*,*::before,*::after{box-sizing:border-box}
:root{
  --brand:#7355E8; --brand-600:#6342DA; --brand-700:#5435BE;
  --brand-50:#F3F0FF; --brand-100:#EAE4FF; --brand-200:#D6CCFF;
  --navy:#1B2366;
  --ink:#1E2336; --ink-soft:#5A6178; --ink-mute:#8A93A6;
  --bg:#F7F8FB; --card:#fff; --line:#ECEEF4; --plate:#fff;
  --shadow-sm:0 1px 2px rgba(30,35,54,.05);
  --shadow:0 2px 6px rgba(30,35,54,.06),0 12px 32px rgba(30,35,54,.07);
  --shadow-lg:0 8px 20px rgba(30,35,54,.09),0 28px 60px rgba(30,35,54,.11);
  --ring:0 0 0 3px var(--brand-200);
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --ink:#EDEFF6; --ink-soft:#B2B9CC; --ink-mute:#858EA3;
  --bg:#12141C; --card:#1A1D28; --line:#2A2E3C; --plate:#fff;
  --brand-50:#1F1A38; --brand-100:#2A2250; --brand-200:#3A2F6E;
  --shadow-sm:0 1px 2px rgba(0,0,0,.4);
  --shadow:0 2px 6px rgba(0,0,0,.4),0 12px 32px rgba(0,0,0,.34);
  --shadow-lg:0 8px 20px rgba(0,0,0,.45),0 28px 60px rgba(0,0,0,.4);
  --ring:0 0 0 3px rgba(115,85,232,.45);
}}
:root[data-theme="dark"]{
  --ink:#EDEFF6; --ink-soft:#B2B9CC; --ink-mute:#858EA3;
  --bg:#12141C; --card:#1A1D28; --line:#2A2E3C; --plate:#fff;
  --brand-50:#1F1A38; --brand-100:#2A2250; --brand-200:#3A2F6E;
  --shadow-sm:0 1px 2px rgba(0,0,0,.4);
  --shadow:0 2px 6px rgba(0,0,0,.4),0 12px 32px rgba(0,0,0,.34);
  --shadow-lg:0 8px 20px rgba(0,0,0,.45),0 28px 60px rgba(0,0,0,.4);
  --ring:0 0 0 3px rgba(115,85,232,.45);
}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
body{margin:0;background:var(--bg);color:var(--ink);
  font-family:"IBM Plex Sans Arabic",system-ui,-apple-system,"Segoe UI",sans-serif;
  line-height:1.85;font-size:16.5px;overflow-x:hidden}
.wrap{max-width:880px;margin:0 auto;padding:0 20px}
a{color:var(--brand);text-decoration:none}
a:hover{text-decoration:underline}
:focus-visible{outline:none;box-shadow:var(--ring);border-radius:10px}

/* ---------- header ---------- */
header.top{position:sticky;top:0;z-index:40;background:color-mix(in srgb,var(--card) 82%,transparent);
  backdrop-filter:saturate(1.6) blur(14px);-webkit-backdrop-filter:saturate(1.6) blur(14px);
  border-bottom:1px solid var(--line)}
header.top .wrap{display:flex;align-items:center;gap:12px;height:64px}
.brand{display:flex;align-items:center;gap:10px;color:var(--ink);font-weight:700;font-size:16px}
.brand:hover{text-decoration:none}
/* The logo artwork is dark navy on transparent, so it needs a light plate to
   stay legible when the page is in dark mode. */
.brand .plate{display:grid;place-items:center;width:38px;height:38px;border-radius:12px;
  background:var(--plate);box-shadow:var(--shadow-sm);flex:0 0 38px}
.brand .plate img{width:27px;height:27px;object-fit:contain;display:block}
.brand small{display:block;font-weight:500;font-size:11.5px;color:var(--ink-mute);line-height:1.2}
.spacer{flex:1}
.top-cta{background:var(--brand);color:#fff;padding:9px 17px;border-radius:12px;
  font-size:14px;font-weight:600;transition:transform .18s,background .18s}
.top-cta:hover{background:var(--brand-600);text-decoration:none;transform:translateY(-1px)}
.bar{position:absolute;inset-inline-start:0;bottom:-1px;height:2px;width:0;
  background:linear-gradient(90deg,var(--brand),var(--brand-200))}

