/* Interactive textbook — shared stylesheet (derived from the Calculus I textbook) */

/* ---- base ---- */
:root{
  --ch:#2563eb; --ch2:#4f46e5; --ink:#1e293b; --muted:#64748b; --bg:#ffffff; --panel:#f8fafc; --line:#e2e8f0;
  --def:#2563eb; --def-bg:#eff6ff; --thm:#7c3aed; --thm-bg:#f5f3ff; --str:#059669; --str-bg:#ecfdf5;
  --warn:#d97706; --warn-bg:#fffbeb; --ex:#0f766e; --ex-bg:#f0fdfa; --sol-bg:#ffffff;
  --left:#dc2626; --right:#2563eb; --curve:#0f172a; --grid:#eef2f7; --axis:#94a3b8;
  --side-bg:#0f172a; --side-ink:#cbd5e1;
  --exam:#be123c; --exam-bg:#fff1f2; --exam-tag-bg:#ffe4e6;
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --ink:#e2e8f0; --muted:#94a3b8; --bg:#0b1220; --panel:#111a2e; --line:#23304a;
    --def-bg:#10203f; --thm-bg:#1d1640; --str-bg:#0c2a22; --warn-bg:#2a1f08; --ex-bg:#0b2826; --sol-bg:#0e172a;
    --curve:#e2e8f0; --grid:#1a2540; --axis:#475569; --left:#f87171; --right:#60a5fa;
    --exam:#fb7185; --exam-bg:#2a0f19; --exam-tag-bg:#4c1424;
  }
}
:root[data-theme="dark"]{
  --ink:#e2e8f0; --muted:#94a3b8; --bg:#0b1220; --panel:#111a2e; --line:#23304a;
  --def-bg:#10203f; --thm-bg:#1d1640; --str-bg:#0c2a22; --warn-bg:#2a1f08; --ex-bg:#0b2826; --sol-bg:#0e172a;
  --curve:#e2e8f0; --grid:#1a2540; --axis:#475569; --left:#f87171; --right:#60a5fa;
  --exam:#fb7185; --exam-bg:#2a0f19; --exam-tag-bg:#4c1424;
}
*{box-sizing:border-box}
:root{padding-top:env(safe-area-inset-top,0px);padding-bottom:env(safe-area-inset-bottom,0px)}
html{scroll-padding-top:env(safe-area-inset-top,0px)}
body{margin:0;background:var(--bg);color:var(--ink);font-family:'Crimson Pro',Georgia,'Times New Roman',serif;font-size:19px;line-height:1.65}
a{color:var(--ch)}
.page-wrapper{display:flex;min-height:100vh}
.sidebar{width:270px;flex:0 0 270px;background:var(--side-bg);color:var(--side-ink);position:sticky;top:0;height:100vh;overflow-y:auto;font-family:'Inter',system-ui,sans-serif;font-size:13.5px;padding:22px 14px 40px}
.sidebar-logo h2{margin:0;color:#fff;font-size:19px}
.sidebar-logo span{color:#94a3b8;font-size:12px}
.sidebar-logo{padding:0 8px 16px;border-bottom:1px solid #1e293b;margin-bottom:12px}
.ch-group{margin:14px 0 6px}
.ch-title{font-weight:700;font-size:12.5px;padding:4px 8px}
.sidebar a{display:block;color:var(--side-ink);text-decoration:none;padding:5px 10px;border-radius:6px;line-height:1.35}
.sidebar a:hover{background:#1e293b;color:#fff}
.sidebar a.active{background:var(--ch);color:#fff}
.menu-toggle{display:none;position:fixed;top:calc(10px + env(safe-area-inset-top,0px));left:10px;z-index:50;background:var(--ch);color:#fff;border:0;border-radius:8px;font-size:20px;padding:6px 12px;cursor:pointer}
.main-content{flex:1;min-width:0;max-width:980px;margin:0 auto;padding:0 34px 60px}
.hero{margin:0 -34px 30px;padding:46px 40px 40px;background:linear-gradient(125deg,#1d4ed8 0%,#4f46e5 55%,#7c3aed 100%);color:#fff;position:relative;overflow:hidden}
.hero svg.hero-art{position:absolute;right:-10px;bottom:-6px;width:340px;max-width:55%;opacity:.28}
.chapter-badge{display:inline-block;font-family:'Inter',sans-serif;font-size:13px;font-weight:600;background:rgba(255,255,255,.18);border:1px solid rgba(255,255,255,.35);padding:5px 12px;border-radius:999px}
