/* SE423 study pages (midterm cheat sheet). Tokens on :root, dark values under
   html[data-theme="dark"]; html-theme-sync.js sets data-theme. */

:root {
  --bg: #f6f5fb;
  --surface: #ffffff;
  --surface-2: #f1eff8;
  --surface-3: #e9e6f3;
  --border: #e1ddec;
  --text: #17152b;
  --dim: #5d5974;
  --faint: #8b87a3;
  --good: hsl(152 60% 32%);
  --good-soft: hsl(152 60% 40% / 0.11);
  --bad: hsl(352 68% 46%);
  --bad-soft: hsl(352 80% 55% / 0.1);
  --warn: hsl(28 88% 42%);
  --warn-soft: hsl(32 95% 52% / 0.12);
  --hue: 262;
  --lit: 48%;
  --shadow: 0 1px 2px rgba(30, 20, 70, 0.05), 0 8px 26px rgba(40, 25, 90, 0.06);
  --radius: 14px;
  --mono: "JetBrains Mono", ui-monospace, monospace;
  --serif: "Fraunces", Georgia, serif;
  --sans: "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;
  --pad: clamp(12px, 3vw, 44px);
  color-scheme: light;
}

html[data-theme="dark"] {
  --bg: #090b14;
  --surface: #121627;
  --surface-2: #0f1322;
  --surface-3: #1a2036;
  --border: #252c47;
  --text: #eceffb;
  --dim: #a0a8c6;
  --faint: #6f789a;
  --good: hsl(152 58% 60%);
  --good-soft: hsl(152 55% 50% / 0.14);
  --bad: hsl(352 85% 70%);
  --bad-soft: hsl(352 80% 60% / 0.14);
  --warn: hsl(36 95% 64%);
  --warn-soft: hsl(34 90% 55% / 0.14);
  --lit: 68%;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.5), 0 12px 32px rgba(0, 0, 0, 0.4);
  color-scheme: dark;
}

/* per-chapter accent; re-declared wherever --hue changes */
:root,
[style*="--hue"] {
  --accent: hsl(var(--hue) 72% var(--lit));
  --accent-soft: hsl(var(--hue) 85% var(--lit) / 0.11);
  --accent-line: hsl(var(--hue) 70% var(--lit) / 0.38);
  --accent-fill: hsl(var(--hue) 70% 42%);
}

/* html-theme-sync.js injects overflow-x:hidden, which breaks the sticky bar */
html:not(#se),
html:not(#se) body {
  overflow-x: clip;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 76px;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 15.5px/1.6 var(--sans);
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
}

.wrap {
  max-width: 1680px;
  margin: 0 auto;
  padding: 0 var(--pad);
}

/* ---------- top bar ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 30;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.topbar .wrap {
  display: flex;
  align-items: center;
  gap: 10px 18px;
  min-height: 58px;
  flex-wrap: wrap;
  padding-top: 8px;
  padding-bottom: 8px;
}

.brand {
  font-family: var(--mono);
  font-size: 12.5px;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--dim);
  white-space: nowrap;
}

.brand b {
  color: var(--text);
}

.topnav {
  display: flex;
  gap: 4px;
  flex-wrap: wrap;
}

.topnav a {
  font-size: 13.5px;
  font-weight: 600;
  text-decoration: none;
  color: var(--dim);
  padding: 6px 12px;
  border-radius: 999px;
}

.topnav a:hover,
.topnav a.on {
  color: var(--text);
  background: var(--surface-3);
}

.topbar-end {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 8px;
}

.btn {
  font: 600 13px/1 var(--sans);
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 9px 14px;
  cursor: pointer;
}

.btn:hover {
  border-color: var(--accent-line);
}

.btn.primary {
  background: var(--accent-fill);
  border-color: transparent;
  color: #fff;
}

.btn.primary:hover {
  filter: brightness(1.08);
}

.btn:focus-visible,
.chip:focus-visible,
.opt:focus-within,
textarea:focus-visible,
select:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* ---------- hero ---------- */
.hero {
  padding: clamp(22px, 4vw, 52px) 0 10px;
}

.eyebrow {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 600;
}

h1 {
  font-family: var(--serif);
  font-weight: 650;
  font-size: clamp(30px, 4.6vw, 54px);
  line-height: 1.05;
  margin: 8px 0 12px;
  letter-spacing: -0.01em;
}

.lede {
  color: var(--dim);
  font-size: clamp(15px, 1.3vw, 17.5px);
  margin: 0;
}

.scope {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 200px), 1fr));
  gap: 10px;
  margin: 22px 0 10px;
}

.scope a {
  display: block;
  text-decoration: none;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-top: 3px solid var(--accent);
  border-radius: 12px;
  padding: 12px 14px;
}

