:root {
  color-scheme: light;
  --ink: #1d1d1f;
  --muted: #6e6e73;
  --soft: #f5f5f7;
  --soft-2: #fbfbfd;
  --paper: #ffffff;
  --line: rgba(0, 0, 0, 0.1);
  --line-strong: rgba(0, 0, 0, 0.16);
  --blue: #0071e3;
  --blue-dark: #005bb5;
  --green: #2f7d68;
  --red: #c94f3d;
  --yellow: #a66d00;
  --purple: #6f5bd7;
  --shadow: 0 18px 48px rgba(0, 0, 0, 0.08);
  --shadow-strong: 0 30px 90px rgba(0, 0, 0, 0.14);
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "SF Pro Text",
    "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  background: var(--soft);
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--soft);
  letter-spacing: 0;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

button,
a {
  -webkit-tap-highlight-color: transparent;
}

button {
  letter-spacing: 0;
}

h1,
h2,
h3,
p {
  overflow-wrap: anywhere;
}

h1,
h2,
h3 {
  margin: 0;
  color: var(--ink);
  line-height: 1.06;
}

p {
  margin: 0;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 22px;
  min-height: 52px;
  padding: 8px clamp(18px, 4vw, 54px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.08);
  background: rgba(251, 251, 253, 0.78);
  backdrop-filter: saturate(180%) blur(22px);
  -webkit-backdrop-filter: saturate(180%) blur(22px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 30px;
  height: 30px;
  flex: 0 0 auto;
  color: #fff;
  border-radius: 8px;
  background: #1d1d1f;
  box-shadow: 0 8px 22px rgba(0, 0, 0, 0.14);
}

.brand-moon {
  width: 19px;
  height: 19px;
  fill: none;
  stroke: #fff;
  stroke-width: 2.15;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.brand strong,
.brand small {
  display: block;
  white-space: nowrap;
}

.brand strong {
  font-size: 14px;
  font-weight: 720;
}

.brand small {
  margin-top: 1px;
  color: var(--muted);
  font-size: 11px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 2px;
  overflow-x: auto;
  scrollbar-width: none;
}

.nav-links::-webkit-scrollbar {
  display: none;
}

.nav-links a {
  display: inline-flex;
  align-items: center;
  min-height: 32px;
  padding: 0 10px;
  color: #424245;
  font-size: 12px;
  font-weight: 520;
  white-space: nowrap;
  border-radius: 999px;
}

.nav-links a:hover,
.nav-links a:focus-visible {
  color: #000;
  background: rgba(0, 0, 0, 0.05);
  outline: none;
}

.section {
  width: min(1120px, calc(100% - 44px));
  margin: 0 auto;
}

.hero {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  min-height: clamp(650px, 84vh, 820px);
  overflow: hidden;
  background:
    radial-gradient(circle at 50% 98%, rgba(0, 113, 227, 0.12), transparent 28%),
    linear-gradient(180deg, #fff 0%, #f7f7f9 42%, #ececf0 100%);
  isolation: isolate;
}

.hero-visual {
  position: relative;
  z-index: 1;
  order: 2;
  width: min(700px, calc(100% - 64px));
  margin: 38px auto 52px;
  padding: 14px;
  overflow: hidden;
  border-radius: 42px;
  background: rgba(255, 255, 255, 0.9);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.86),
    0 46px 110px rgba(0, 0, 0, 0.16);
}

.hero-bg {
  display: block;
  width: 100%;
  aspect-ratio: 1800 / 1180;
  object-fit: cover;
  border-radius: 30px;
  filter: saturate(0.78) contrast(1.06) brightness(1.06);
  opacity: 0.86;
}

.hero-inner {
  position: relative;
  z-index: 2;
  order: 1;
  width: min(980px, calc(100% - 44px));
  margin: 0 auto;
  padding: clamp(82px, 11vh, 118px) 0 0;
  text-align: center;
}