.hero h1{font-size:44px;line-height:1.1;margin:14px 0 8px;font-weight:700}
.hero p{margin:0;max-width:600px;font-size:20px;opacity:.95}
h2{font-size:30px;margin:44px 0 10px;color:var(--ink);border-bottom:2px solid var(--line);padding-bottom:6px}
h3{font-size:23px;margin:28px 0 8px}
p{margin:12px 0}
.env{border-radius:12px;margin:22px 0;border:1px solid var(--line);overflow:hidden}
.env-header{font-family:'Inter',sans-serif;font-weight:700;font-size:15px;padding:12px 20px;display:flex;align-items:center;gap:8px}
.env-body{padding:16px 24px 20px}
.env-def{background:var(--def-bg);border-left:5px solid var(--def)} .env-def .env-header{color:var(--def)}
.env-thm{background:var(--thm-bg);border-left:5px solid var(--thm)} .env-thm .env-header{color:var(--thm)}
.env-strategy{background:var(--str-bg);border-left:5px solid var(--str)} .env-strategy .env-header{color:var(--str)}
.env-warn{background:var(--warn-bg);border-left:5px solid var(--warn)} .env-warn .env-header{color:var(--warn)}
.env-example{background:var(--ex-bg);border-left:5px solid var(--ex)} .env-example .env-header{color:var(--ex)}
/* 🎯 Exam corner (school courses): exam-style problems, each followed by its env-solution */
.env-exam{background:var(--exam-bg);border-left:5px solid var(--exam)} .env-exam .env-header{color:var(--exam);flex-wrap:wrap}
.exam-tags{display:flex;flex-wrap:wrap;gap:6px;margin:0 0 10px}
.env-header .exam-tags{margin:0 0 0 auto}
.exam-tag{display:inline-block;font-family:'Inter',sans-serif;font-size:11.5px;font-weight:700;letter-spacing:.02em;line-height:1.5;
  color:var(--exam);background:var(--exam-tag-bg);border:1px solid var(--exam);border-radius:999px;padding:1px 9px;white-space:nowrap}
.env-exam .env-body > p:first-child{margin-top:0}
.env-exam .env-solution{margin:10px 0 18px}
.env-solution{border:1px solid var(--line);border-radius:12px;margin:12px 0 26px;background:var(--sol-bg)}
.sol-toggle{font-family:'Inter',sans-serif;font-weight:600;font-size:14.5px;padding:12px 20px;cursor:pointer;display:flex;align-items:center;gap:8px;user-select:none;color:var(--ex)}
.sol-toggle:focus-visible,.btn:focus-visible,select:focus-visible,.quiz-opt:focus-visible{outline:3px solid #f59e0b;outline-offset:2px}
.toggle-arrow{margin-left:auto;transition:transform .2s}
.env-solution.open .toggle-arrow{transform:rotate(90deg)}
.sol-body{display:none;padding:4px 24px 20px;border-top:1px solid var(--line)}
.env-solution.open .sol-body{display:block}
.step{margin:14px 0}
.step-tag{display:inline-block;font-family:'Inter',sans-serif;font-size:12px;font-weight:700;background:var(--ch);color:#fff;border-radius:6px;padding:2px 9px;margin-right:8px;vertical-align:2px}
.step-tag.t2{background:#7c3aed}.step-tag.t3{background:#059669}.step-tag.t4{background:#d97706}
.figure-box{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:16px 18px;margin:18px 0}
.fig-cap{text-align:center;font-size:14px;color:var(--muted);font-family:'Inter',sans-serif;margin-top:8px}
.gsvg{display:block;width:100%;max-width:620px;height:auto;margin:0 auto}
.twocol{display:grid;grid-template-columns:1.1fr 1fr;gap:18px;align-items:center}
.scroll-x{overflow-x:auto}
