/* ==========================================================================
   Fizik Akademisi Dersler — kütüphane ve kitap sayfaları YKS Fizik'in "defter" dilinde,
   bölüm sayfası bir ders kitabı gibi: geniş satır aralığı, serif metin, numaralı denklemler.
   ========================================================================== */
body.fa-ders-focus {
  --d-ink: #17191d; --d-ink2: #3a3f48; --d-mut: #6b6f78; --d-rule: #dedad0; --d-paper: #fffdf8; --d-bg: #f8f4ea;
  --d-acc: #2f5d8a; --d-acc-bg: #e8f0f8; --d-def: #2f5d8a; --d-def-bg: #eef4fa; --d-law: #7a3db8; --d-law-bg: #f4eefb;
  --d-ex: #b45309; --d-ex-bg: #fdf5e9; --d-pr: #1f6f4a; --d-pr-bg: #edf7f1; --d-warn: #b3261e; --d-warn-bg: #fbecea;
  --d-hl: #ffd84d; --d-serif: "Source Serif 4", Georgia, "Times New Roman", serif; --d-sans: "Libre Franklin", "Helvetica Neue", Arial, sans-serif;
  --d-nb: "Bricolage Grotesque", "Libre Franklin", system-ui, sans-serif; --d-border: 2.5px solid var(--d-ink); --d-shadow: 4px 4px 0 var(--d-ink);
  margin: 0; color: var(--d-ink); background-color: #fbf7ee;
  background-image: linear-gradient(#e3eaf5 1px, transparent 1px), linear-gradient(90deg, #e3eaf5 1px, transparent 1px), linear-gradient(#c9d6ec 1px, transparent 1px), linear-gradient(90deg, #c9d6ec 1px, transparent 1px);
  background-size: 12px 12px, 12px 12px, 60px 60px, 60px 60px;
}
body.fa-ders-v-chapter { background: var(--d-bg); }
.fa-ders-focus *, .fa-ders-focus *::before, .fa-ders-focus *::after { box-sizing: border-box; }
.fa-ders-focus :focus-visible { outline: 3px solid var(--d-acc); outline-offset: 2px; }
.d-wrap { max-width: 1200px; margin: 0 auto; padding: 0 20px; }
.fa-ders-focus .logo { color: var(--d-ink); text-decoration: none; }

/* üst çubuk ve alt bilgi (YKS ile aynı) */
.d-top { background: #fbf7ee; border-bottom: var(--d-border); position: sticky; top: env(safe-area-inset-top, 0px); z-index: 50; }
.d-top .d-wrap { display: flex; align-items: center; justify-content: space-between; gap: 12px; min-height: 58px; }
.d-top-brand { display: flex; align-items: baseline; gap: 10px; min-width: 0; }
.d-top-brand .logo { font-size: 30px; line-height: 1; white-space: nowrap; }
.d-top-brand b, .d-top-name { font: 800 20px/1 var(--d-nb); letter-spacing: -.03em; color: var(--d-ink); text-decoration: none; white-space: nowrap; }
.d-top-name:hover { text-decoration: underline; text-underline-offset: 4px; }
.d-top-back { flex: none; font: 800 12px/1 var(--d-nb); letter-spacing: .06em; text-transform: uppercase; color: var(--d-ink); text-decoration: none; background: #fff; border: var(--d-border); border-radius: 10px; padding: 9px 14px; box-shadow: 3px 3px 0 var(--d-ink); transition: transform .12s, box-shadow .12s; }
.d-top-back:hover { transform: translate(-1px, -1px); box-shadow: 4px 4px 0 var(--d-ink); }
.d-foot { margin-top: 56px; border-top: var(--d-border); background: #fbf7ee; }
.d-foot .d-wrap { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 12px; padding-block: 20px; }
.d-foot .logo { font-size: 24px; }
.d-foot span { font: 400 13px var(--d-sans); color: #6b665c; }
.d-foot span a { color: var(--d-ink); }