/* ---------- hero ---------- */
.hero{position:relative;padding:58px 0 38px;text-align:center;overflow:hidden}
.hero::before{content:"";position:absolute;top:-180px;left:50%;transform:translateX(-50%);
  width:760px;height:430px;pointer-events:none;
  background:radial-gradient(closest-side,rgba(115,85,232,.17),transparent 72%)}
.hero-logo{width:132px;margin:0 auto 20px;padding:14px 18px;border-radius:22px;
  background:var(--plate);box-shadow:var(--shadow-lg);position:relative}
.hero-logo img{width:100%;height:auto;display:block}
.eyebrow{display:inline-flex;align-items:center;gap:7px;background:var(--brand-50);
  color:var(--brand-600);padding:6px 14px;border-radius:999px;font-size:13px;
  font-weight:600;margin-bottom:16px;position:relative}
.hero h1{margin:0 0 14px;font-size:clamp(27px,6vw,42px);line-height:1.28;
  letter-spacing:-.6px;position:relative}
.hero h1 .grad{background:linear-gradient(120deg,var(--brand),var(--navy));
  -webkit-background-clip:text;background-clip:text;color:transparent}
.hero p{margin:0 auto;max-width:620px;color:var(--ink-soft);font-size:16.5px;position:relative}

.stats{display:flex;justify-content:center;gap:10px;flex-wrap:wrap;margin:26px 0 4px;position:relative}
.stat{background:var(--card);border:1px solid var(--line);border-radius:15px;
  padding:12px 20px;min-width:104px;box-shadow:var(--shadow-sm)}
.stat b{display:block;font-size:21px;line-height:1.3;color:var(--brand-600)}
.stat span{font-size:12.5px;color:var(--ink-mute)}

/* ---------- cards & sections ---------- */
.card{background:var(--card);border:1px solid var(--line);border-radius:20px;box-shadow:var(--shadow)}
.bookcard{display:flex;gap:17px;align-items:center;padding:20px;margin:30px 0 8px}
.bookcard .cover{flex:0 0 56px;height:74px;border-radius:11px;display:grid;place-items:center;
  background:linear-gradient(145deg,var(--brand),var(--navy));color:#fff;font-size:25px;
  box-shadow:var(--shadow-sm)}
.bookcard h2{margin:0 0 3px;font-size:19px}
.bookcard .meta{color:var(--ink-mute);font-size:14px}

h2.sec{font-size:17px;margin:34px 0 14px;display:flex;align-items:center;gap:10px}
h2.sec::after{content:"";flex:1;height:1px;background:var(--line)}

.filter{position:relative;margin-bottom:14px}
.filter input{width:100%;padding:13px 44px 13px 16px;border:1px solid var(--line);
  border-radius:14px;background:var(--card);color:var(--ink);font:inherit;font-size:15px}
.filter input::placeholder{color:var(--ink-mute)}
.filter::before{content:"⌕";position:absolute;inset-inline-end:16px;top:50%;
  transform:translateY(-50%);color:var(--ink-mute);font-size:19px;pointer-events:none}
.nores{display:none;padding:22px;text-align:center;color:var(--ink-mute);font-size:14.5px}

ol.toc{list-style:none;margin:0;padding:0;display:grid;gap:10px}
ol.toc li.hide{display:none}
ol.toc a{display:flex;align-items:center;gap:14px;padding:14px 17px;background:var(--card);
  border:1px solid var(--line);border-radius:16px;color:var(--ink);
  transition:border-color .2s,box-shadow .2s,transform .2s}
ol.toc a:hover{border-color:var(--brand-200);box-shadow:var(--shadow);
  transform:translateX(-4px);text-decoration:none}
ol.toc .n{flex:0 0 34px;height:34px;border-radius:11px;background:var(--brand-50);
  color:var(--brand-600);display:grid;place-items:center;font-size:14px;font-weight:700}
ol.toc a:hover .n{background:var(--brand);color:#fff}
ol.toc .t{flex:1;font-weight:600;font-size:15.5px;line-height:1.5}
ol.toc .t em{display:block;font-style:normal;font-weight:500;font-size:12.5px;color:var(--ink-mute)}
ol.toc .p{color:var(--ink-mute);font-size:13px;white-space:nowrap}
ol.toc .arrow{color:var(--ink-mute);font-size:19px;transition:transform .2s}
ol.toc a:hover .arrow{transform:translateX(-3px);color:var(--brand)}