table.vals{border-collapse:collapse;margin:12px auto;font-family:'Inter',sans-serif;font-size:14px;min-width:420px}
table.vals th,table.vals td{border:1px solid var(--line);padding:6px 12px;text-align:center}
table.vals th{background:var(--panel)}
table.vals td.l{color:var(--left)} table.vals td.r{color:var(--right)}
/* widgets */
.widget{border:2px solid var(--ch);border-radius:16px;margin:30px 0;background:var(--panel);overflow:hidden}
.widget-head{background:linear-gradient(90deg,#1d4ed8,#4f46e5);color:#fff;font-family:'Inter',sans-serif;font-weight:700;padding:12px 20px;display:flex;align-items:center;gap:10px;font-size:15.5px}
.live-dot{width:10px;height:10px;border-radius:50%;background:#4ade80;box-shadow:0 0 0 0 rgba(74,222,128,.7);animation:pulse 1.6s infinite}
@keyframes pulse{0%{box-shadow:0 0 0 0 rgba(74,222,128,.7)}70%{box-shadow:0 0 0 10px rgba(74,222,128,0)}100%{box-shadow:0 0 0 0 rgba(74,222,128,0)}}
@media (prefers-reduced-motion: reduce){.live-dot{animation:none}}
.widget-body{padding:18px 22px 22px}
.controls{display:flex;flex-wrap:wrap;gap:10px 14px;align-items:center;font-family:'Inter',sans-serif;font-size:14px;margin-bottom:12px}
.controls label{font-weight:600}
select{font-family:'Inter',sans-serif;font-size:14px;padding:6px 10px;border-radius:8px;border:1px solid var(--line);background:var(--bg);color:var(--ink);max-width:100%}
.btn{font-family:'Inter',sans-serif;font-size:14px;font-weight:600;border:0;border-radius:8px;padding:7px 16px;cursor:pointer;background:var(--ch);color:#fff}
.btn.ghost{background:transparent;color:var(--ch);border:1.5px solid var(--ch)}
input[type=range]{accent-color:var(--ch);width:180px}
.readouts{display:grid;grid-template-columns:repeat(auto-fit,minmax(170px,1fr));gap:10px;margin-top:12px;font-family:'Inter',sans-serif;font-size:14px}
.ro{background:var(--bg);border:1px solid var(--line);border-radius:10px;padding:10px 14px}
.ro b{display:block;font-size:12px;color:var(--muted);font-weight:600}
.ro span{font-size:17px;font-weight:700;font-variant-numeric:tabular-nums}
.ro.l span{color:var(--left)} .ro.r span{color:var(--right)}
.verdict{margin-top:12px;font-family:'Inter',sans-serif;font-size:15px;padding:10px 14px;border-radius:10px;background:var(--bg);border:1px dashed var(--ch)}
/* exercises */
.ex-card{border:1px solid var(--line);border-radius:14px;margin:22px 0;background:var(--bg);overflow:hidden}
.ex-head{display:flex;gap:14px;padding:16px 22px 6px}
.ex-num{flex:0 0 34px;height:34px;border-radius:10px;background:var(--ch);color:#fff;font-family:'Inter',sans-serif;font-weight:700;display:flex;align-items:center;justify-content:center}
.ex-prompt{flex:1;min-width:0;line-height:2}
.mini{margin:6px 22px 12px;border:1px solid var(--line);border-radius:12px;background:var(--panel);padding:12px 14px}
.mini .mini-title{font-family:'Inter',sans-serif;font-size:13px;font-weight:700;color:var(--ch);display:flex;align-items:center;gap:8px;margin-bottom:8px}
.ex-card .env-solution{margin:0 22px 18px}
.tf{display:inline-block;font-family:'Inter',sans-serif;font-size:12.5px;font-weight:700;padding:1px 8px;border-radius:6px;margin-right:6px}
.tf.t{background:#dcfce7;color:#166534}.tf.f{background:#fee2e2;color:#991b1b}
/* quiz */