/* ortak */
.d-kicker { display: inline-block; margin: 0 0 14px; padding: 4px 10px; background: var(--d-ink); color: #fff; font: 800 12px/1.2 var(--d-nb); letter-spacing: .08em; text-transform: uppercase; border-radius: 6px; }
.d-hl { background: linear-gradient(transparent 60%, var(--d-hl) 60%, var(--d-hl) 92%, transparent 92%); }
.d-lede { font: 400 19px/1.55 var(--d-sans); color: var(--d-ink2); max-width: 46em; margin: 16px 0 0; }
.d-btn { display: inline-flex; align-items: center; gap: 8px; padding: 12px 20px; border: var(--d-border); border-radius: 12px; background: #fff; color: var(--d-ink); font: 800 15px/1 var(--d-nb); text-decoration: none; box-shadow: var(--d-shadow); transition: transform .12s, box-shadow .12s; }
.d-btn:hover { transform: translate(-1px, -1px); box-shadow: 5px 5px 0 var(--d-ink); }
.d-btn-dark { background: var(--d-ink); color: #fff; }
.d-crumbs { font: 600 13px/1.4 var(--d-sans); color: var(--d-mut); margin-bottom: 18px; }
.d-crumbs a { color: var(--d-mut); text-decoration: none; }
.d-crumbs a:hover { color: var(--d-ink); text-decoration: underline; }

/* kütüphane */
.d-hero { padding: 56px 0 28px; }
.d-hero h1 { font: 800 clamp(38px, 6vw, 68px)/1.02 var(--d-nb); letter-spacing: -.035em; margin: 0; max-width: 15em; text-wrap: balance; }
.d-facts { display: flex; flex-wrap: wrap; gap: 0; margin: 28px 0 0; padding: 0; }
.d-facts div { padding: 4px 26px 4px 0; margin-right: 26px; border-right: 2px solid var(--d-ink); }
.d-facts div:last-child { border: 0; }
.d-facts dt { font: 600 12px var(--d-sans); color: var(--d-mut); }
.d-facts dd { margin: 0; font: 800 34px/1.1 var(--d-nb); letter-spacing: -.03em; }
.d-year { margin-top: 38px; }
.d-year-h { font: 800 13px var(--d-nb); letter-spacing: .14em; text-transform: uppercase; margin: 0 0 16px; }
.d-year-h span { background: var(--d-hl); padding: 4px 10px; }
.d-shelf { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 18px; }
.d-book { position: relative; display: flex; min-height: 168px; background: var(--d-paper); border: var(--d-border); border-radius: 14px; box-shadow: var(--d-shadow); color: inherit; text-decoration: none; overflow: hidden; transition: transform .12s, box-shadow .12s; }
a.d-book:hover { transform: translate(-2px, -2px); box-shadow: 6px 6px 0 var(--d-ink); }
.d-book-spine { flex: none; width: 18px; border-right: var(--d-border); background: var(--spine, #c9d6ec); }
.d-book-y1 { --spine: #ffd84d; } .d-book-y2 { --spine: #8fb8e8; } .d-book-y3 { --spine: #c3a6ff; } .d-book-y4 { --spine: #9ad7b3; }
.d-book-in { display: flex; flex-direction: column; gap: 8px; padding: 16px 18px; min-width: 0; }
.d-book-t { font: 800 20px/1.15 var(--d-nb); letter-spacing: -.02em; }
.d-book-d { font: 400 14px/1.45 var(--d-sans); color: var(--d-ink2); }
.d-book-m { margin-top: auto; font: 600 13px var(--d-sans); color: var(--d-acc); }
.d-book-soon { box-shadow: none; border-style: dashed; border-color: #9a978f; background: rgba(255,253,248,.7); }
.d-book-soon .d-book-spine { background: repeating-linear-gradient(45deg, #ece7da 0 6px, #f6f2e8 6px 12px); border-right: 2.5px dashed #9a978f; }
.d-book-soon .d-book-t { color: #55524b; }
.d-book-soon .d-book-d { color: #77736a; }
.d-book-soon .d-book-m { color: #8a867d; font-style: italic; }
.d-note { margin-top: 32px; font: 400 14px var(--d-sans); color: var(--d-mut); }

