/* ============================================================
   JOVANA EDUCATION — Document reader
   Builds on styles.css (tokens, nav, footer, buttons, reveals).
   Layout for: doc hero · sticky reading controls · in-depth
   introduction · the original source text · facts aside · related.
   ============================================================ */

/* ---------- Reading progress ---------- */
.read-progress{
  position:fixed; top:0; left:0; height:3px; width:0%;
  background:var(--grad); z-index:200; transition:width .12s linear;
  box-shadow:0 0 12px -2px color-mix(in srgb, var(--accent-1) 70%, transparent);
}

/* ---------- Breadcrumb / back ---------- */
.doc-top{ padding-top:104px; }
.crumb{ display:inline-flex; align-items:center; gap:9px; font-size:13px; font-weight:600; letter-spacing:.04em; color:var(--ink-faint); transition:color .2s; }
.crumb:hover{ color:var(--accent-ink); }
.crumb svg{ width:15px; height:15px; }

/* ---------- Document hero ---------- */
.doc-hero{ padding:26px 0 clamp(34px,5vh,56px); border-bottom:1px solid var(--line); position:relative; }
.doc-hero .aura{ position:absolute; inset:-40px 0 0; background:var(--aura); opacity:.7; pointer-events:none; z-index:0; }
.doc-hero > *{ position:relative; z-index:1; }
.doc-kicker{ display:inline-flex; align-items:center; gap:11px; margin-bottom:20px; }
.doc-kicker .dk-glyph{ width:30px; height:30px; color:var(--accent-1); flex-shrink:0; }
.doc-kicker .dk-field{ font-size:12.5px; font-weight:700; letter-spacing:.16em; text-transform:uppercase; color:var(--accent-ink); }
.doc-kicker .dk-sep{ width:4px; height:4px; border-radius:50%; background:var(--ink-faint); opacity:.6; }
.doc-kicker .dk-year{ font-family:var(--font-display); font-style:italic; font-size:18px; color:var(--ink-faint); }

.doc-title{ font-family:var(--font-display); font-weight:600; font-size:clamp(33px,4.8vw,60px); line-height:1.1; letter-spacing:-.01em; max-width:22ch; }
html[data-lang="zh"] .doc-title, html[data-lang="zhHant"] .doc-title{ line-height:1.22; letter-spacing:0; }
.doc-author{ font-family:var(--font-display); font-style:italic; font-size:clamp(18px,2vw,23px); color:var(--ink-soft); margin-top:22px; }
.doc-essence{ font-size:clamp(17px,1.5vw,20px); color:var(--ink-soft); line-height:1.6; max-width:60ch; margin-top:22px; }
.doc-formula{ font-family:var(--font-display); font-style:italic; font-size:clamp(30px,4vw,52px); line-height:1; margin-top:26px;
  background:var(--grad); -webkit-background-clip:text; background-clip:text; -webkit-text-fill-color:transparent; color:transparent; }
.doc-formula:empty{ display:none; }

.doc-metarow{ display:flex; flex-wrap:wrap; gap:10px 12px; margin-top:30px; }
.doc-chip{ display:inline-flex; align-items:center; gap:8px; padding:8px 14px; border-radius:999px; border:1px solid var(--line); background:var(--surface-2); font-size:12.5px; color:var(--ink-soft); font-weight:500; }
.doc-chip svg{ width:14px; height:14px; color:var(--accent-1); opacity:.85; }
.doc-chip b{ font-weight:700; color:var(--ink); }

/* ---------- Layout ---------- */
.doc-layout{ display:grid; grid-template-columns:minmax(0,1fr) 312px; gap:clamp(36px,5vw,72px); padding-block:clamp(40px,6vh,72px); align-items:start; }
.doc-main{ min-width:0; }