/* ---------- lesson page ---------- */
nav.crumb{font-size:13.5px;color:var(--ink-mute);padding:20px 0 0}
nav.crumb a{color:var(--ink-mute)}
.lesson-head{padding:14px 0 24px;border-bottom:1px solid var(--line);margin-bottom:22px}
.lesson-head h1{margin:0 0 12px;font-size:clamp(23px,5vw,33px);line-height:1.32;letter-spacing:-.4px}
.badges{display:flex;flex-wrap:wrap;gap:8px}
.badge{background:var(--card);border:1px solid var(--line);color:var(--ink-soft);
  padding:5px 12px;border-radius:999px;font-size:13px}
.badge.b{background:var(--brand-50);border-color:transparent;color:var(--brand-600);font-weight:600}

.tabs{display:flex;gap:6px;background:var(--card);border:1px solid var(--line);
  border-radius:16px;padding:6px;margin-bottom:20px;position:relative}
.tabs .ind{position:absolute;top:6px;bottom:6px;border-radius:11px;background:var(--brand);
  z-index:0;pointer-events:none}
.tabs button{flex:1;border:0;background:transparent;color:var(--ink-soft);font:inherit;
  font-size:15px;font-weight:600;padding:11px 8px;border-radius:11px;cursor:pointer;
  position:relative;z-index:1;transition:color .22s}
.tabs button[aria-selected="true"]{color:#fff}

.panel{display:none}
.panel.on{display:block}
.prose{background:var(--card);border:1px solid var(--line);border-radius:20px;
  padding:24px 26px;box-shadow:var(--shadow)}
.prose>:first-child{margin-top:0}
.prose>:last-child{margin-bottom:0}
.prose h2{font-size:18.5px;margin:28px 0 11px;padding-right:13px;
  border-right:4px solid var(--brand);line-height:1.5}
.prose h3{font-size:16px;margin:21px 0 8px}
.prose p{margin:0 0 13px}
.prose ul,.prose ol{margin:0 0 14px;padding-right:23px}
.prose li{margin-bottom:7px}
.prose li::marker{color:var(--brand)}
.prose strong{color:var(--ink);font-weight:700}
.prose code{background:var(--brand-50);color:var(--brand-600);padding:1px 6px;
  border-radius:6px;font-size:.92em}
.prose hr{border:0;border-top:1px solid var(--line);margin:22px 0}
.prose table{width:100%;border-collapse:collapse;margin:0 0 16px;font-size:15px}
.prose th,.prose td{border:1px solid var(--line);padding:9px 12px;text-align:right}
.prose th{background:var(--brand-50);color:var(--brand-600);font-weight:700}
.katex{font-size:1.05em}
.katex-display{overflow-x:auto;overflow-y:hidden;padding:4px 0}

/* ---------- illustrated tab ---------- */
.shots{display:grid;grid-template-columns:minmax(0,46%) minmax(0,1fr);gap:20px;align-items:start}
.viewer{position:sticky;top:80px}
.viewer iframe{width:100%;height:min(76vh,780px);border:1px solid var(--line);
  border-radius:16px;background:#fff;display:block;box-shadow:var(--shadow)}
.vhint{margin-top:8px;text-align:center;color:var(--ink-mute);font-size:12.5px}
.mobile-only{display:none}
.pageblock{padding:0 0 16px;margin:0 0 16px;border-bottom:1px solid var(--line)}
.pageblock:last-child{border-bottom:0;padding-bottom:0;margin-bottom:0}
.pageblock .say p{margin:0 0 11px}
.pageblock .say p:last-child{margin-bottom:0}
.showpage{display:inline-flex;align-items:center;gap:6px;background:var(--brand-50);
  color:var(--brand-600);border:1px solid transparent;font:inherit;font-size:13px;
  font-weight:700;padding:5px 12px;border-radius:999px;margin-bottom:10px;cursor:pointer;
  transition:background .18s,color .18s}
.showpage:hover{background:var(--brand-100)}
.showpage[aria-current="true"]{background:var(--brand);color:#fff}

