/* =========================================================================
   Custom Worksheet — print-first exam-paper stylesheet
   Three serif directions selectable via .theme-a / .theme-b / .theme-c
   ========================================================================= */

/* ---- Page geometry --------------------------------------------------- */
@page {
  size: A4;
  margin: 0;          /* each .page div carries its own margins as padding */
}

:root {
  --paper: #ffffff;
  --ink: #161514;
  --ink-soft: #3a3835;
  --muted: #6f6b65;
  --faint: #b9b4ac;          /* answer ruling */
  --hair: #2a2825;           /* structural hairlines */
  --hair-soft: #d8d3ca;
}

/* ---- Screen scaffold ------------------------------------------------- */
* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: #6c6963;
  color: var(--ink);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.sheet-wrap {
  padding: 92px 24px 64px;
  display: flex;
  justify-content: center;
}

/* .worksheet is now just the themed wrapper; pages are generated by JS */
.worksheet {
  counter-reset: none;
  font-feature-settings: "onum" 1, "liga" 1;
  font-variant-numeric: oldstyle-nums;
}

#flow { display: none; }                 /* authored source, hidden after pagination */

.pages {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 22px;
}
.page {
  position: relative;
  width: 210mm;
  height: 297mm;
  background: var(--paper);
  padding: 15mm 15mm 14mm 15mm;
  box-shadow: 0 1px 0 rgba(0,0,0,.04), 0 18px 50px rgba(0,0,0,.34);
  overflow: hidden;
}
.page-inner {
  height: calc(297mm - 15mm - 14mm);
}
.page-inner > :first-child { margin-top: 0 !important; }
.page-foot {
  position: absolute;
  left: 15mm; right: 15mm; bottom: 6mm;
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  font-size: 8.5pt;
  letter-spacing: .04em;
  color: var(--muted);
  border-top: 0.6pt solid var(--hair-soft);
  padding-top: 2mm;
  font-variant-numeric: lining-nums;
}

/* =========================================================================
   THEME TOKENS
   ========================================================================= */
.theme-a {            /* Classic — Times-like, pure black, centred title */
  --font-body: "Tinos", "Times New Roman", serif;
  --font-display: "Tinos", "Times New Roman", serif;
  --accent: #161514;
  --rule-strong: #1d1b19;
  --num-color: #161514;
  --base-size: 11.6pt;
  --lead: 1.5;
  --title-align: center;
}
.theme-b {            /* Structured — Source Serif, boxed marks, gutter rule */
  --font-body: "Source Serif 4", Georgia, serif;
  --font-display: "Source Serif 4", Georgia, serif;
  --accent: #1f2a44;
  --rule-strong: #243044;
  --num-color: #1f2a44;
  --base-size: 11.4pt;
  --lead: 1.55;
  --title-align: left;
}
.theme-c {            /* Editorial — Spectral, single maroon ink accent */
  --font-body: "Spectral", Georgia, serif;
  --font-display: "Spectral", Georgia, serif;
  --accent: #7a1d2b;
  --rule-strong: #7a1d2b;
  --num-color: #7a1d2b;
  --base-size: 11.8pt;
  --lead: 1.6;
  --title-align: left;
}

.worksheet {
  font-family: var(--font-body);
  font-size: var(--base-size);
  line-height: var(--lead);
  color: var(--ink);
}

/* =========================================================================
   MASTHEAD
   ========================================================================= */
.ws-head {
  text-align: var(--title-align);
  padding-bottom: 7mm;
  margin-bottom: 8mm;
  border-bottom: 1.4pt solid var(--rule-strong);
  position: relative;
}
.theme-a .ws-head { border-bottom-style: double; border-bottom-width: 3pt; }

.ws-course {
  font-size: 9.5pt;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--muted);
  font-variant-numeric: lining-nums;
  margin: 0 0 5mm;
}
.theme-c .ws-course { color: var(--accent); }

.ws-title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 27pt;
  line-height: 1.05;
  letter-spacing: -0.01em;
  margin: 0;
}
.theme-c .ws-title { font-size: 31pt; font-weight: 800; }
.theme-a .ws-title { letter-spacing: 0; }