.eyebrow,
.section-kicker {
  margin: 0;
  color: #86868b;
  font-size: 14px;
  font-weight: 650;
  letter-spacing: 0;
}

.hero .eyebrow {
  color: #6e6e73;
  font-size: 17px;
}

.hero h1 {
  max-width: 900px;
  margin: 14px auto 0;
  font-size: clamp(48px, 7vw, 92px);
  font-weight: 760;
  letter-spacing: 0;
}

.hero-copy {
  max-width: 760px;
  margin: 24px auto 0;
  color: var(--muted);
  font-size: clamp(19px, 2.1vw, 25px);
  font-weight: 430;
  line-height: 1.55;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 14px;
  margin-top: 34px;
}

.primary-action,
.secondary-action {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 42px;
  padding: 0 20px;
  font-size: 16px;
  font-weight: 560;
  border-radius: 999px;
  transition:
    transform 160ms ease,
    background 160ms ease,
    color 160ms ease;
}

.primary-action {
  color: #fff;
  background: var(--blue);
}

.primary-action:hover,
.primary-action:focus-visible {
  background: var(--blue-dark);
  outline: none;
  transform: translateY(-1px);
}

.secondary-action {
  color: var(--blue);
  background: rgba(0, 113, 227, 0.08);
}

.secondary-action:hover,
.secondary-action:focus-visible {
  color: #fff;
  background: var(--blue);
  outline: none;
  transform: translateY(-1px);
}

.intro-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(320px, 0.8fr);
  gap: 18px;
  padding: 28px 0 68px;
  align-items: stretch;
}

.signal-panel,
.metrics-strip a,
.template-card,
.method-card,
.flow article,
.boundary-card,
.signal-list div {
  border: 1px solid rgba(0, 0, 0, 0.06);
  border-radius: 28px;
  background: rgba(255, 255, 255, 0.86);
  box-shadow: var(--shadow);
}

.signal-panel {
  display: grid;
  align-content: center;
  min-height: 330px;
  padding: clamp(30px, 5vw, 56px);
}

.signal-panel h2,
.section-heading h2,
.question-heading h2,
.method-heading h2,
.behavior-copy h2,
.boundary-section h2 {
  margin-top: 12px;
  font-size: clamp(34px, 4.6vw, 60px);
  font-weight: 760;
}

.signal-panel p,
.section-heading p,
.question-heading p,
.method-heading p,
.behavior-copy p {
  margin-top: 18px;
  color: var(--muted);
  font-size: clamp(16px, 1.55vw, 19px);
  line-height: 1.72;
}

.reader-path {
  display: grid;
  gap: 0;
  margin: 26px 0 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line);
}

.reader-path li {
  display: grid;
  grid-template-columns: 112px minmax(0, 1fr);
  gap: 18px;
  padding: 18px 0;
  border-bottom: 1px solid var(--line);
}

.reader-path strong {
  color: var(--ink);
  font-size: 15px;
  font-weight: 760;
}

.reader-path span {
  color: var(--muted);
  font-size: 15px;
  line-height: 1.62;
}

.metrics-strip {
  display: grid;
  gap: 14px;
}

.metrics-strip a {
  display: grid;
  align-content: center;
  min-height: 116px;
  padding: 24px 26px;
  background: #fff;
  transition:
    transform 160ms ease,
    box-shadow 160ms ease,
    border-color 160ms ease;
}

.metrics-strip a:hover,
.metrics-strip a:focus-visible {
  border-color: rgba(0, 113, 227, 0.28);
  box-shadow: 0 24px 58px rgba(0, 0, 0, 0.12);
  outline: none;
  transform: translateY(-2px);
}

.metrics-strip strong {
  color: var(--ink);
  font-size: 20px;
  font-weight: 730;
  line-height: 1.25;
}

.metrics-strip span {
  margin-top: 10px;
  color: var(--muted);
  font-size: 15px;
  line-height: 1.56;
}