.quiz-section{border:2px solid #7c3aed;border-radius:16px;padding:20px 24px;margin:40px 0;background:var(--thm-bg)}
.quiz-section h3{margin:0 0 4px;font-size:24px}
.quiz-progress{font-family:'Inter',sans-serif;font-size:14px;color:var(--muted);margin-bottom:10px}
.quiz-question{margin:18px 0;padding-top:12px;border-top:1px solid var(--line)}
.quiz-opts{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:8px}
/* a long formula scrolls inside its option / rule card instead of pushing past the page edge */
.quiz-opt,.rulecard{min-width:0;overflow-x:auto;overflow-y:hidden}
.quiz-opt{font-family:'Crimson Pro',serif;font-size:17px;text-align:left;padding:9px 14px;border-radius:10px;border:1.5px solid var(--line);background:var(--bg);color:var(--ink);cursor:pointer}
.quiz-opt:hover{border-color:#7c3aed}
.quiz-opt.correct{border-color:#16a34a;background:#dcfce7;color:#14532d}
.quiz-opt.wrong{border-color:#dc2626;background:#fee2e2;color:#7f1d1d}
.quiz-fb{font-family:'Inter',sans-serif;font-size:14px;margin-top:8px;min-height:1em}
.page-nav{display:flex;justify-content:space-between;margin:40px 0 20px;font-family:'Inter',sans-serif}
.page-nav a{text-decoration:none;font-weight:600;padding:8px 16px;border:1.5px solid var(--ch);border-radius:10px}
footer{font-family:'Inter',sans-serif;font-size:13px;color:var(--muted);border-top:1px solid var(--line);padding-top:16px}
@media (max-width:900px){
  .sidebar{position:fixed;left:-290px;z-index:40;transition:left .25s;top:0}
  .sidebar.show{left:0}
  .menu-toggle{display:block}
  .main-content{padding:0 16px 50px}
  .hero{margin:0 -16px 24px;padding:64px 20px 30px}
  .hero h1{font-size:34px}
  .twocol{grid-template-columns:1fr}
  .env-body{padding:14px 16px 18px}.sol-body{padding:4px 16px 18px}
  /* long inline formulas in steps/solutions scroll inside their box instead of widening the page */
  .sol-body,.env-body,.ex-prompt,.step,.quiz-q,.rtn-body{overflow-x:auto;overflow-y:hidden}
  .ex-head{padding:14px 14px 4px}.mini{margin:6px 12px 12px}.ex-card .env-solution{margin:0 12px 14px}
  body{font-size:18px}
}

/* ---- section pages ---- */
.widget table.vals,.mini table.vals{min-width:0;font-size:13px}
.widget table.vals th,.widget table.vals td,.mini table.vals th,.mini table.vals td{padding:5px 8px}
.twopanel{display:grid;grid-template-columns:1fr 1fr;gap:16px}
.threepanel{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}
@media (max-width:860px){.threepanel{grid-template-columns:1fr}}
@media (max-width:760px){.twopanel{grid-template-columns:1fr}}
.panel-cap{font-family:'Inter',sans-serif;font-size:13px;font-weight:700;color:var(--muted);text-align:center;margin-bottom:4px}
.partlist{margin:6px 0 0;padding-left:0;list-style:none}
.partlist li{margin:10px 0;line-height:1.9}
.pnum{display:inline-block;font-family:'Inter',sans-serif;font-size:12px;font-weight:700;background:var(--panel);border:1px solid var(--line);color:var(--muted);border-radius:6px;padding:1px 8px;margin-right:8px}
.rulegrid{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:12px;margin:10px 0}
.rulecard{border:1px solid var(--line);border-radius:10px;padding:10px 14px;background:var(--bg)}
.rulecard b{font-family:'Inter',sans-serif;font-size:13px;color:var(--thm);display:block;margin-bottom:2px}