/* kitap sayfası */
.d-hero-book { padding-top: 32px; }
.d-cover { display: grid; grid-template-columns: 220px minmax(0, 1fr); gap: 40px; align-items: center; }
.d-cover-art { aspect-ratio: 3 / 4; max-width: 100%; border: var(--d-border); border-radius: 10px 16px 16px 10px; box-shadow: 8px 8px 0 var(--d-ink); background: #24405f; color: #fff; display: flex; flex-direction: column; justify-content: space-between; padding: 22px 18px 18px 30px; position: relative; overflow: hidden; }
.d-cover-art::before { content: ""; position: absolute; left: 12px; top: 0; bottom: 0; width: 3px; background: rgba(255,255,255,.35); }
.d-cover-art::after { content: ""; position: absolute; right: -40px; bottom: -40px; width: 170px; height: 170px; border-radius: 50%; border: 2px solid rgba(255,216,77,.55); box-shadow: 0 0 0 22px rgba(255,216,77,.12), 0 0 0 46px rgba(255,216,77,.07); }
.d-cover-art span { font: 800 28px/1.05 var(--d-nb); letter-spacing: -.02em; position: relative; }
.d-cover-art i { font: 400 13px var(--d-serif); opacity: .85; position: relative; }
.d-cover-txt h1 { font: 800 clamp(36px, 5vw, 56px)/1.02 var(--d-nb); letter-spacing: -.03em; margin: 0; }
.d-prereq { font: 400 15px/1.5 var(--d-sans); color: var(--d-ink2); margin: 14px 0 22px; }
.d-course { display: grid; grid-template-columns: minmax(0, 1fr); gap: 28px; max-width: 900px; }
.d-course-intro { background: var(--d-paper); border: var(--d-border); border-radius: 14px; padding: 22px 26px; box-shadow: var(--d-shadow); }
.d-toc-book h2 { font: 800 28px var(--d-nb); letter-spacing: -.02em; margin: 0 0 14px; }
.d-toc-book > ol { list-style: none; margin: 0; padding: 0; display: grid; gap: 12px; }
.d-ch > a, .d-ch > div { display: grid; grid-template-columns: 54px minmax(0, 1fr); gap: 14px; align-items: start; padding: 16px 18px; background: var(--d-paper); border: var(--d-border); border-radius: 14px; color: inherit; text-decoration: none; box-shadow: var(--d-shadow); transition: transform .12s, box-shadow .12s; }
.d-ch > a:hover { transform: translate(-2px, -2px); box-shadow: 6px 6px 0 var(--d-ink); }
.d-ch-n { font: 800 34px/1 var(--d-nb); letter-spacing: -.04em; color: var(--d-acc); }
.d-ch-b { display: flex; flex-direction: column; gap: 4px; }
.d-ch-b b { font: 800 20px/1.2 var(--d-nb); letter-spacing: -.015em; }
.d-ch-b span { font: 400 15px/1.5 var(--d-sans); color: var(--d-ink2); }
.d-ch-b em { font: 600 13px var(--d-sans); color: var(--d-mut); font-style: normal; margin-top: 4px; }
.d-ch-sec { list-style: none; margin: 8px 0 4px 72px; padding: 0; columns: 2; column-gap: 24px; }
.d-ch-sec a { display: block; padding: 3px 0; font: 400 14px/1.4 var(--d-sans); color: var(--d-ink2); text-decoration: none; break-inside: avoid; }
.d-ch-sec a span { font-weight: 700; color: var(--d-mut); margin-right: 4px; }
.d-ch-sec a:hover { color: var(--d-acc); text-decoration: underline; }
.d-ch-soon > div { box-shadow: none; border-style: dashed; border-color: #a8a49b; background: rgba(255,253,248,.65); }
.d-ch-soon .d-ch-n { color: #a8a49b; }
.d-ch-soon .d-ch-b b { color: #5f5b53; }