.section-heading {
  max-width: 780px;
  padding: 72px 0 30px;
}

.template-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
  padding-bottom: 78px;
}

.question-library-hero {
  padding: clamp(72px, 10vw, 124px) 0 clamp(38px, 6vw, 72px);
  background:
    linear-gradient(180deg, #fff 0%, rgba(245, 245, 247, 0.98) 100%);
}

.question-library-inner {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
}

.question-library-inner h1 {
  max-width: 800px;
  margin-top: 14px;
  font-size: clamp(46px, 7vw, 82px);
  font-weight: 760;
  letter-spacing: 0;
}

.question-library-inner p {
  max-width: 760px;
  margin-top: 22px;
  color: var(--muted);
  font-size: clamp(18px, 2vw, 23px);
  line-height: 1.62;
}

.question-studio {
  padding: 86px 0 92px;
  background: #fff;
}

.question-library {
  padding-top: 72px;
}

.question-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 34px;
}

.question-heading p {
  max-width: 490px;
}

.question-stack {
  display: grid;
  gap: 26px;
  margin-top: 38px;
}

.question-browser {
  margin-top: 36px;
}

.question-browser .question-stack {
  margin-top: 24px;
}

.question-toolbar {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, 380px);
  align-items: end;
  gap: 18px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 26px;
  background: rgba(245, 245, 247, 0.86);
}

.question-count {
  color: var(--ink);
  font-size: clamp(20px, 2vw, 27px);
  font-weight: 730;
  line-height: 1.2;
}

.question-updated {
  margin-top: 6px;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.45;
}

.question-search {
  display: grid;
  gap: 8px;
  color: #55555a;
  font-size: 12px;
  font-weight: 650;
}

.question-search input {
  width: 100%;
  min-height: 44px;
  padding: 0 14px;
  color: var(--ink);
  font: inherit;
  font-size: 15px;
  border: 1px solid var(--line-strong);
  border-radius: 14px;
  outline: none;
  background: #fff;
}

.question-search input:focus {
  border-color: var(--blue);
  box-shadow: 0 0 0 4px rgba(0, 113, 227, 0.12);
}

.question-case {
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 26px;
  background: #fff;
  box-shadow: var(--shadow-strong);
}

.question-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
}

.question-paper,
.analysis-panel {
  min-width: 0;
  padding: clamp(26px, 3vw, 38px);
}

.question-paper {
  color: var(--ink);
  background: #fff;
}

.question-paper p {
  color: #2f2f32;
  font-size: 17px;
  line-height: 1.76;
}

.question-paper p.question-stem {
  margin: 0;
  color: #2f2f32;
  font-size: 20px;
  line-height: 1.76;
}

.choices {
  display: grid;
  gap: 8px;
  margin: 16px 0 0;
  padding-left: 24px;
  color: #2f2f32;
  font-size: 16px;
  line-height: 1.56;
}

.choices li {
  padding-left: 4px;
}

.question-choices {
  padding-left: 0;
  list-style: none;
}

.question-choices li {
  display: grid;
  grid-template-columns: 24px minmax(0, 1fr);
  gap: 10px;
  padding: 10px 12px;
  border: 1px solid rgba(0, 0, 0, 0.08);
  border-radius: 12px;
  background: #fff;
}

.question-choices strong {
  display: grid;
  place-items: center;
  width: 24px;
  height: 24px;
  color: #fff;
  font-size: 12px;
  border-radius: 50%;
  background: #1d1d1f;
}

.question-choices span {
  min-width: 0;
}

.material-block {
  margin: 0 0 18px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: #f8f8fa;
}

.material-block > strong {
  display: block;
  color: #424245;
  font-size: 15px;
  color: #424245;
  font-weight: 720;
}

.material-text {
  margin-top: 12px;
}

.material-text p {
  margin: 0;
  color: #424245;
  font-size: 15px;
  line-height: 1.74;
  text-align: justify;
  text-indent: 2em;
}