.flag{display:inline-block;font-family:'Inter',sans-serif;font-size:12.5px;font-weight:700;border-radius:6px;padding:2px 9px}
.flag.up{background:#dcfce7;color:#166534}.flag.down{background:#fee2e2;color:#991b1b}
.note-book{font-family:'Inter',sans-serif;font-size:13.5px;border-left:4px solid var(--warn);background:var(--warn-bg);padding:8px 12px;border-radius:8px;margin:10px 0}
.ex-prompt{line-height:1.9}

.widget .twocol{grid-template-columns:1.2fr 1fr;gap:14px}
.answer{font-family:'Inter',sans-serif;font-size:14px;margin-top:10px;padding:10px 14px;border-radius:10px;background:var(--str-bg);border:1px solid var(--str)}
.env-body ul{margin:6px 0;padding-left:22px}.env-body ul li{margin:4px 0}

.opbox{display:grid;grid-template-columns:1fr 1fr;gap:16px;margin:20px 0}
@media (max-width:760px){.opbox{grid-template-columns:1fr}}

/* ---- chapter intro pages ---- */
.sec-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:16px;margin:18px 0 26px}
.sec-card{display:flex;flex-direction:column;border:1px solid var(--line);border-top:5px solid var(--cc);border-radius:14px;padding:16px 18px;background:var(--panel);text-decoration:none;color:var(--ink);transition:transform .15s,box-shadow .15s}
.sec-card:hover{transform:translateY(-3px);box-shadow:0 10px 24px rgba(15,23,42,.12)}
.sec-card .n{font-family:Inter,sans-serif;font-size:12px;font-weight:700;color:var(--cc);letter-spacing:.05em;text-transform:uppercase}
.sec-card h3{margin:4px 0 6px;font-size:21px;line-height:1.25}
.sec-card p{margin:0 0 10px;font-size:16.5px;color:var(--muted);line-height:1.45;flex:1}
.sec-card .key{font-size:15px;background:var(--bg);border:1px dashed var(--line);border-radius:8px;padding:6px 10px;margin-bottom:10px;overflow-x:auto}
.sec-card .go{font-family:Inter,sans-serif;font-size:13.5px;font-weight:700;color:var(--ch)}
.chain{display:flex;flex-wrap:wrap;align-items:center;gap:8px;font-family:Inter,sans-serif;font-size:13.5px;margin:10px 0 22px}
.chain span.b{background:var(--panel);border:1px solid var(--line);border-left:4px solid var(--cc);border-radius:8px;padding:7px 11px;font-weight:600}
.chain span.a{color:var(--muted);font-weight:700}
.outcomes li{margin:4px 0}
.dq{border:1px solid var(--line);border-radius:12px;padding:12px 16px;margin:12px 0;background:var(--panel)}
.dq .qopts{display:flex;flex-wrap:wrap;gap:8px;margin-top:8px}
.dq button{font-family:Inter,sans-serif;font-size:14.5px;border:1px solid var(--line);background:var(--bg);color:var(--ink);border-radius:9px;padding:7px 12px;cursor:pointer}
.dq button:hover{border-color:var(--ch)}
.dq button.ok{background:#dcfce7;border-color:#16a34a;color:#166534}.dq button.no{background:#fee2e2;border-color:#dc2626;color:#991b1b}
.dq .why{font-family:Inter,sans-serif;font-size:13.5px;color:var(--muted);margin-top:6px}
#diag-result{font-family:Inter,sans-serif;border-radius:12px;padding:14px 18px;background:var(--str-bg);border:1px solid var(--str);display:none}
.pill{display:inline-block;min-width:44px;text-align:center;font-family:Inter,sans-serif;font-size:13px;font-weight:600;background:var(--panel);border:1px solid var(--line);border-radius:999px;padding:2px 8px}

/* ---- home / formulas / glossary ---- */