.scope a:hover {
  box-shadow: var(--shadow);
}

.scope .n {
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--accent);
  font-weight: 600;
  letter-spacing: 0.06em;
}

.scope .t {
  display: block;
  font-weight: 650;
  margin: 2px 0;
  line-height: 1.3;
}

.scope .m {
  font-size: 12.5px;
  color: var(--dim);
}

.steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 260px), 1fr));
  gap: 10px;
  margin: 16px 0 0;
  padding: 0;
  list-style: none;
  counter-reset: s;
}

.steps li {
  counter-increment: s;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px 14px 12px 46px;
  position: relative;
  font-size: 14.5px;
}

.steps li::before {
  content: counter(s);
  position: absolute;
  left: 14px;
  top: 12px;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--accent-fill);
  color: #fff;
  font: 700 12px/22px var(--mono);
  text-align: center;
}

/* ---------- sections ---------- */
.part {
  padding: 34px 0 8px;
}

.part-head {
  display: flex;
  align-items: baseline;
  gap: 12px;
  flex-wrap: wrap;
  border-bottom: 1px solid var(--border);
  padding-bottom: 10px;
  margin-bottom: 18px;
}

.part-head h2 {
  font-family: var(--serif);
  font-size: clamp(24px, 3vw, 36px);
  margin: 0;
  line-height: 1.1;
}

.part-head p {
  margin: 0;
  color: var(--dim);
}

.chapter {
  margin: 0 0 34px;
}

.ch-head {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  margin: 0 0 14px;
}

.ch-badge {
  font: 700 12.5px/1 var(--mono);
  color: #fff;
  background: var(--accent-fill);
  padding: 7px 10px;
  border-radius: 8px;
  letter-spacing: 0.04em;
}

.ch-head h3 {
  margin: 0;
  font-size: clamp(19px, 2vw, 25px);
  line-height: 1.2;
}

.ch-head .meta {
  font-size: 13px;
  color: var(--dim);
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 330px), 1fr));
  gap: 14px;
  align-items: start;
}

.grid.wide {
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 460px), 1fr));
}

.span-all {
  grid-column: 1 / -1;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 18px;
  box-shadow: var(--shadow);
  min-width: 0;
}

.card h4 {
  margin: 0 0 8px;
  font-size: 15.5px;
  line-height: 1.3;
  display: flex;
  gap: 8px;
  align-items: baseline;
}

.card h4 .k {
  font: 700 11px/1 var(--mono);
  color: var(--accent);
  background: var(--accent-soft);
  padding: 4px 6px;
  border-radius: 6px;
  white-space: nowrap;
}

.card p {
  margin: 0 0 8px;
}

.card p:last-child,
.card ul:last-child,
.card ol:last-child {
  margin-bottom: 0;
}

.card ul,
.card ol {
  margin: 0 0 8px;
  padding-left: 20px;
}

.card li {
  margin: 2px 0;
}

.card li::marker {
  color: var(--accent);
}

.cols-2 {
  columns: 2 180px;
  column-gap: 22px;
}

.cols-2 li {
  break-inside: avoid;
}

dl.defs {
  margin: 0;
  display: grid;
  gap: 10px;
}

dl.defs div {
  border-left: 3px solid var(--accent-line);
  padding-left: 10px;
}

dl.defs dt {
  font-weight: 700;
}

dl.defs dd {
  margin: 0;
  color: var(--dim);
}

.term {
  font-weight: 700;
  color: var(--text);
}

mark.kw {
  background: var(--accent-soft);
  color: inherit;
  border-radius: 4px;
  padding: 0 3px;
  font-weight: 600;
}

/* callouts */
.hook,
.trap,
.tip {
  border-radius: 12px;
  padding: 10px 12px;
  margin: 10px 0 0;
  font-size: 14.5px;
}

.hook {
  background: var(--accent-soft);
  border: 1px dashed var(--accent-line);
}

.trap {
  background: var(--bad-soft);
  border: 1px solid color-mix(in srgb, var(--bad) 30%, transparent);
}

.tip {
  background: var(--good-soft);
  border: 1px solid color-mix(in srgb, var(--good) 30%, transparent);
}

.hook b:first-child,
.trap b:first-child,
.tip b:first-child {
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-right: 6px;
}

.hook b:first-child {
  color: var(--accent);
}

.trap b:first-child {
  color: var(--bad);
}

.tip b:first-child {
  color: var(--good);
}

/* flow chips */
.flow {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  margin: 6px 0;
}

.flow span {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 4px 9px;
  font-size: 13.5px;
  font-weight: 600;
}

.flow i {
  font-style: normal;
  color: var(--accent);
  font-weight: 700;
}

/* pyramid */
.pyramid {
  display: grid;
  gap: 4px;
  justify-items: center;
  margin: 6px 0;
}