.material-text p + p {
  margin-top: 8px;
}

.question-images {
  display: grid;
  gap: 12px;
  margin: 16px 0 0;
}

.question-image {
  min-width: 0;
  margin: 0;
  overflow-x: auto;
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: #fff;
}

.question-image img {
  display: block;
  width: max-content;
  max-width: 100%;
  height: auto;
  margin: 0 auto;
  border-radius: 10px;
}

.material-images .question-image img {
  max-height: 72vh;
}

.stem-images .question-image,
.option-images .question-image {
  background: #fbfbfd;
}

.question-image figcaption {
  margin-top: 8px;
  color: var(--muted);
  font-size: 13px;
  text-align: center;
}

.subquestion-title {
  margin: 0 0 12px;
  color: #1d1d1f;
  font-size: 15px;
  font-weight: 760;
  line-height: 1.4;
}

.question-group-case {
  background: #fff;
}

.question-group-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 18px clamp(22px, 3vw, 34px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.08);
  background: #fbfbfd;
}

.question-group-header strong {
  color: #1d1d1f;
  font-size: 18px;
  font-weight: 760;
}

.question-group-header span {
  flex: 0 0 auto;
  color: var(--muted);
  font-size: 14px;
  font-weight: 650;
}

.question-group-material {
  padding: clamp(22px, 3vw, 34px) clamp(22px, 3vw, 38px) 6px;
  background: #fff;
}

.question-group-material .material-block {
  margin-bottom: 0;
}

.group-question-stack {
  display: grid;
  gap: 0;
}

.group-question {
  display: grid;
  grid-template-columns: 1fr;
  border-top: 1px solid rgba(0, 0, 0, 0.08);
}

.group-question .question-paper,
.group-question .analysis-panel {
  padding: clamp(22px, 3vw, 34px) clamp(22px, 3vw, 38px);
}

.analysis-panel-empty {
  color: var(--muted);
}

.data-table-wrap {
  overflow-x: auto;
  margin: 16px 0 2px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: #fff;
}

.data-table {
  width: 100%;
  min-width: 430px;
  border-collapse: collapse;
  font-size: 15px;
}

.data-table th,
.data-table td {
  padding: 13px 15px;
  text-align: left;
  border-bottom: 1px solid rgba(0, 0, 0, 0.08);
}

.data-table tbody tr:last-child th,
.data-table tbody tr:last-child td {
  border-bottom: 0;
}

.data-table thead th {
  color: #1d1d1f;
  background: #f5f5f7;
}

.analysis-panel {
  display: flex;
  flex-direction: column;
  border-top: 1px solid rgba(0, 0, 0, 0.08);
  background:
    linear-gradient(180deg, rgba(251, 251, 253, 0.98), rgba(245, 245, 247, 0.98)),
    #f5f5f7;
}

.answer-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  color: #55555a;
  font-weight: 600;
}

.answer-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 34px;
  padding: 0 13px;
  color: #fff;
  font-size: 14px;
  font-weight: 760;
  border-radius: 999px;
  background: var(--blue);
}

.analysis-steps {
  display: grid;
  gap: 13px;
  margin: 24px 0 0;
  padding-left: 22px;
  color: #343437;
  line-height: 1.72;
}

.analysis-steps strong {
  color: #000;
  font-weight: 760;
}

.analysis-html {
  display: grid;
  gap: 10px;
  margin-top: 22px;
  color: #343437;
  font-size: 16px;
  line-height: 1.72;
}

.analysis-html p,
.analysis-html li {
  color: #343437;
  line-height: 1.72;
}

.analysis-html p {
  margin: 0;
}

.analysis-html strong {
  color: #000;
  font-weight: 760;
}

.analysis-html ul,
.analysis-html ol {
  display: grid;
  gap: 8px;
  margin: 0;
  padding-left: 20px;
}

.analysis-html table {
  display: block;
  max-width: 100%;
  overflow-x: auto;
  border-collapse: collapse;
  font-size: 14px;
}