.ws-sub {
  margin: 4mm 0 0;
  font-size: 11pt;
  color: var(--ink-soft);
}

/* marks tally chip in the masthead */
.ws-meta {
  display: flex;
  gap: 0;
  justify-content: var(--title-align);
  margin-top: 6mm;
  font-variant-numeric: lining-nums;
}
.theme-a .ws-meta { justify-content: center; }
.ws-meta-row {
  display: flex;
  gap: 9mm;
  align-items: baseline;
  font-size: 10pt;
  color: var(--muted);
  letter-spacing: .02em;
}
.ws-meta-row b {
  color: var(--ink);
  font-size: 12.5pt;
  font-weight: 700;
  font-variant-numeric: lining-nums;
}
.ws-meta-row .sep { color: var(--hair-soft); }

/* =========================================================================
   LESSON BLOCK
   ========================================================================= */
.lesson { margin: 0 0 2mm; }
.lesson + .lesson { margin-top: 9mm; }

.lesson-head {
  break-after: avoid;
  page-break-after: avoid;
  margin: 8mm 0 5mm;
  padding-bottom: 2.5mm;
  border-bottom: 0.6pt solid var(--hair-soft);
  display: flex;
  align-items: baseline;
  gap: 3.5mm;
}
.lesson-kicker {
  font-size: 9pt;
  letter-spacing: .15em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 700;
  white-space: nowrap;
  font-variant-numeric: lining-nums;
}
.lesson-name {
  font-family: var(--font-display);
  font-size: 13.5pt;
  font-weight: 600;
  margin: 0;
  color: var(--ink);
}
.theme-b .lesson-head { border-bottom-color: var(--accent); border-bottom-width: 0.9pt; }
.theme-c .lesson-head { border-bottom: none; }
.theme-c .lesson-kicker::after {
  content: "";
  display: inline-block;
  width: 14mm; height: 0;
  border-top: 1pt solid var(--accent);
  margin-left: 3mm;
  vertical-align: middle;
}

/* question-group sub-heading: "1. Short-answer questions" */
.qgroup { margin-top: 4mm; }
.qgroup-head {
  break-after: avoid;
  page-break-after: avoid;
  display: flex;
  align-items: baseline;
  gap: 2.5mm;
  margin: 5mm 0 3mm;
  font-family: var(--font-display);
  font-size: 11.5pt;
  font-weight: 700;
  color: var(--ink-soft);
}
.qgroup-head .qg-num {
  font-variant-numeric: lining-nums;
  color: var(--accent);
}
.qgroup-head .qg-name { font-weight: 600; }

/* =========================================================================
   QUESTION ROW  — gutter | body | marks rail
   ========================================================================= */
.q {
  display: grid;
  grid-template-columns: 11mm 1fr 19mm;
  column-gap: 4mm;
  align-items: start;
  margin: 0 0 6mm;
  break-inside: avoid;
  page-break-inside: avoid;
}
/* allow the big extended-response items to break if they must */
.q.q-long { break-inside: auto; page-break-inside: auto; }

.q-num {
  grid-column: 1;
  font-weight: 700;
  font-size: 12pt;
  color: var(--num-color);
  font-variant-numeric: lining-nums;
  text-align: right;
  padding-top: 0.3mm;
  letter-spacing: -0.01em;
}
.theme-b .q-num {
  text-align: left;
}

.q-body { grid-column: 2; min-width: 0; }
.q-body > p { margin: 0 0 2mm; }
.q-body > p:first-child { margin-top: 0; }
.q-stem { text-wrap: pretty; }

/* parts list (a)(b)(c) */
ol.parts {
  list-style: none;
  margin: 2.5mm 0 0;
  padding: 0;
  counter-reset: part;
}
ol.parts > li {
  counter-increment: part;
  position: relative;
  padding-left: 9mm;
  margin: 0 0 2mm;
  text-wrap: pretty;
}
ol.parts > li::before {
  content: "(" counter(part, lower-alpha) ")";
  position: absolute;
  left: 0;
  top: 0;
  font-variant-numeric: lining-nums;
  color: var(--ink-soft);
}