.fsearch{display:flex;gap:10px;flex-wrap:wrap;align-items:center;margin:0 0 18px;position:sticky;top:0;z-index:20;background:var(--bg);padding:10px 0;border-bottom:1px solid var(--line)}
.fsearch input{flex:1;min-width:220px;font-family:Inter,sans-serif;font-size:15px;padding:10px 14px;border:1px solid var(--line);border-radius:10px;background:var(--panel);color:var(--ink)}
.fsearch .chips a{font-family:Inter,sans-serif;font-size:12.5px;font-weight:600;text-decoration:none;border:1px solid var(--line);border-radius:999px;padding:4px 10px;margin:2px;display:inline-block;color:var(--ink);background:var(--panel)}
.fgrid{display:grid;grid-template-columns:repeat(auto-fill,minmax(290px,1fr));gap:12px;margin:10px 0 28px}
.fcard{border:1px solid var(--line);border-left:5px solid var(--cc,var(--ch));border-radius:12px;padding:10px 14px;background:var(--panel)}
.fcard .ft{font-family:Inter,sans-serif;font-size:12.5px;font-weight:700;color:var(--cc,var(--ch));display:flex;justify-content:space-between;gap:6px}
.fcard .ft a{font-weight:600;text-decoration:none;font-size:12px}
.fcard .fb{overflow-x:auto;font-size:16.5px;padding-bottom:2px;display:flex;flex-wrap:wrap;align-items:center;gap:2px 22px}
.fcard.wide{grid-column:span 2}
@media (max-width:760px){.fcard.wide{grid-column:span 1}}
.fcard .fn{font-family:Inter,sans-serif;font-size:12.5px;color:var(--muted)}
.gtable{width:100%;border-collapse:collapse;font-size:16.5px}
.gtable th,.gtable td{border-bottom:1px solid var(--line);padding:8px 10px;text-align:left;vertical-align:top}
.gtable th{font-family:Inter,sans-serif;font-size:13px;color:var(--muted);background:var(--bg)}
.gtable td.ar{font-family:'Noto Naskh Arabic',serif;font-size:21px;color:var(--thm);direction:rtl;text-align:right;white-space:nowrap}
.gtable td.l2{font-size:18px;color:var(--thm);white-space:nowrap}
.gtable td.l2[dir="rtl"]{text-align:right}
.gtable td.en{font-weight:700;color:var(--ch);white-space:nowrap}
.gtable td.w a{font-family:Inter,sans-serif;font-size:12.5px;margin-right:6px}
.gtable tr:target{background:var(--warn-bg)}
.gcat{font-family:Inter,sans-serif;font-size:13px;font-weight:700;color:#fff;background:var(--ch);padding:6px 12px;border-radius:8px;margin:22px 0 6px;display:inline-block}
.flash{display:flex;flex-direction:column;align-items:center;gap:12px}
.fcardx{width:min(460px,100%);min-height:180px;border-radius:16px;border:1px solid var(--line);background:var(--panel);display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center;padding:20px;cursor:pointer;box-shadow:0 8px 20px rgba(15,23,42,.08)}
.fcardx .big{font-size:30px;font-weight:700;color:var(--ch)}
.fcardx .arb{font-family:'Noto Naskh Arabic',serif;font-size:34px;color:var(--thm)}
.fcardx .mean{font-size:19px;line-height:1.5;max-width:400px}
.fcardx .big + .mean{margin-top:10px}
.fcardx .hint{font-family:Inter,sans-serif;font-size:12.5px;color:var(--muted);margin-top:8px}
.hgrid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:16px;margin:16px 0 26px}
.hcard{border:1px solid var(--line);border-top:6px solid var(--cc);border-radius:14px;padding:16px 18px;background:var(--panel)}
.hcard h3{margin:2px 0 8px;font-size:21px}.hcard h3 a{text-decoration:none;color:var(--ink)}