.analysis-html th,
.analysis-html td {
  padding: 8px 10px;
  border: 1px solid rgba(0, 0, 0, 0.1);
}

.analysis-html hr,
.analysis-html h1,
.analysis-html h2,
.analysis-html h3 {
  display: none;
}

.mistake-note {
  display: grid;
  gap: 8px;
  margin: 20px 0 0;
  padding: 16px 18px;
  color: #5e3b00;
  line-height: 1.66;
  border: 1px solid rgba(166, 109, 0, 0.16);
  border-radius: 18px;
  background: #fff6df;
}

.mistake-note strong {
  color: #8a5a00;
  font-size: 14px;
  font-weight: 760;
}

.mistake-note span {
  line-height: 1.66;
}

.mistake-profile {
  display: grid;
  gap: 12px;
  margin-top: 22px;
  padding: 18px;
  color: #2f2f32;
  border: 1px solid rgba(0, 0, 0, 0.08);
  border-radius: 20px;
  background: rgba(255, 255, 255, 0.78);
  box-shadow: 0 14px 34px rgba(0, 0, 0, 0.05);
}

.profile-title {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

.profile-title > strong {
  color: #1d1d1f;
  font-size: 15px;
  font-weight: 780;
}

.profile-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
}

.profile-chips span {
  display: inline-flex;
  align-items: center;
  min-height: 25px;
  padding: 0 9px;
  color: #7a4c00;
  font-size: 12px;
  font-weight: 680;
  border-radius: 999px;
  background: #fff1ca;
}

.profile-field,
.profile-list {
  display: grid;
  gap: 7px;
  padding: 13px 0 0;
  border-top: 1px solid rgba(0, 0, 0, 0.08);
}

.profile-field strong,
.profile-list strong {
  color: #1d1d1f;
  font-size: 13px;
  font-weight: 760;
}

.profile-field p {
  margin: 0;
  color: #3f3f43;
  line-height: 1.66;
}

.profile-list ul {
  display: grid;
  gap: 7px;
  margin: 0;
  padding-left: 19px;
  color: #3f3f43;
  line-height: 1.58;
}

.method-takeaway {
  display: grid;
  gap: 8px;
  margin-top: 18px;
  padding: 18px;
  color: #143f68;
  border: 1px solid rgba(0, 113, 227, 0.14);
  border-radius: 18px;
  background: #edf6ff;
}

.method-takeaway strong {
  color: #005bb5;
  font-size: 14px;
  font-weight: 760;
}

.method-takeaway span {
  line-height: 1.64;
}

.question-empty {
  display: grid;
  gap: 8px;
  min-height: 180px;
  place-items: center;
  padding: 30px;
  color: var(--muted);
  text-align: center;
  border: 1px solid var(--line);
  border-radius: 26px;
  background: #f5f5f7;
}

.question-empty strong {
  color: var(--ink);
  font-size: 22px;
}

.question-pagination {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 14px;
  padding: 8px 0 0;
}

.page-button {
  min-width: 92px;
  min-height: 40px;
  padding: 0 16px;
  color: #1d1d1f;
  font: inherit;
  font-size: 14px;
  font-weight: 680;
  cursor: pointer;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  background: #fff;
  transition:
    background 160ms ease,
    border-color 160ms ease,
    color 160ms ease;
}

.page-button:hover,
.page-button:focus-visible {
  color: #fff;
  outline: none;
  border-color: var(--blue);
  background: var(--blue);
}

.page-button:disabled {
  color: #9b9ba0;
  cursor: not-allowed;
  border-color: var(--line);
  background: #f5f5f7;
}

.page-status {
  color: var(--muted);
  font-size: 14px;
  font-weight: 650;
  white-space: nowrap;
}

.load-more {
  justify-self: center;
  min-height: 44px;
  padding: 0 20px;
  color: #fff;
  font: inherit;
  font-size: 15px;
  font-weight: 650;
  cursor: pointer;
  border: 0;
  border-radius: 999px;
  background: var(--blue);
}