/* marks rail */
.q-marks {
  grid-column: 3;
  text-align: right;
  padding-top: 0.6mm;
  line-height: 1.15;
}
.q-marks .m {
  font-weight: 700;
  font-size: 12.5pt;
  font-variant-numeric: lining-nums;
  color: var(--ink);
  display: inline-block;
}
.q-marks .m-label {
  display: block;
  font-size: 7.5pt;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--muted);
  margin-top: 0.2mm;
}
.q-marks .band {
  display: block;
  margin-top: 1.6mm;
  font-size: 8.5pt;
  font-style: italic;
  color: var(--muted);
  font-variant-numeric: lining-nums;
}
/* Theme B: boxed marks */
.theme-b .q-marks {
  border: 0.8pt solid var(--hair-soft);
  border-radius: 1pt;
  padding: 1.4mm 1.8mm 1.8mm;
}
.theme-b .q-marks .band {
  margin-top: 1.4mm;
  padding-top: 1.4mm;
  border-top: 0.5pt solid var(--hair-soft);
}
/* Theme C: small-caps accent marks, no box */
.theme-c .q-marks .m { color: var(--accent); }
.theme-c .q-marks .m-label { color: var(--accent); opacity: .8; }

/* =========================================================================
   ANSWER SPACE  (ruled lines / sketch grid)  — toggled by .show-space
   ========================================================================= */
.answer { display: none; }
.show-space .answer { display: block; }

.answer.ruled {
  margin-top: 3mm;
  height: calc(var(--lines, 5) * 8.5mm);
  background-image: repeating-linear-gradient(
    to bottom,
    transparent 0,
    transparent calc(8.5mm - 0.4pt),
    var(--faint) calc(8.5mm - 0.4pt),
    var(--faint) 8.5mm
  );
}

.answer.grid {
  margin-top: 3mm;
  height: var(--box, 70mm);
  border: 0.6pt solid var(--hair-soft);
  background-image:
    repeating-linear-gradient(to bottom, transparent 0, transparent calc(5mm - 0.3pt), #e7e3db calc(5mm - 0.3pt), #e7e3db 5mm),
    repeating-linear-gradient(to right,  transparent 0, transparent calc(5mm - 0.3pt), #e7e3db calc(5mm - 0.3pt), #e7e3db 5mm);
}
.answer .answer-tag {
  display: block;
  font-size: 8pt;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 1.5mm;
}

/* =========================================================================
   ANSWER KEY  — its own page, toggled by .show-key
   ========================================================================= */
.answer-key { display: none; }
.show-key .answer-key {
  display: block;
  break-before: page;
  page-break-before: always;
}
.key-head {
  border-bottom: 1.4pt solid var(--rule-strong);
  padding-bottom: 5mm;
  margin-bottom: 7mm;
}
.theme-a .key-head { border-bottom-style: double; border-bottom-width: 3pt; }
.key-head .ws-course { margin-bottom: 3mm; }
.key-title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 22pt;
  margin: 0;
}
.key-entry {
  break-inside: avoid;
  page-break-inside: avoid;
  margin: 0 0 6mm;
  padding-left: 11mm;
  position: relative;
}
.key-ref {
  position: absolute;
  left: 0; top: 0.2mm;
  font-weight: 700;
  font-size: 10.5pt;
  color: var(--num-color);
  font-variant-numeric: lining-nums;
}
.key-lesson {
  font-size: 8.5pt;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 1.5mm;
}
.key-q {
  font-size: 10.5pt;
  line-height: 1.45;
  color: var(--ink-soft);
}
.key-q .key-answer { margin: 0 0 1mm; }
.key-q .key-answer b { color: var(--ink); font-weight: 700; }

