[data-theme="dark"]{--course:#8db7f2;--course-soft:#1b2638;--on-course:#0f1724}

/* header: course pill and a plum rule under the bar */
.bar{border-bottom:3px solid var(--course)}
.brand-sub.course-pill{border:0;padding:.28rem .7rem .28rem .3rem;border-radius:999px;background:var(--course);color:var(--on-course);font-weight:700;font-size:.85rem;display:inline-flex;align-items:center;gap:.45rem;letter-spacing:.01em}
.course-pill .cn{display:inline-grid;place-items:center;min-width:1.7rem;height:1.7rem;border-radius:999px;background:var(--on-course);color:var(--course);font-family:var(--display);font-weight:700;font-size:.95rem;letter-spacing:.02em}
@media (max-width:560px){.brand-sub.course-pill{font-size:.78rem;padding:.22rem .55rem .22rem .25rem}.course-pill .cn{min-width:1.45rem;height:1.45rem;font-size:.82rem}}

/* hero: the course name and the closing line carry the course color */
.book-line .bl-course{color:var(--course)}
.f-h1 em{color:var(--course)}
.course-switch{margin:.9rem 0 0;display:flex;flex-wrap:wrap;gap:.35rem .8rem;align-items:center;font-size:.95rem;color:var(--muted)}
.course-switch .cs-now{display:inline-flex;align-items:center;gap:.4rem;background:var(--course-soft);color:var(--course);font-weight:700;border-radius:999px;padding:.2rem .7rem}
.course-switch a{color:var(--ink);font-weight:600;text-underline-offset:3px}

/* lesson and chapter pages: course label and plum numbers */
.screen-top .tn{background:var(--course)}
.crumbs .crumb-course{font-weight:700;color:var(--course)}
.chapters .num,.toc-list .num{color:var(--course)}
/* Course title + Chemistry I / Chemistry II toggle (same on both course pages) */
:root{--c1:#1f6f5c;--c2:#6b3fa0}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){--c1:#6fd0b4;--c2:#c5a8ee}}
:root[data-theme="dark"]{--c1:#6fd0b4;--c2:#c5a8ee}
.f-hero .book-line.bl-small{display:block;margin:0;font-size:clamp(.95rem,1.9vw,1.12rem);letter-spacing:.16em;color:var(--course);font-weight:800;text-transform:uppercase}
@media (max-width:480px){.f-hero .book-line.bl-small{font-size:.8rem;letter-spacing:.06em}}
.f-hero .f-h1.course-h1{margin-top:.35rem;white-space:nowrap;font-size:clamp(2.1rem,4.4vw,3.2rem);line-height:1.05;font-weight:700;color:var(--ink)}
.f-hero .course-h1 .ch-num{color:var(--course)}
.course-toggle{display:grid;grid-template-columns:1fr 1fr;gap:.5rem;max-width:30rem;margin-top:1.1rem}
.course-toggle .ct{--cc:var(--c1);display:grid;gap:.05rem;padding:.65rem .95rem;border-radius:14px;border:2px solid color-mix(in srgb,var(--cc) 35%,var(--line));background:var(--surface);color:var(--ink);text-decoration:none;line-height:1.25;transition:border-color .15s,transform .15s}
.course-toggle .ct2{--cc:var(--c2)}
.course-toggle .ct b{font-family:var(--display);font-size:1.12rem;color:var(--cc)}
.course-toggle .ct span{font-size:.85rem;color:var(--muted)}
.course-toggle .ct:hover{border-color:var(--cc);transform:translateY(-1px)}
.course-toggle .ct[aria-current="page"]{background:var(--cc);border-color:var(--cc);cursor:default;transform:none}
.course-toggle .ct[aria-current="page"] b,.course-toggle .ct[aria-current="page"] span{color:var(--on-course,#fff)}
.course-toggle .ct[aria-current="page"] b::before{content:"✓ ";font-family:var(--body);font-size:.95rem}
.course-toggle .ct:not([aria-current]) span::after{content:" →"}
.f-hero .f-tagline{margin:1.1rem 0 0;font-family:var(--display);font-weight:600;font-size:clamp(1.25rem,2.6vw,1.6rem);line-height:1.3;color:var(--ink)}
.f-hero .f-tagline em{font-style:normal;color:var(--course)}
.f-hero .f-tagline+.pro-badge{margin-top:.9rem}
@media (max-width:560px){.course-toggle{max-width:none}.course-toggle .ct{padding:.55rem .7rem}.course-toggle .ct b{font-size:1.02rem}.f-hero .f-h1.course-h1{font-size:clamp(1.75rem,8.6vw,2.2rem)}}

/* AP Chemistry: the third course (this page) */
:root{--c3:#1f5aa6}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){--c3:#8db7f2}}
:root[data-theme="dark"]{--c3:#8db7f2}
.course-toggle{grid-template-columns:1fr 1fr 1fr;max-width:44rem}
.course-toggle .ct3{--cc:var(--c3)}
@media (max-width:560px){.course-toggle{grid-template-columns:1fr 1fr;grid-auto-rows:1fr}}
.course-h1 .reg{font-size:.4em;font-weight:600;vertical-align:baseline;position:relative;top:-1.1em;margin-left:.03em;font-family:var(--body)}
footer .foot-note{flex-basis:100%;font-size:.78rem;color:var(--muted)}

/* Free ticks: green pills, easy to spot */
#view-home .f-ticks,.home .f-ticks{gap:.5rem;margin-top:1.1rem;font-size:1rem}
#view-home .f-ticks li,.home .f-ticks li{display:inline-flex;align-items:center;gap:.35rem;padding:.4rem .85rem;border-radius:999px;background:var(--green-soft);color:var(--green);font-weight:700;border:1px solid color-mix(in srgb,var(--green) 30%,transparent)}
#view-home .f-ticks li::before,.home .f-ticks li::before{content:"✓";font-weight:800}
@media (max-width:560px){#view-home .f-ticks,.home .f-ticks{font-size:.92rem;gap:.4rem}#view-home .f-ticks li,.home .f-ticks li{padding:.32rem .7rem}}