.load-more:hover,
.load-more:focus-visible {
  outline: none;
  background: var(--blue-dark);
}

.template-card {
  position: relative;
  overflow: hidden;
  min-height: 366px;
  padding: 30px;
  background: #fff;
}

.template-card::before {
  position: absolute;
  inset: 0 0 auto;
  height: 4px;
  content: "";
  background: var(--accent);
}

.accent-red {
  --accent: var(--red);
}

.accent-teal {
  --accent: var(--green);
}

.accent-yellow {
  --accent: #d99b00;
}

.card-topline {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--muted);
  font-size: 14px;
  font-weight: 650;
}

.mini-icon {
  display: grid;
  place-items: center;
  width: 28px;
  height: 28px;
  color: #fff;
  border-radius: 50%;
  background: var(--accent);
}

.template-card h3 {
  margin-top: 18px;
  font-size: 28px;
  font-weight: 730;
}

.template-card dl {
  display: grid;
  gap: 16px;
  margin: 26px 0 0;
}

.template-card dl div {
  padding-top: 16px;
  border-top: 1px solid var(--line);
}

.template-card dt {
  color: var(--ink);
  font-weight: 730;
}

.template-card dd {
  margin: 6px 0 0;
  color: var(--muted);
  line-height: 1.66;
}

.method-lab {
  padding: 86px 0 92px;
  background: #f5f5f7;
}

.method-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 34px;
}

.method-heading p {
  max-width: 440px;
}

.filters {
  display: flex;
  gap: 10px;
  overflow-x: auto;
  padding: 32px 0 24px;
  overscroll-behavior-inline: contain;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}

.filters::-webkit-scrollbar {
  display: none;
}

.filter-button {
  flex: 0 0 auto;
  min-height: 38px;
  padding: 0 16px;
  color: #424245;
  font: inherit;
  font-size: 14px;
  font-weight: 560;
  white-space: nowrap;
  cursor: pointer;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.82);
  transition:
    background 160ms ease,
    color 160ms ease,
    border-color 160ms ease;
}

.filter-button.is-active,
.filter-button:hover,
.filter-button:focus-visible {
  color: #fff;
  outline: none;
  border-color: var(--blue);
  background: var(--blue);
}

.question-filters {
  gap: 12px;
  padding: 16px 0 0;
}

.question-subfilters {
  gap: 6px;
  margin-top: 10px;
  padding: 0 0 12px 8px;
}

.question-subfilters[hidden] {
  display: none;
}

.question-filters .filter-button span,
.question-subfilters .filter-button span {
  margin-left: 5px;
  opacity: 0.72;
}

.question-subfilters .subfilter-button {
  min-height: 20px;
  padding: 0 8px;
  color: #fff;
  font-size: 11px;
  font-weight: 620;
  line-height: 18px;
  border-color: #000;
  background: #000;
}

.question-subfilters .subfilter-button.is-active,
.question-subfilters .subfilter-button:hover,
.question-subfilters .subfilter-button:focus-visible {
  color: #fff;
  outline: none;
  border-color: #000;
  background: #000;
}

.method-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.method-card {
  display: flex;
  flex-direction: column;
  min-height: 382px;
  padding: 28px;
  background: #fff;
  transition:
    transform 180ms ease,
    box-shadow 180ms ease,
    opacity 180ms ease;
}

.method-card[hidden] {
  display: none;
}

.method-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 24px 58px rgba(0, 0, 0, 0.12);
}

.tag {
  align-self: flex-start;
  padding: 6px 11px;
  color: #424245;
  font-size: 12px;
  font-weight: 650;
  border-radius: 999px;
  background: #f1f1f3;
}