/* ---------- bölüm (kitap sayfası) ---------- */
.d-reader { display: grid; grid-template-columns: 250px minmax(0, 1fr); gap: 48px; padding-top: 28px; }
.d-reader > .d-chapter { grid-column: -2 / -1; min-width: 0; }
.d-side-in { position: sticky; top: calc(env(safe-area-inset-top, 0px) + 78px); max-height: calc(100vh - 100px); overflow: auto; padding-bottom: 12px; }
.d-side-book { display: block; font: 800 16px/1.2 var(--d-nb); color: var(--d-ink); text-decoration: none; }
.d-side-book:hover { text-decoration: underline; }
.d-side-k { font: 700 11px var(--d-sans); letter-spacing: .12em; text-transform: uppercase; color: var(--d-mut); margin: 6px 0 10px; }
.d-side ol { list-style: none; margin: 0; padding: 0; border-left: 2px solid var(--d-rule); }
.d-side li a { display: block; padding: 6px 10px; margin-left: -2px; border-left: 2px solid transparent; font: 500 13.5px/1.35 var(--d-sans); color: var(--d-ink2); text-decoration: none; }
.d-side li a span { display: inline-block; min-width: 30px; font-weight: 700; color: var(--d-mut); }
.d-side li a:hover, .d-side li a.on { color: var(--d-ink); border-left-color: var(--d-ink); }
.d-side li a.on span { color: var(--d-acc); }
.d-progress { height: 4px; background: var(--d-rule); border-radius: 2px; margin-top: 14px; overflow: hidden; }
.d-progress i { display: block; height: 100%; width: 0; background: var(--d-acc); transition: width .15s; }

.d-chapter { max-width: 780px; }
.d-ch-head { border-bottom: 1px solid var(--d-rule); padding-bottom: 22px; margin-bottom: 26px; }
.d-ch-k { font: 800 13px var(--d-nb); letter-spacing: .14em; text-transform: uppercase; color: var(--d-acc); margin: 0 0 6px; }
.d-ch-head h1 { font: 700 clamp(34px, 5vw, 52px)/1.06 var(--d-serif); letter-spacing: -.02em; margin: 0; text-wrap: balance; }
.d-dek { font: 400 20px/1.55 var(--d-serif); color: var(--d-ink2); margin: 14px 0 0; }
.d-ch-meta { display: flex; flex-wrap: wrap; gap: 8px 18px; margin: 16px 0 0; font: 600 13px var(--d-sans); color: var(--d-mut); }
.d-ch-meta span + span::before { content: "·"; margin-right: 18px; color: var(--d-rule); }
.d-goals { background: var(--d-paper); border: 1px solid var(--d-rule); border-top: 4px solid var(--d-ink); padding: 16px 22px 6px; margin: 0 0 30px; }
.d-goals-k { font: 700 11px var(--d-sans); letter-spacing: .12em; text-transform: uppercase; color: var(--d-mut); margin-bottom: 6px; }
.d-goals ul { margin: 0; padding-left: 20px; font: 400 16.5px/1.6 var(--d-serif); }
.d-goals li { margin-bottom: 6px; }

