/* The book's pages (built by tools/book.py), on top of theme.css. The book runs on green, the logo's
   green variant (book-logo.png); the site's header keeps the cyan logo like every other page. */

.book {
    --c: var(--tint-green);
    --book-ink: #021a06;
    --book-soft: #b4ffc2;
}
.book .sheet::before, .book .sheet::after { border-color: var(--c); }
.book ::selection { background: rgba(57, 255, 90, 0.3); }
.book .label, .book .eyebrow { color: var(--c); }

/* ---------- Contents page: the cover ---------- */

.cover {
    position: relative; overflow: hidden;
    display: grid; grid-template-columns: auto 1fr; gap: clamp(1.5rem, 4vw, 3rem); align-items: center;
    padding: clamp(2.5rem, 7vw, 5rem) 0 2rem;
}
.cover .bg-icon { right: -60px; top: 10px; --size: 380px; --tint: var(--c); --alpha: 0.05; }
.cover > :not(.bg-icon) { position: relative; }
.cover-logo { --logo-size: clamp(130px, 18vw, 258px); filter: drop-shadow(0 0 12px rgba(57, 255, 90, 0.5)) drop-shadow(0 0 34px rgba(57, 255, 90, 0.22)); }
.cover .eyebrow { color: var(--c); }
.cover h1 { margin-bottom: 0.15em; }
.cover h1.glow { text-shadow: 0 0 2px rgba(4, 11, 22, 0.9), 0 0 8px rgba(4, 11, 22, 0.8), 0 0 14px rgba(57, 255, 90, 0.5), 0 0 32px rgba(57, 255, 90, 0.3); }
.cover .subtitle {
    font-family: var(--font-ui); font-weight: 600; text-transform: uppercase; letter-spacing: 0.14em;
    font-size: clamp(1.05rem, 0.9rem + 0.9vw, 1.55rem); color: var(--c); margin: 0 0 1.2rem;
}
.cover .lead { color: #cfe6d6; margin-bottom: 1.2rem; }
.cover-actions { display: flex; flex-wrap: wrap; gap: 8px; margin: 1.6rem 0 0; }
.book .btn { --c: var(--tint-green); }
.book .btn-primary { color: var(--book-ink); }
.book .btn-primary:hover { --edge: var(--book-soft); background-color: var(--book-soft); color: var(--book-ink); }
.book .btn-ghost { color: var(--text-dim); }
@media (max-width: 720px) {
    .cover { grid-template-columns: 1fr; }
    .cover-logo { --logo-size: 130px; }
}

/* ---------- Contents page: the contents ---------- */

.contents { padding-top: 2rem; }
.contents > h2 .icon { color: var(--c); }
.group { margin: 2.2rem 0 0; max-width: 980px; }
.group-head { display: flex; flex-wrap: wrap; align-items: baseline; gap: 0.2rem 0.9rem; font-size: clamp(1.15rem, 1rem + 0.7vw, 1.5rem); margin-bottom: 0.4rem; }
.group-head .label { margin: 0; }
.group-head a { color: #fff; text-decoration: none; }
.group-head a:hover { color: var(--c); }
.group-blurb { color: var(--text-dim); max-width: 75ch; margin: 0 0 1rem; }

.chapters { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--line); }
.chapters li { border-bottom: 1px solid var(--line); padding: 0.75rem 0 0.8rem; }
.chapters .ch { display: grid; grid-template-columns: 2.6rem 1fr auto; gap: 0.8rem; align-items: baseline; text-decoration: none; color: #fff; }
.chapters .n { font-family: var(--font-ui); font-weight: 600; font-size: 0.95rem; color: var(--c); }
.chapters .t { font-weight: 600; font-size: 1.08rem; line-height: 1.35; }
.chapters .m { font-family: var(--font-ui); font-size: 0.8rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--text-faint); white-space: nowrap; }
.chapters .ch:hover .t { color: var(--c); }
.chapters .secs { margin: 0.3rem 0 0 3.4rem; font-size: 0.88rem; line-height: 1.55; color: var(--text-faint); }
.chapters .secs a { color: var(--text-faint); text-decoration: none; }
.chapters .secs a:hover { color: var(--c); text-decoration: underline; }
@media (max-width: 620px) {
    .chapters .ch { grid-template-columns: 2rem 1fr; }
    .chapters .m { display: none; }
    .chapters .secs { margin-left: 2.8rem; }
}

/* ---------- Chapter pages ---------- */

/* One reading column; on wide screens the book's contents become a sticky sidebar beside it. */
.book-layout { display: grid; grid-template-columns: minmax(0, 1fr); gap: 1.4rem; max-width: 780px; padding-top: clamp(1.4rem, 4vw, 2.4rem); }
@media (min-width: 1140px) {
    .book-layout { grid-template-columns: minmax(0, 780px) 300px; gap: 0 3rem; max-width: none; }
    .book-main { grid-column: 1; grid-row: 1; }
    .book-toc {
        grid-column: 2; grid-row: 1; align-self: start;
        position: sticky; top: calc(var(--header-h) + 24px);
        max-height: calc(100vh - var(--header-h) - 48px); overflow-y: auto; overscroll-behavior: contain;
    }
}