.tag.logic {
  background: #eaf3ff;
  color: #125a9c;
}

.tag.data {
  background: #eaf7f2;
  color: #1d6d58;
}

.tag.language {
  background: #fff0e9;
  color: #9b4d2b;
}

.tag.review {
  background: #f7efff;
  color: var(--purple);
}

.method-card h3 {
  margin-top: 18px;
  font-size: 25px;
  font-weight: 730;
  line-height: 1.16;
}

.method-card p {
  margin-top: 14px;
  color: var(--muted);
  line-height: 1.72;
}

.method-card ol {
  display: grid;
  gap: 8px;
  margin: 18px 0 0;
  padding-left: 20px;
  color: #424245;
  line-height: 1.55;
}

.avoid {
  margin-top: auto;
  padding-top: 18px;
  color: #8a4a15;
  font-size: 14px;
  font-weight: 650;
}

.review-section {
  padding: 8px 0 86px;
}

.flow {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 16px;
}

.flow article {
  min-height: 232px;
  padding: 26px;
  background: #fff;
}

.flow span {
  color: var(--blue);
  font-size: 14px;
  font-weight: 760;
}

.flow h3 {
  margin-top: 32px;
  font-size: 24px;
  font-weight: 730;
}

.flow p {
  margin-top: 14px;
  color: var(--muted);
  line-height: 1.72;
}

.behavior-section {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(360px, 1.1fr);
  gap: 18px;
  align-items: stretch;
  padding: 0 0 86px;
}

.behavior-copy {
  display: grid;
  align-content: center;
  min-height: 370px;
  padding: clamp(30px, 4vw, 48px);
  border-radius: 30px;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.92), rgba(255, 255, 255, 0.8)),
    #fff;
  box-shadow: var(--shadow);
}

.signal-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.signal-list div {
  display: grid;
  align-content: center;
  min-height: 178px;
  padding: 26px;
  background: #fff;
}

.signal-list strong {
  font-size: 24px;
  font-weight: 730;
}

.signal-list span {
  margin-top: 10px;
  color: var(--muted);
  line-height: 1.58;
}

.boundary-section {
  padding: 18px 0 96px;
}

.boundary-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
  margin-top: 28px;
}

.boundary-card {
  padding: 30px;
  background: #fff;
}

.boundary-card h3 {
  font-size: 27px;
  font-weight: 730;
}

.boundary-card ul {
  display: grid;
  gap: 12px;
  margin: 24px 0 0;
  padding-left: 20px;
  color: var(--muted);
  line-height: 1.62;
}

.boundary-card.publish {
  border-top: 4px solid var(--green);
}

.boundary-card.private {
  border-top: 4px solid var(--red);
}

.site-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 30px clamp(20px, 4vw, 54px);
  color: #6e6e73;
  border-top: 1px solid rgba(0, 0, 0, 0.08);
  background: #f5f5f7;
}

@media (max-width: 980px) {
  .site-header {
    align-items: flex-start;
    flex-direction: column;
    gap: 8px;
  }

  .nav-links {
    width: 100%;
    padding-bottom: 2px;
  }

  .hero {
    min-height: clamp(680px, 82vh, 760px);
  }

  .hero-inner {
    padding-top: 88px;
  }

  .hero-visual {
    width: min(620px, calc(100% - 48px));
    margin-top: 34px;
    margin-bottom: 48px;
  }

  .intro-grid,
  .question-heading,
  .question-library-inner,
  .method-heading,
  .behavior-section {
    grid-template-columns: 1fr;
  }

  .question-heading,
  .method-heading {
    display: grid;
  }

  .question-toolbar {
    grid-template-columns: 1fr;
  }

  .question-layout {
    grid-template-columns: 1fr;
  }

  .template-grid,
  .method-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .flow {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 640px) {
  .site-header {
    min-height: 0;
    padding: 9px 16px;
  }

  .brand-mark {
    width: 29px;
    height: 29px;
    border-radius: 8px;
  }

  .brand strong {
    font-size: 13px;
  }

  .brand small {
    font-size: 11px;
  }

  .nav-links a {
    min-height: 32px;
    padding: 0 9px;
    font-size: 12px;
  }