.d-prose { font: 400 18.5px/1.72 var(--d-serif); color: var(--d-ink); font-feature-settings: "kern", "liga", "onum"; hyphens: auto; }
.d-prose p { margin: 0 0 1.05em; }
.d-prose strong { font-weight: 600; }
.d-prose a { color: var(--d-acc); }
.d-prose ul, .d-prose ol { margin: 0 0 1.1em; padding-left: 1.4em; }
.d-prose li { margin-bottom: .35em; }
.d-h2 { font: 700 29px/1.2 var(--d-serif); letter-spacing: -.012em; margin: 2.1em 0 .7em; scroll-margin-top: 84px; display: flex; gap: .55em; align-items: baseline; text-wrap: balance; }
.d-h2-n { font: 800 .72em/1 var(--d-nb); color: var(--d-acc); letter-spacing: -.01em; flex: none; }
.d-h2-u { border-top: 3px double var(--d-ink); padding-top: .9em; }
.d-h3 { font: 700 21px/1.3 var(--d-serif); margin: 1.6em 0 .5em; font-style: italic; }
.d-eq { display: grid; grid-template-columns: minmax(0, 1fr) auto; align-items: center; gap: 14px; margin: 1.1em 0 1.25em; scroll-margin-top: 90px; }
.d-eq-m { overflow-x: auto; overflow-y: hidden; padding: 2px 0; }
.d-eq-m .katex-display { margin: 0; }
.d-eq-n { font: 400 17px var(--d-serif); color: var(--d-ink2); white-space: nowrap; }
.d-eq:target { background: #fff6d6; border-radius: 6px; }
.d-ref { color: var(--d-acc); text-decoration: none; border-bottom: 1px dotted currentColor; white-space: nowrap; }
.d-ref-x { color: var(--d-warn); }
.d-fig { margin: 1.6em 0; text-align: center; scroll-margin-top: 90px; }
.d-fig img { max-width: 100%; height: auto; background: #fff; border: 1px solid var(--d-rule); border-radius: 8px; }
.d-fig figcaption { font: 400 15px/1.5 var(--d-sans); color: var(--d-ink2); margin: 10px auto 0; max-width: 40em; text-align: left; }
.d-fig figcaption b { color: var(--d-ink); }
.d-table { overflow-x: auto; margin: 1.2em 0 1.5em; }
.d-table table { border-collapse: collapse; width: 100%; font: 400 15.5px/1.45 var(--d-sans); }
.d-table th, .d-table td { border-bottom: 1px solid var(--d-rule); padding: 8px 10px; text-align: left; vertical-align: top; }
.d-table th { border-bottom: 2px solid var(--d-ink); font-weight: 700; }

/* kod */
.d-code { position: relative; margin: 1.2em 0 1.4em; padding: 16px 18px; background: #1b1e24; color: #e9e6df; border-radius: 10px; overflow-x: auto; font: 400 14px/1.6 ui-monospace, "SF Mono", Menlo, Consolas, monospace; tab-size: 4; }
.d-code[data-lang]::before { content: attr(data-lang); position: absolute; top: 6px; right: 10px; font: 700 10.5px var(--d-sans); letter-spacing: .1em; text-transform: uppercase; color: #8b8f99; }
.d-code code { font: inherit; white-space: pre; }

/* kutular */
.d-box { margin: 1.5em 0; border: 1px solid var(--d-rule); border-left: 5px solid var(--bx, var(--d-ink)); background: var(--bxb, var(--d-paper)); border-radius: 0 10px 10px 0; padding: 14px 20px 6px; scroll-margin-top: 90px; }
.d-box-h { display: flex; flex-wrap: wrap; align-items: baseline; gap: 4px 10px; margin-bottom: 8px; font-family: var(--d-sans); }
.d-box-k { font: 800 12.5px var(--d-nb); letter-spacing: .1em; text-transform: uppercase; color: var(--bx, var(--d-ink)); }
.d-box-t { font: 700 16.5px/1.3 var(--d-serif); color: var(--d-ink); }
.d-box-b > :last-child { margin-bottom: .8em; }
.d-box-tanim { --bx: var(--d-def); --bxb: var(--d-def-bg); }
.d-box-teorem, .d-box-yasa { --bx: var(--d-law); --bxb: var(--d-law-bg); }
.d-box-ornek { --bx: var(--d-ex); --bxb: var(--d-ex-bg); }
.d-box-problem { --bx: var(--d-pr); --bxb: #fff; border-left-width: 4px; }
.d-box-not, .d-box-ipucu { --bx: #4b5563; --bxb: #f3f2ee; }
.d-box-dikkat { --bx: var(--d-warn); --bxb: var(--d-warn-bg); }
.d-box-tarih { --bx: #8a6a2f; --bxb: #f7f1e4; }
.d-box-ozet { --bx: var(--d-ink); --bxb: #fff; }
.d-box .d-prose, .d-box p, .d-box li { font-size: 17.5px; }
.d-sol-inline { border-top: 1px dashed color-mix(in srgb, var(--bx) 45%, transparent); padding-top: 10px; margin-top: 4px; }
.d-sol-k, .d-sol summary { font: 800 12px var(--d-nb); letter-spacing: .1em; text-transform: uppercase; color: var(--bx); margin-bottom: 6px; }
.d-sol { border-top: 1px dashed var(--d-rule); margin: 4px 0 10px; padding-top: 8px; }
.d-sol summary { cursor: pointer; list-style: none; display: inline-flex; align-items: center; gap: 8px; padding: 7px 12px; border: 2px solid var(--d-pr); border-radius: 8px; background: var(--d-pr-bg); }
.d-sol summary::-webkit-details-marker { display: none; }
.d-sol summary::before { content: "＋"; font-weight: 800; }
.d-sol[open] summary::before { content: "－"; }
.d-sol-b { padding-top: 12px; }
.d-stars { margin-left: auto; color: var(--d-pr); letter-spacing: .1em; font-size: 14px; }