.hcard ul{margin:0;padding-left:18px;font-size:16.5px}.hcard li{margin:3px 0}
.hcard .cn{font-family:Inter,sans-serif;font-size:12px;font-weight:700;letter-spacing:.05em;color:var(--cc);text-transform:uppercase}
.feat{display:grid;grid-template-columns:repeat(auto-fill,minmax(210px,1fr));gap:12px;margin:14px 0 24px}
.feat div{font-family:Inter,sans-serif;font-size:14px;border:1px solid var(--line);border-radius:12px;padding:12px 14px;background:var(--panel)}
.feat b{display:block;font-size:15px;margin-bottom:4px}
.start-btn{display:inline-block;font-family:Inter,sans-serif;font-weight:700;background:#fff;color:#1d4ed8;padding:10px 20px;border-radius:10px;text-decoration:none;margin-top:14px}
kbd{font-family:Inter,monospace;font-size:12px;border:1px solid var(--line);border-bottom-width:2px;border-radius:5px;padding:1px 6px;background:var(--panel)}

/* ---- enhancements: glossary tooltips, toolbar, toc ---- */
/* ===== Textbook enhancements ===== */
.gl{border-bottom:1.5px dotted var(--ch);cursor:help;border-radius:2px;transition:background .15s}
.gl:hover,.gl:focus{background:rgba(37,99,235,.10);outline:none}
.gl:focus-visible{outline:2px solid #f59e0b;outline-offset:1px}
body.gl-ar .gl::after{content:" (" attr(data-ar) ")";font-family:'Noto Naskh Arabic','Tajawal',serif;font-size:.78em;color:var(--thm);white-space:nowrap}
body.gl-ar .gl:not([data-ar])::after{content:none}
/* second glossary language other than Arabic (book.json "glossary_lang"): no Arabic font */
body.gl-l2x.gl-ar .gl::after,body.gl-l2x #gl-tip .gl-arw,body.gl-l2x .fcardx .arb{font-family:inherit}
body.gl-l2x #gl-tip .gl-arw{text-align:start;font-size:17px}
body.gl-l2x .fcardx .arb{font-size:28px}
#gl-tip{position:fixed;z-index:200;display:none;background:var(--bg);color:var(--ink);border:1px solid var(--line);border-top:4px solid var(--ch);border-radius:12px;box-shadow:0 12px 32px rgba(15,23,42,.22);padding:12px 14px 10px;font-family:'Inter',system-ui,sans-serif;font-size:13.5px;line-height:1.45}
#gl-tip.on{display:block}
#gl-tip .gl-top{display:flex;justify-content:space-between;align-items:baseline;gap:8px}
#gl-tip .gl-en{font-weight:700;font-size:15px;color:var(--ch);text-transform:capitalize}
#gl-tip .gl-cat{font-size:11px;color:var(--muted);text-transform:uppercase;letter-spacing:.04em}
#gl-tip .gl-arw{font-family:'Noto Naskh Arabic','Tajawal',serif;font-size:21px;font-weight:600;color:var(--thm);margin:4px 0 6px;text-align:right}
#gl-tip .gl-d{color:var(--ink)}
#gl-tip .gl-more{display:none;margin-top:8px;font-size:12.5px;font-weight:600;text-decoration:none}
#gl-tip.pinned .gl-more{display:inline-block}
.tda-tools{position:fixed;right:14px;bottom:calc(14px + env(safe-area-inset-bottom,0px));z-index:120;display:flex;flex-direction:column;gap:8px}
.tda-tools button{width:42px;height:42px;border-radius:50%;border:1px solid var(--line);background:var(--bg);color:var(--ink);font-size:18px;font-weight:700;cursor:pointer;box-shadow:0 4px 14px rgba(15,23,42,.18);display:flex;align-items:center;justify-content:center;font-family:'Noto Naskh Arabic','Inter',sans-serif}
.tda-tools button:hover{border-color:var(--ch);color:var(--ch)}