.book-bar {
    display: flex; flex-wrap: wrap; justify-content: space-between; gap: 0.4rem 1.2rem; align-items: center;
    font-family: var(--font-ui); font-size: 0.82rem; letter-spacing: 0.1em; text-transform: uppercase; color: var(--text-faint);
    padding-bottom: 0.9rem; border-bottom: 1px solid var(--line); margin: 0 0 0.5rem;
}
.book-bar a { display: inline-flex; align-items: center; gap: 0.6rem; color: var(--c); text-decoration: none; font-weight: 600; }
.book-bar a:hover { color: #fff; }
.book-bar .logo { --logo-size: 28px; }

/* The fragment's own header: kicker and title. */
.chapter > header { padding: clamp(1.6rem, 5vw, 3rem) 0 0.6rem; }
.chapter .kicker { font-family: var(--font-ui); font-weight: 600; font-size: 0.85rem; letter-spacing: 0.16em; text-transform: uppercase; color: var(--c); margin: 0 0 0.7rem; }
.chapter h1 {
    font-size: clamp(1.8rem, 1.1rem + 2.8vw, 3rem); margin-bottom: 0.8em;
    text-shadow: 0 0 2px rgba(4, 11, 22, 0.9), 0 0 14px rgba(57, 255, 90, 0.35), 0 0 32px rgba(57, 255, 90, 0.18);
}
.chapter > header + section > h2:first-child, .chapter > header + h2 { margin-top: 0.6em; }
.part-opener > header { padding-top: clamp(3rem, 9vw, 6rem); }
.part-opener .kicker { font-size: 1rem; }
.part-opener h1 { font-size: clamp(2.1rem, 1.2rem + 3.6vw, 3.8rem); }
.part-opener > p:first-of-type { font-size: 1.2rem; color: #e1f2e6; }

.book .prose { max-width: none; }
.book .prose h2 { font-size: clamp(1.25rem, 1rem + 1vw, 1.7rem); }
.book .prose h2::before { content: ""; display: block; width: 48px; height: 3px; margin-bottom: 0.7em; background: var(--c); box-shadow: 0 0 12px var(--c); }
.book .prose h3 { color: var(--c); }
.book .prose li::marker { color: var(--c); }
.book .prose a { color: var(--c); overflow-wrap: anywhere; }
.book .prose a:hover { color: var(--book-soft); }
.book .prose em, .book .prose cite { color: #fff; }
.book .prose blockquote { border-left-color: var(--c); background: linear-gradient(90deg, rgba(57, 255, 90, 0.08), transparent); }

/* Anchor links: a "#" after each heading, shown on hover or focus (always faintly on touch screens). */
.prose .anchor {
    margin-left: 0.4em; padding: 0 0.15em;
    font-family: var(--font-ui); font-weight: 600; font-size: 0.75em;
    color: var(--c); text-decoration: none; opacity: 0; transition: opacity .15s;
}
.prose :is(h2, h3):hover .anchor, .prose .anchor:focus-visible { opacity: 0.8; }
.prose .anchor:hover { opacity: 1; }
@media (hover: none) { .prose .anchor { opacity: 0.35; } }
.prose :is(h2, h3):target { scroll-margin-top: calc(var(--header-h) + 24px); }
.prose h2:target::before { width: 96px; transition: width .4s; }

/* Title page: the foreword's epigraph cascade. */
.epigraph { margin: 0 0 3rem; padding: 0.4rem 0 0.4rem 1.2rem; border-left: 2px solid var(--c); }
.epigraph p { margin: 0.25em 0; font-family: var(--font-ui); font-size: 1.02rem; letter-spacing: 0.03em; color: var(--text-dim); }
.epigraph p:first-child { font-size: 1.2rem; color: #fff; }

.prose aside.note {
    margin: 1.6em 0; padding: 1rem 1.2rem;
    background: var(--surface-solid); border: 1px solid var(--line); box-shadow: inset 3px 0 0 var(--c);
    color: #d3e4f2; font-size: 1.02rem;
}
.prose aside.note > :last-child { margin-bottom: 0; }

.prose dl { margin: 0 0 1.4em; }
.prose dt { font-weight: 600; color: #fff; margin-top: 1em; }
.prose dd { margin: 0.2em 0 0 1.2em; padding-left: 0.9em; border-left: 1px solid var(--line-bright); }