.pdfbox{display:flex;flex-wrap:wrap;align-items:center;gap:14px;padding:18px 20px;margin:22px 0;
  background:var(--brand-50);border:1px solid var(--brand-100);border-radius:18px}
.pdfbox .ic{flex:0 0 42px;height:42px;border-radius:13px;background:var(--brand);color:#fff;
  display:grid;place-items:center;font-size:19px}
.pdfbox div{flex:1;min-width:190px}
.pdfbox b{display:block;font-size:15px}
.pdfbox span{color:var(--ink-soft);font-size:13.5px}
.btn{display:inline-flex;align-items:center;gap:7px;background:var(--brand);color:#fff;
  padding:11px 19px;border-radius:13px;font-weight:600;font-size:14.5px;white-space:nowrap;
  transition:transform .18s,background .18s;border:0;font-family:inherit;cursor:pointer}
.btn:hover{background:var(--brand-600);text-decoration:none;transform:translateY(-1px)}
.btn.ghost{background:transparent;color:var(--brand);border:1px solid var(--brand-200)}
.btn.ghost:hover{background:var(--brand-50)}

.cta{margin:38px 0;padding:30px 26px;border-radius:24px;text-align:center;position:relative;
  overflow:hidden;background:linear-gradient(135deg,var(--brand),var(--navy));color:#fff;
  box-shadow:var(--shadow-lg)}
.cta::after{content:"";position:absolute;width:300px;height:300px;border-radius:50%;
  background:rgba(255,255,255,.07);top:-150px;inset-inline-end:-80px}
.cta h3{margin:0 0 10px;font-size:21px;position:relative}
.cta p{margin:0 auto 18px;max-width:470px;color:rgba(255,255,255,.88);font-size:15px;position:relative}
.cta .btn{background:#fff;color:var(--brand-700);position:relative}
.cta .btn:hover{background:#F3F0FF}

.pager{display:flex;gap:12px;margin:28px 0}
.pager a{flex:1;padding:15px 17px;background:var(--card);border:1px solid var(--line);
  border-radius:16px;color:var(--ink);font-size:14.5px;transition:border-color .2s,transform .2s}
.pager a:hover{border-color:var(--brand-200);text-decoration:none;transform:translateY(-2px)}
.pager span{display:block;color:var(--ink-mute);font-size:12.5px;margin-bottom:2px}
.pager b{font-weight:600}

.totop{position:fixed;inset-inline-end:20px;bottom:20px;width:44px;height:44px;border-radius:14px;
  background:var(--card);border:1px solid var(--line);color:var(--ink-soft);box-shadow:var(--shadow);
  display:grid;place-items:center;font-size:19px;cursor:pointer;opacity:0;pointer-events:none;
  transition:opacity .25s,transform .25s;transform:translateY(8px);z-index:30}
.totop.on{opacity:1;pointer-events:auto;transform:translateY(0)}

footer{margin-top:50px;padding:30px 0 38px;border-top:1px solid var(--line);
  color:var(--ink-mute);font-size:13.5px;text-align:center}
footer a{color:var(--ink-soft)}
footer .row{margin-bottom:8px}
footer .flog{width:52px;margin:0 auto 14px;padding:8px 10px;border-radius:14px;
  background:var(--plate);box-shadow:var(--shadow-sm)}
footer .flog img{width:100%;height:auto;display:block}

@media (max-width:760px){
  .shots{grid-template-columns:1fr}
  /* The native PDF viewer does not render reliably in a frame on phones, so the
     frame is dropped there and each page links to the official book instead. */
  .viewer{display:none}
  .mobile-only{display:inline-flex}
}
@media (max-width:560px){
  body{font-size:16px}
  .wrap{padding:0 16px}
  .hero{padding:40px 0 30px}
  .prose{padding:19px 17px;border-radius:17px}
  .pager{flex-direction:column}
  ol.toc .p{display:none}
  .tabs button{font-size:13.5px;padding:10px 4px}
  .brand small{display:none}
}