.d-pn { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin-top: 48px; }
.d-pn > a, .d-pn > span { display: flex; flex-direction: column; gap: 4px; padding: 16px 18px; border: var(--d-border); border-radius: 12px; background: #fff; color: inherit; text-decoration: none; box-shadow: var(--d-shadow); }
.d-pn > span:empty { visibility: hidden; }
.d-pn .next { text-align: right; }
.d-pn span span { font: 600 13px var(--d-sans); color: var(--d-mut); }
.d-pn b { font: 800 17px/1.25 var(--d-nb); }
.d-pn .soon { box-shadow: none; border-style: dashed; border-color: #a8a49b; color: #6b675f; }

/* aylık ücretsiz içerik sınırı */
.d-hide { display: none !important; }
.d-meter-bar { margin: 0 0 22px; padding: 10px 14px; border: var(--d-border); border-radius: 10px; background: #fff3c4; font: 600 14px/1.45 var(--d-sans); }
.d-meter-bar a { color: var(--d-ink); font-weight: 800; }
.d-gate { position: relative; margin: 10px 0 30px; padding: 28px 26px 24px; background: #fff; border: var(--d-border); border-radius: 16px; box-shadow: var(--d-shadow); text-align: center; }
.d-gate::before { content: ""; position: absolute; left: 0; right: 0; top: -130px; height: 130px; background: linear-gradient(rgba(248,244,234,0), var(--d-bg)); pointer-events: none; }
.d-gate-k { display: inline-block; margin: 0 0 10px; padding: 3px 10px; background: var(--d-hl); font: 800 12px/1.4 var(--d-nb); letter-spacing: .08em; text-transform: uppercase; }
.d-gate h2 { margin: 0 0 10px; font: 800 26px/1.15 var(--d-nb); }
.d-gate p { margin: 0 auto 16px; max-width: 34em; font: 400 15px/1.55 var(--d-sans); }
.d-gate-a { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; margin-bottom: 12px; }
.d-gate-n { font-size: 13px !important; color: var(--d-mut); margin-bottom: 0 !important; }
.d-gated .d-side a { pointer-events: none; opacity: .55; }

@media (max-width: 1000px) {
  .d-reader { grid-template-columns: minmax(0, 1fr); gap: 0; }
  .d-side { display: none; }
}
@media (max-width: 720px) {
  .d-cover { grid-template-columns: minmax(0, 1fr); gap: 22px; }
  .d-cover-art { width: 170px; }
  .d-ch-sec { columns: 1; margin-left: 0; }
  .d-ch > a, .d-ch > div { grid-template-columns: 40px minmax(0, 1fr); }
  .d-ch-n { font-size: 26px; }
  .d-prose { font-size: 17.5px; }
  .d-h2 { font-size: 25px; }
  .d-box { padding: 12px 14px 4px; margin-inline: -6px; }
  .d-pn { grid-template-columns: minmax(0, 1fr); }
  .d-facts div { padding-right: 16px; margin-right: 16px; }
  .d-facts dd { font-size: 28px; }
  .d-top-brand .logo { font-size: 24px; }
}
@media print {
  .d-top, .d-foot, .d-side, .d-pn { display: none !important; }
  body.fa-ders-focus { background: #fff; }
  .d-reader { display: block; }
  .d-sol { display: block; }
  .d-sol summary { display: none; }
}
@media (prefers-reduced-motion: reduce) { .fa-ders-focus * { transition: none !important; } }