/* ---------- Reading controls (sticky) ---------- */
.read-controls{ position:sticky; top:84px; z-index:40; display:flex; flex-wrap:wrap; align-items:center; justify-content:space-between; gap:14px;
  padding:12px; border-radius:16px; border:1px solid var(--line); margin-bottom:34px;
  background:color-mix(in srgb, var(--surface-2) 92%, transparent);
  -webkit-backdrop-filter:blur(18px) saturate(1.5); backdrop-filter:blur(18px) saturate(1.5); box-shadow:var(--shadow-sm); }
.rc-label{ font-size:11px; font-weight:700; letter-spacing:.14em; text-transform:uppercase; color:var(--ink-faint); padding-left:6px; }
html[data-lang="zh"] .rc-label, html[data-lang="zhHant"] .rc-label{ letter-spacing:.06em; }
.lvl-seg{ display:flex; gap:4px; padding:4px; border-radius:11px; background:var(--bg-warm); border:1px solid var(--line-soft); flex:1; min-width:240px; }
.lvl-seg button{ flex:1; display:flex; flex-direction:column; align-items:flex-start; gap:1px; padding:9px 13px; border-radius:8px; text-align:left; transition:background .22s, color .22s, box-shadow .22s; }
.lvl-seg button .k{ font-size:9.5px; font-weight:700; letter-spacing:.12em; text-transform:uppercase; color:var(--ink-faint); }
.lvl-seg button .t{ font-family:var(--font-display); font-size:17px; font-weight:600; color:var(--ink-soft); }
.lvl-seg button:hover .t{ color:var(--ink); }
.lvl-seg button.on{ background:var(--surface-2); box-shadow:0 1px 3px rgba(0,0,0,.1); }
.lvl-seg button.on .k{ color:var(--accent-ink); }
.lvl-seg button.on .t{ color:var(--ink); }
.rc-lang{ display:inline-flex; align-items:center; gap:7px; padding:9px 13px; border-radius:10px; border:1px solid var(--line); background:var(--surface-2); font-size:13px; font-weight:600; color:var(--ink-soft); transition:border-color .2s, color .2s; }
.rc-lang:hover{ border-color:var(--accent-1); color:var(--ink); }
.rc-lang svg{ width:15px; height:15px; opacity:.8; }

/* ---------- Section heading ---------- */
.sec-eyebrow{ display:inline-flex; align-items:center; gap:11px; font-size:12px; font-weight:700; letter-spacing:.18em; text-transform:uppercase; color:var(--accent-ink); margin-bottom:18px; }
.sec-eyebrow::before{ content:""; width:26px; height:1px; background:var(--accent-1); }
html[data-lang="zh"] .sec-eyebrow, html[data-lang="zhHant"] .sec-eyebrow{ letter-spacing:.08em; }

/* ---------- In-depth introduction ---------- */
.intro{ margin-bottom:clamp(48px,7vh,84px); }
.intro-body{ transition:opacity .35s ease, transform .35s ease; }
.intro-body.swap{ opacity:0; transform:translateY(10px); }
.intro-section{ margin-bottom:30px; }
.intro-section:last-child{ margin-bottom:0; }
.intro-section h3{ font-family:var(--font-display); font-weight:600; font-size:clamp(22px,2.4vw,30px); line-height:1.18; margin-bottom:14px; }
.intro-section p{ font-size:clamp(17px,1.35vw,19.5px); line-height:1.72; color:var(--ink-soft); margin-bottom:14px; max-width:66ch; }
.intro-section p:last-child{ margin-bottom:0; }
.intro-section p.lead{ font-family:var(--font-display); font-size:clamp(21px,2.2vw,27px); line-height:1.4; color:var(--ink); font-weight:500; max-width:30ch; }
html[data-lang="zh"] .intro-section p.lead, html[data-lang="zhHant"] .intro-section p.lead{ max-width:24ch; line-height:1.5; }

/* lead-in section (the "in one sentence" block) gets accent treatment */
.intro-section.is-lead{ padding-left:24px; border-left:2px solid; border-image:var(--grad) 1; }