.prose table { width: 100%; border-collapse: collapse; margin: 1.4em 0 1.8em; font-size: 0.97rem; display: block; overflow-x: auto; }
.prose th, .prose td { text-align: left; vertical-align: top; padding: 0.6rem 0.8rem; border: 1px solid var(--line); }
.prose th { font-family: var(--font-ui); font-weight: 600; letter-spacing: 0.06em; text-transform: uppercase; font-size: 0.82rem; color: var(--c); background: var(--surface-solid); }

.prose .question-spree li { color: #e8f6ec; }

/* ---------- Sidebar contents ---------- */

.book-toc { font-size: 0.9rem; }
.book-toc details { background: var(--surface); border: 1px solid var(--line); padding: 0.9rem 1.1rem 1.1rem; }
.book-toc summary { cursor: pointer; list-style: none; display: flex; align-items: center; justify-content: space-between; }
.book-toc summary::-webkit-details-marker { display: none; }
.book-toc summary::after { content: "+"; font-family: var(--font-ui); font-size: 1.2rem; color: var(--c); }
.book-toc details[open] summary::after { content: "−"; }
.book-toc summary .label { color: var(--c); margin: 0; }
@media (min-width: 1140px) { .book-toc summary { display: none; } }

.toc-book { display: flex; align-items: center; gap: 0.6rem; margin: 0.9rem 0 0.4rem; color: #fff; text-decoration: none; font-family: var(--font-ui); font-weight: 600; letter-spacing: 0.06em; text-transform: uppercase; font-size: 0.85rem; }
@media (min-width: 1140px) { .toc-book { margin-top: 0; } }
.toc-book .logo { --logo-size: 30px; }
.toc-book:hover { color: var(--c); }

.toc-group { margin: 1rem 0 0.3rem; font-family: var(--font-ui); font-weight: 600; font-size: 0.72rem; letter-spacing: 0.12em; text-transform: uppercase; color: var(--text-faint); line-height: 1.4; }
.toc-group a { color: var(--text-dim); text-decoration: none; }
.toc-group a:hover, .toc-group a[aria-current="page"] { color: var(--c); }
.book-toc ol { list-style: none; margin: 0; padding: 0; }
.book-toc ol > li > a {
    display: grid; grid-template-columns: 1.8em 1fr; padding: 0.28rem 0 0.28rem 0.5rem;
    color: var(--text-dim); text-decoration: none; line-height: 1.35; border-left: 2px solid transparent;
}
.book-toc ol > li > a:hover { color: #fff; border-left-color: var(--line-bright); }
.book-toc .n { font-family: var(--font-ui); font-weight: 600; font-size: 0.78rem; color: var(--c); padding-top: 0.12em; }
.book-toc a[aria-current="page"] { color: #fff; font-weight: 600; border-left-color: var(--c); background: linear-gradient(90deg, rgba(57, 255, 90, 0.1), transparent); }
.book-toc .toc-secs { margin: 0.1rem 0 0.4rem calc(1.8em + 0.5rem); border-left: 1px solid var(--line); }
.book-toc .toc-secs a { display: block; padding: 0.18rem 0 0.18rem 0.7rem; font-size: 0.84rem; color: var(--text-faint); text-decoration: none; line-height: 1.35; }
.book-toc .toc-secs a:hover { color: var(--c); }
.toc-itch { display: block; margin-top: 1.2rem; padding-top: 0.8rem; border-top: 1px solid var(--line); color: var(--c); text-decoration: none; font-family: var(--font-ui); font-size: 0.82rem; letter-spacing: 0.06em; text-transform: uppercase; }
.toc-itch:hover { color: #fff; }

/* ---------- End of chapter ---------- */

.offline {
    --edge: var(--line-bright);
    display: grid; grid-template-columns: auto 1fr auto; gap: 0.6rem 1.2rem; align-items: center;
    margin-top: 3.5rem; background-color: var(--surface-solid); box-shadow: inset 3px 0 0 var(--c);
}
.offline > .icon { width: 42px; height: 42px; color: var(--c); }
.offline .label { color: var(--c); margin-bottom: 0.3rem; }
.offline p:last-child { margin: 0; color: var(--text-dim); font-size: 0.97rem; }
@media (max-width: 720px) { .offline { grid-template-columns: auto 1fr; } .offline .btn { grid-column: 1 / -1; justify-self: start; } }

.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; margin-top: 1.4rem; }
.pager-link {
    display: flex; flex-direction: column; gap: 0.3rem;
    padding: 1rem 1.2rem; text-decoration: none;
    background: var(--surface-solid); border: 1px solid var(--line);
    transition: border-color .2s, box-shadow .2s;
}
.pager-link:hover { border-color: var(--c); box-shadow: 0 0 26px -10px var(--c); }
.pager-link .label { color: var(--c); margin: 0; }
.pager-title { color: #fff; font-weight: 600; line-height: 1.35; }
.pager-link.next { text-align: right; grid-column: 2; }
@media (max-width: 620px) { .pager { grid-template-columns: 1fr; } .pager-link.next { grid-column: 1; } }

.back { margin: 1.4rem 0 0; }