.crit-part {
  margin: 2.5mm 0 0;
}
.crit-part .crit-head {
  font-weight: 700;
  font-size: 9.5pt;
  color: var(--ink);
}
.crit-part ul {
  margin: 1mm 0 0;
  padding-left: 5mm;
  list-style: none;
}
.crit-part ul li {
  position: relative;
  padding-left: 0;
  margin: 0.8mm 0;
  font-size: 10pt;
}
.crit-part ul li::before {
  content: "";
  position: absolute;
  left: -4mm; top: 2.2mm;
  width: 1.6mm; height: 1.6mm;
  background: var(--accent);
  border-radius: 50%;
}
.crit-mark { font-weight: 700; color: var(--accent); font-variant-numeric: lining-nums; }

/* =========================================================================
   FOOTER
   ========================================================================= */
.ws-foot {
  margin-top: 11mm;
  padding-top: 3mm;
  border-top: 0.6pt solid var(--hair-soft);
  font-size: 8.5pt;
  letter-spacing: .04em;
  color: var(--muted);
  display: flex;
  justify-content: space-between;
  font-variant-numeric: lining-nums;
}

/* KaTeX sizing so inline maths matches body weight, not oversized */
.katex { font-size: 1.04em; }
.katex-display { margin: 2mm 0; }

/* =========================================================================
   TOOLBAR  (screen only)
   ========================================================================= */
.toolbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 56px;
  z-index: 50;
  background: #232220;
  color: #ece8e1;
  display: flex;
  align-items: center;
  gap: 22px;
  padding: 0 20px;
  font-family: "Source Serif 4", Georgia, serif;
  box-shadow: 0 1px 0 rgba(0,0,0,.5);
}
.tb-brand {
  font-weight: 700;
  font-size: 14px;
  letter-spacing: .02em;
  color: #fff;
  margin-right: 4px;
}
.tb-brand small { display:block; font-weight:400; font-size:10.5px; color:#9a948a; letter-spacing:.06em; }
.tb-group { display: flex; align-items: center; gap: 10px; }
.tb-label { font-size: 11px; text-transform: uppercase; letter-spacing: .12em; color: #9a948a; }

.seg { display: inline-flex; border: 1px solid #4a4843; border-radius: 6px; overflow: hidden; }
.seg button {
  font-family: inherit;
  font-size: 12.5px;
  padding: 7px 13px;
  background: transparent;
  color: #cfc9c0;
  border: none;
  border-right: 1px solid #4a4843;
  cursor: pointer;
  transition: background .12s, color .12s;
}
.seg button:last-child { border-right: none; }
.seg button:hover { background: #34322e; }
.seg button.active { background: #efe9df; color: #232220; font-weight: 600; }

.tgl { display: inline-flex; align-items: center; gap: 8px; cursor: pointer; -webkit-user-select: none; user-select: none; font-size: 13px; color: #d7d2c9; }
.tgl input { display: none; }
.tgl .track {
  width: 36px; height: 20px; border-radius: 20px; background: #4a4843;
  position: relative; transition: background .15s;
}
.tgl .track::after {
  content: ""; position: absolute; top: 2px; left: 2px;
  width: 16px; height: 16px; border-radius: 50%; background: #cfc9c0;
  transition: transform .15s, background .15s;
}
.tgl input:checked + .track { background: #b7935a; }
.tgl input:checked + .track::after { transform: translateX(16px); background: #fff; }

.tb-spacer { flex: 1; }
.tb-print {
  font-family: inherit;
  font-size: 13px;
  font-weight: 600;
  padding: 8px 16px;
  border-radius: 6px;
  border: none;
  background: #efe9df;
  color: #232220;
  cursor: pointer;
}
.tb-print:hover { background: #fff; }

/* =========================================================================
   PRINT
   ========================================================================= */
@media print {
  html, body { background: #fff; }
  .toolbar { display: none !important; }
  .sheet-wrap { padding: 0; display: block; }
  .pages { gap: 0; display: block; }
  .page {
    box-shadow: none;
    margin: 0;
    page-break-after: always;
    break-after: page;
  }
  .page:last-child { page-break-after: auto; break-after: auto; }
  .answer.ruled,
  .answer.grid { background-color: #fff; }
}

/* responsive: scale the page down on small screens */
@media (max-width: 880px) {
  .sheet-wrap { padding: 70px 0 32px; overflow-x: auto; }
  .toolbar { gap: 12px; overflow-x: auto; }
}