/* ---------- The original source ---------- */
.original{ position:relative; border:1px solid var(--line); border-radius:20px; overflow:hidden; background:var(--surface-2); box-shadow:var(--shadow-md); }
.orig-head{ display:flex; flex-wrap:wrap; align-items:center; justify-content:space-between; gap:12px; padding:18px clamp(22px,3vw,38px); background:var(--grad-soft); border-bottom:1px solid var(--line-soft); }
.orig-head .oh-l{ display:inline-flex; align-items:center; gap:10px; font-size:12px; font-weight:700; letter-spacing:.14em; text-transform:uppercase; color:var(--accent-ink); }
html[data-lang="zh"] .orig-head .oh-l, html[data-lang="zhHant"] .orig-head .oh-l{ letter-spacing:.06em; }
.orig-head .oh-l .seal{ width:9px; height:9px; border-radius:50%; background:var(--grad); box-shadow:0 0 0 4px color-mix(in srgb, var(--accent-1) 16%, transparent); }
.orig-note{ font-family:var(--font-display); font-style:italic; font-size:14px; color:var(--ink-faint); }

.orig-body{ padding:clamp(28px,4vw,52px) clamp(24px,4vw,60px); position:relative; }
.orig-body::before{ content:""; position:absolute; left:0; top:0; bottom:0; width:1px; background:var(--line-soft); margin-left:clamp(24px,4vw,60px); opacity:.0; }
.ob-meta{ font-family:var(--font-mono); font-size:12.5px; letter-spacing:.04em; color:var(--ink-faint); text-transform:none; padding-bottom:22px; margin-bottom:26px; border-bottom:1px dashed var(--line); }
.ob-h{ font-family:var(--font-display); font-style:italic; font-weight:600; font-size:clamp(18px,2vw,23px); color:var(--accent-ink); margin:34px 0 14px; }
.ob-h:first-child{ margin-top:0; }
.ob-p{ font-family:var(--font-display); font-size:clamp(19px,1.7vw,22px); line-height:1.78; color:var(--ink); margin-bottom:18px; }
.ob-q{ font-family:var(--font-display); font-style:italic; font-weight:500; font-size:clamp(23px,2.8vw,33px); line-height:1.32; color:var(--ink); margin:30px 0; padding-left:26px; border-left:3px solid; border-image:var(--grad) 1; max-width:34ch; }
.ob-sig{ font-family:var(--font-display); font-style:italic; font-size:16px; color:var(--ink-faint); margin-top:30px; text-align:right; }
.orig-source{ display:flex; padding:0 clamp(24px,4vw,60px) clamp(26px,4vw,44px); }
.orig-source a{ display:inline-flex; align-items:center; gap:9px; font-size:14px; font-weight:600; color:var(--accent-ink); padding:11px 18px; border-radius:999px; border:1px solid color-mix(in srgb, var(--accent-1) 32%, transparent); background:var(--surface); transition:background .2s, transform .2s, border-color .2s; }
.orig-source a:hover{ background:var(--grad-soft); transform:translateY(-1px); border-color:var(--accent-1); }
.orig-source a .ex{ transition:transform .2s; }
.orig-source a:hover .ex{ transform:translate(2px,-2px); }

/* ---------- Aside ---------- */
.doc-aside{ position:sticky; top:96px; display:flex; flex-direction:column; gap:18px; }
.aside-card{ border:1px solid var(--line); border-radius:16px; background:var(--surface-2); padding:22px 22px 24px; box-shadow:var(--shadow-sm); }
.aside-card h4{ font-size:11px; font-weight:700; letter-spacing:.14em; text-transform:uppercase; color:var(--ink-faint); margin-bottom:16px; }
html[data-lang="zh"] .aside-card h4, html[data-lang="zhHant"] .aside-card h4{ letter-spacing:.06em; }
.fact{ padding:11px 0; border-top:1px solid var(--line-soft); }
.fact:first-of-type{ border-top:none; padding-top:0; }
.fact .fk{ font-size:11px; letter-spacing:.1em; text-transform:uppercase; color:var(--ink-faint); font-weight:600; }
.fact .fv{ font-size:14.5px; color:var(--ink); margin-top:4px; line-height:1.5; }
.aside-sig{ font-size:14px; color:var(--ink-soft); line-height:1.6; font-style:italic; font-family:var(--font-display); font-size:17px; }