.pyramid div {
  background: var(--accent-soft);
  border: 1px solid var(--accent-line);
  border-radius: 6px;
  text-align: center;
  font-size: 13.5px;
  font-weight: 600;
  padding: 4px 8px;
}

.pyramid div:nth-child(1) {
  width: 46%;
}
.pyramid div:nth-child(2) {
  width: 60%;
}
.pyramid div:nth-child(3) {
  width: 74%;
}
.pyramid div:nth-child(4) {
  width: 88%;
}
.pyramid div:nth-child(5) {
  width: 100%;
}

.pyramids {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 220px), 1fr));
  gap: 14px;
}

.pyramids small {
  display: block;
  text-align: center;
  color: var(--dim);
  font-size: 12.5px;
  margin-top: 4px;
}

/* tables */
.tbl {
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface);
}

.tbl .sg-table-scroll {
  overflow: visible;
}

.tbl .sg-table-scroll > table,
.tbl table {
  min-width: 0;
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}

.tbl th,
.tbl td {
  text-align: left;
  vertical-align: top;
  padding: 8px 12px;
  border-bottom: 1px solid var(--border);
}

.tbl th {
  background: var(--surface-2);
  font-size: 12.5px;
  font-family: var(--mono);
  letter-spacing: 0.04em;
  color: var(--dim);
}

.tbl tr:last-child td {
  border-bottom: 0;
}

.tbl td:first-child {
  font-weight: 650;
}

.card .tbl {
  margin: 4px 0 0;
}

/* lists to memorize */
.mem {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 300px), 1fr));
  gap: 12px;
  align-items: start;
}

.mem .card h4 .count {
  margin-left: auto;
  font: 700 12px/1 var(--mono);
  color: var(--accent);
}

.mnemo {
  font-family: var(--mono);
  font-size: 13px;
  color: var(--accent);
  font-weight: 600;
  margin: 0 0 6px;
}

.mem-filter {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 0 0 14px;
}

.chip {
  font: 600 13px/1 var(--sans);
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--dim);
  border-radius: 999px;
  padding: 8px 12px;
  cursor: pointer;
}

.chip[aria-pressed="true"] {
  background: var(--accent-fill);
  border-color: transparent;
  color: #fff;
}

.cover .card ol,
.cover .card ul {
  filter: blur(5px);
  user-select: none;
  transition: filter 0.2s;
}

.cover .card.peek ol,
.cover .card.peek ul,
.cover .card:focus-within ol {
  filter: none;
}

.cover .card {
  cursor: pointer;
}

/* ---------- practice ---------- */
.score {
  display: grid;
  grid-template-columns: minmax(180px, 260px) 1fr;
  gap: 18px;
  align-items: center;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 18px;
  box-shadow: var(--shadow);
  margin: 0 0 14px;
}

.score .big {
  font-family: var(--serif);
  font-size: clamp(34px, 4vw, 48px);
  font-weight: 650;
  line-height: 1;
}

.score .big small {
  font-size: 0.45em;
  color: var(--dim);
  font-family: var(--sans);
  font-weight: 600;
}

.score .sub {
  color: var(--dim);
  font-size: 13px;
  margin-top: 6px;
}

.bars {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 170px), 1fr));
  gap: 10px 14px;
}

.bar .lbl {
  display: flex;
  justify-content: space-between;
  font-size: 12.5px;
  font-weight: 600;
  gap: 8px;
}

.bar .lbl span:last-child {
  font-family: var(--mono);
  color: var(--dim);
}

.bar .track {
  height: 8px;
  border-radius: 99px;
  background: var(--surface-3);
  overflow: hidden;
  margin-top: 4px;
}

.bar .fill {
  height: 100%;
  width: 0;
  background: var(--accent-fill);
  border-radius: 99px;
  transition: width 0.35s;
}

.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 16px;
  align-items: center;
  margin: 0 0 14px;
}

.toolbar .group {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  align-items: center;
}

.toolbar .group > span {
  font: 600 11.5px/1 var(--mono);
  letter-spacing: 0.08em;
  color: var(--faint);
  text-transform: uppercase;
  margin-right: 2px;
}

.toolbar .actions {
  margin-left: auto;
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.qlist {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 520px), 1fr));
  gap: 14px;
  align-items: start;
}

.q {
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  border-radius: var(--radius);
  padding: 14px 16px;
  box-shadow: var(--shadow);
  min-width: 0;
}

.q.ok {
  border-left-color: var(--good);
}

.q.part-ok {
  border-left-color: var(--warn);
}

.q.no {
  border-left-color: var(--bad);
}

.q-top {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  align-items: center;
  margin-bottom: 6px;
}