.tda-tools button:focus-visible{outline:3px solid #f59e0b;outline-offset:2px}
.tda-tools button[aria-pressed="true"]{background:var(--thm);color:#fff;border-color:var(--thm)}
.tda-tools #tda-top{opacity:0;pointer-events:none;transition:opacity .2s}
.tda-tools.scrolled #tda-top{opacity:1;pointer-events:auto}
.tda-progress{position:fixed;top:0;left:0;height:3px;width:0;background:linear-gradient(90deg,#2563eb,#7c3aed);z-index:150;pointer-events:none}
.side-search{width:100%;margin:4px 0 6px;padding:8px 10px;border-radius:8px;border:1px solid #1e293b;background:#111827;color:#e2e8f0;font-family:'Inter',sans-serif;font-size:13px}
.side-search::placeholder{color:#64748b}
.side-hint{font-size:11px;color:#64748b;padding:0 4px 6px}
.sidebar a.intro-link{font-style:italic;opacity:.9}
:root[data-theme="dark"] .hero, :root[data-theme="dark"] body{color-scheme:dark}
@media (max-width:900px){ .tda-tools{right:10px;bottom:calc(10px + env(safe-area-inset-bottom,0px))} .tda-tools button{width:38px;height:38px;font-size:16px} }
@media print{
  .sidebar,.menu-toggle,.tda-tools,.tda-progress,#gl-tip,.page-nav,.controls button{display:none!important}
  .page-wrapper{display:block}.main-content{max-width:none;padding:0}
  .hero{-webkit-print-color-adjust:exact;print-color-adjust:exact}
  .env-solution .sol-body{display:block!important}
  .gl{border-bottom:none}
  .widget,.env,.ex-card{break-inside:avoid}
  body{font-size:12pt}
}
.hero .gl{border-bottom-color:rgba(255,255,255,.75)}
.hero .gl:hover,.hero .gl:focus{background:rgba(255,255,255,.15)}
body.gl-ar .hero .gl::after{color:#fde68a}
.tda-toc{display:flex;flex-wrap:wrap;gap:6px 8px;align-items:center;font-family:Inter,sans-serif;font-size:12.5px;margin:-12px 0 22px;padding:10px 12px;border:1px solid var(--line);border-radius:12px;background:var(--panel)}
.tda-toc b{color:var(--muted);font-size:12px;margin-right:4px}
.tda-toc a{text-decoration:none;border:1px solid var(--line);background:var(--bg);border-radius:999px;padding:3px 10px;color:var(--ink)}
.tda-toc a:hover{border-color:var(--ch);color:var(--ch)}
@media print{.tda-toc{display:none}}

/* ---- research-teaching nexus ---- */
.rtn{border:1px solid var(--line);border-left:5px solid #6a2c91;border-radius:12px;margin:30px 0;background:var(--panel);overflow:hidden}
.rtn-head{background:#6a2c91;color:#fff;font-family:'Inter',sans-serif;font-weight:700;padding:10px 18px;display:flex;flex-wrap:wrap;gap:6px 14px;justify-content:space-between;align-items:center;font-size:15px}
.rtn-head small{font-weight:500;opacity:.9;font-size:12.5px}
.rtn-body{padding:14px 22px 16px}.rtn-body p{margin:8px 0}.rtn-body ol{margin:6px 0 8px;padding-left:22px}.rtn-body li{margin:4px 0}
.rtn-label{font-family:'Inter',sans-serif;font-weight:700;font-size:13.5px;color:#6a2c91}
:root[data-theme="dark"] .rtn-label{color:#c9a5ec}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]) .rtn-label{color:#c9a5ec}}
.rtn-note{font-family:'Inter',sans-serif;font-size:13px;color:var(--muted);border-top:1px dashed var(--line);padding-top:8px;margin-top:10px}

/* keep wide display math from forcing page-level horizontal scroll on phones */
mjx-container[display="true"]{display:block;max-width:100%;overflow-x:auto;overflow-y:hidden}