.aside-levels .al-row{ display:flex; align-items:center; gap:10px; width:100%; padding:11px 12px; border-radius:10px; border:1px solid var(--line); background:var(--surface); margin-bottom:8px; transition:border-color .2s, background .2s, transform .15s; text-align:left; }
.aside-levels .al-row:last-child{ margin-bottom:0; }
.aside-levels .al-row:hover{ border-color:var(--accent-1); transform:translateX(2px); }
.aside-levels .al-row.on{ background:var(--grad-soft); border-color:transparent; box-shadow:inset 0 0 0 1.5px color-mix(in srgb,var(--accent-1) 55%,transparent); }
.aside-levels .al-dots{ display:inline-flex; gap:3px; }
.aside-levels .al-dots i{ width:6px; height:6px; border-radius:50%; background:var(--line); }
.aside-levels .al-row[data-lv="expert"] .al-dots i{ background:var(--accent-1); }
.aside-levels .al-row[data-lv="general"] .al-dots i:nth-child(-n+2){ background:var(--accent-1); }
.aside-levels .al-row[data-lv="age12"] .al-dots i:first-child{ background:var(--accent-1); }
.aside-levels .al-row .al-t{ font-family:var(--font-display); font-size:16px; font-weight:600; }
.aside-levels .al-row .al-time{ margin-left:auto; font-size:12px; color:var(--ink-faint); }

/* ---------- Related ---------- */
.related{ border-top:1px solid var(--line); padding-block:clamp(48px,7vh,82px); }
.related-grid{ display:grid; grid-template-columns:repeat(auto-fill,minmax(300px,1fr)); gap:16px; margin-top:30px; }
.rel-card{ position:relative; display:flex; flex-direction:column; border:1px solid var(--line); border-radius:15px; background:var(--surface-2); padding:24px 24px 22px; transition:transform .3s, box-shadow .3s, border-color .3s; min-height:178px; }
.rel-card:hover{ transform:translateY(-4px); box-shadow:var(--shadow-md); border-color:var(--accent-1); }
.rel-card .rc-field{ font-size:11px; font-weight:700; letter-spacing:.12em; text-transform:uppercase; color:var(--accent-ink); }
.rel-card .rc-title{ font-family:var(--font-display); font-weight:600; font-size:21px; line-height:1.2; margin:12px 0 6px; }
.rel-card .rc-author{ font-size:13px; color:var(--ink-faint); font-style:italic; font-family:var(--font-display); }
.rel-card .rc-open{ margin-top:auto; padding-top:18px; font-size:13px; font-weight:600; color:var(--accent-ink); display:inline-flex; align-items:center; gap:7px; opacity:.6; transition:opacity .2s, gap .2s; }
.rel-card:hover .rc-open{ opacity:1; gap:10px; }

/* ---------- Library card essence line ---------- */
.paper-card .pc-essence{ font-size:14px; color:var(--ink-soft); line-height:1.55; margin-top:12px; }

/* ---------- Responsive ---------- */
@media (max-width: 940px){
  .doc-layout{ grid-template-columns:1fr; }
  .doc-aside{ position:static; flex-direction:row; flex-wrap:wrap; }
  .doc-aside .aside-card{ flex:1; min-width:260px; }
  .read-controls{ top:74px; }
}
@media (max-width: 560px){
  .lvl-seg{ min-width:0; }
  .lvl-seg button{ padding:8px 9px; }
  .lvl-seg button .t{ font-size:15px; }
  .doc-aside{ flex-direction:column; }
  .rc-lang span{ display:none; }
}