.tag {
  font: 700 10.5px/1 var(--mono);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 4px 7px;
  border-radius: 6px;
  background: var(--surface-3);
  color: var(--dim);
}

.tag.ch {
  background: var(--accent-soft);
  color: var(--accent);
}

.q-top .pts {
  margin-left: auto;
  font: 600 12px/1 var(--mono);
  color: var(--dim);
}

.q-text {
  font-weight: 600;
  margin: 0 0 10px;
  line-height: 1.45;
}

.opts {
  display: grid;
  gap: 6px;
}

.opt {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 8px 10px;
  cursor: pointer;
  background: var(--surface-2);
}

.opt input {
  margin: 3px 0 0;
  accent-color: var(--accent-fill);
}

.opt.right {
  border-color: var(--good);
  background: var(--good-soft);
}

.opt.wrong {
  border-color: var(--bad);
  background: var(--bad-soft);
}

.tf {
  grid-template-columns: 1fr 1fr;
}

.match {
  display: grid;
  gap: 6px;
}

.match .row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.4fr);
  gap: 8px;
  align-items: center;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 6px 8px;
  background: var(--surface-2);
}

.match .row.right {
  border-color: var(--good);
  background: var(--good-soft);
}

.match .row.wrong {
  border-color: var(--bad);
  background: var(--bad-soft);
}

.match .row > span {
  font-weight: 600;
  font-size: 14px;
}

select,
textarea {
  font: 14px/1.45 var(--sans);
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  width: 100%;
  min-width: 0;
}

select {
  padding: 7px 8px;
}

textarea {
  padding: 9px 10px;
  min-height: 92px;
  resize: vertical;
}

.q-actions {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: 10px;
}

.feedback {
  margin-top: 10px;
  font-size: 14px;
  border-radius: 10px;
  padding: 10px 12px;
  background: var(--surface-2);
  border: 1px solid var(--border);
}

.feedback[hidden] {
  display: none;
}

.feedback .verdict {
  font-weight: 700;
  margin-bottom: 4px;
}

.feedback .verdict.ok {
  color: var(--good);
}

.feedback .verdict.no {
  color: var(--bad);
}

.feedback .verdict.part {
  color: var(--warn);
}

.kwlist {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  margin: 6px 0;
  padding: 0;
  list-style: none;
}

.kwlist li {
  font-size: 12.5px;
  font-weight: 600;
  border-radius: 6px;
  padding: 3px 7px;
  border: 1px solid var(--border);
}

.kwlist li.hit {
  color: var(--good);
  background: var(--good-soft);
  border-color: color-mix(in srgb, var(--good) 35%, transparent);
}

.kwlist li.miss {
  color: var(--bad);
  background: var(--bad-soft);
  border-color: color-mix(in srgb, var(--bad) 35%, transparent);
}

.why {
  color: var(--dim);
  margin-top: 4px;
}

.empty {
  color: var(--dim);
  padding: 20px;
  text-align: center;
  border: 1px dashed var(--border);
  border-radius: var(--radius);
}

.foot {
  color: var(--faint);
  font-size: 13px;
  padding: 30px 0 40px;
  text-align: center;
}

/* phones: tables become labelled blocks, tighter cards */
@media (max-width: 640px) {
  :root {
    --pad: 8px;
  }

  body {
    font-size: 15px;
  }

  .topbar .wrap {
    gap: 6px 10px;
    min-height: 0;
  }

  .topnav a {
    padding: 6px 9px;
    font-size: 13px;
  }

  .brand {
    display: none;
  }

  .topbar-end {
    margin-left: auto;
  }

  .card,
  .q {
    padding: 12px 11px;
  }

  .tbl thead {
    display: none;
  }

  .tbl tr {
    display: block;
    border-bottom: 1px solid var(--border);
    padding: 6px 0;
  }

  .tbl tr:last-child {
    border-bottom: 0;
  }

  .tbl td {
    display: block;
    border: 0;
    padding: 3px 10px;
  }

  .tbl td[data-label]::before {
    content: attr(data-label);
    display: block;
    font: 600 11px/1.4 var(--mono);
    letter-spacing: 0.05em;
    color: var(--faint);
    text-transform: uppercase;
  }

  .score {
    grid-template-columns: 1fr;
  }

  .match .row {
    grid-template-columns: 1fr;
  }

  .toolbar .actions {
    margin-left: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  .bar .fill,
  .cover .card ol,
  .cover .card ul {
    transition: none;
  }
}

@media print {
  .topbar,
  #practice,
  .mem-filter {
    display: none;
  }
  .cover .card ol,
  .cover .card ul {
    filter: none;
  }
  .card,
  .q {
    box-shadow: none;
    break-inside: avoid;
  }
}