  .section {
    width: min(100% - 28px, 1120px);
  }

  .hero {
    min-height: 700px;
  }

  .hero-inner {
    width: min(100% - 32px, 980px);
    padding: 74px 0 0;
  }

  .hero .eyebrow {
    font-size: 15px;
  }

  .hero h1 {
    font-size: clamp(42px, 12.2vw, 56px);
  }

  .hero-copy {
    font-size: 17px;
    line-height: 1.62;
  }

  .hero-actions {
    display: grid;
    grid-template-columns: 1fr;
    gap: 10px;
  }

  .primary-action,
  .secondary-action {
    width: 100%;
  }

  .hero-visual {
    width: min(350px, calc(100% - 44px));
    margin-top: 26px;
    margin-bottom: 44px;
    padding: 8px;
    border-radius: 28px;
  }

  .hero-bg {
    border-radius: 21px;
  }

  .intro-grid {
    padding: 18px 0 52px;
  }

  .signal-panel,
  .metrics-strip a,
  .question-case,
  .template-card,
  .method-card,
  .flow article,
  .behavior-copy,
  .boundary-card,
  .signal-list div {
    border-radius: 22px;
  }

  .signal-panel,
  .question-paper,
  .analysis-panel,
  .template-card,
  .method-card,
  .flow article,
  .behavior-copy,
  .boundary-card,
  .signal-list div {
    padding: 22px;
  }

  .signal-panel h2,
  .section-heading h2,
  .question-heading h2,
  .method-heading h2,
  .behavior-copy h2,
  .boundary-section h2 {
    font-size: 34px;
  }

  .reader-path li {
    grid-template-columns: 1fr;
    gap: 7px;
    padding: 16px 0;
  }

  .section-heading {
    padding: 52px 0 24px;
  }

  .question-library-hero {
    padding: 58px 0 34px;
  }

  .question-library-inner h1 {
    font-size: clamp(40px, 11vw, 56px);
  }

  .template-grid {
    padding-bottom: 56px;
  }

  .question-studio {
    padding: 58px 0 64px;
  }

  .question-browser {
    margin-top: 26px;
  }

  .question-toolbar {
    padding: 14px;
    border-radius: 22px;
  }

  .question-search input {
    min-height: 42px;
  }

  .question-filters {
    padding: 12px 0 0;
  }

  .question-subfilters {
    margin-top: 10px;
    padding: 0 0 8px 6px;
  }

  .question-stack {
    margin-top: 16px;
  }

  .question-paper p,
  .analysis-html {
    font-size: 16px;
  }

  .question-paper p.question-stem {
    font-size: 20px;
  }

  .choices {
    gap: 7px;
    margin-top: 14px;
    font-size: 15px;
  }

  .question-choices li {
    grid-template-columns: 23px minmax(0, 1fr);
    padding: 9px 11px;
  }

  .question-choices strong {
    width: 23px;
    height: 23px;
    font-size: 12px;
  }

  .material-block {
    padding: 12px 13px;
    border-radius: 16px;
  }

  .question-group-header {
    padding: 16px 18px;
  }

  .question-group-material {
    padding: 18px 14px 4px;
  }

  .group-question .question-paper,
  .group-question .analysis-panel {
    padding: 20px 18px;
  }

  .material-images .question-image {
    padding: 6px;
    border-radius: 14px;
  }

  .material-images .question-image img {
    width: 100%;
  }

  .question-pagination {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
  }

  .page-status {
    grid-column: 1 / -1;
    grid-row: 1;
    justify-self: center;
    font-size: 13px;
  }

  .page-button,
  .load-more {
    width: 100%;
  }

  .data-table {
    min-width: 390px;
    font-size: 14px;
  }

  .template-grid,
  .method-grid,
  .flow,
  .signal-list,
  .boundary-grid {
    grid-template-columns: 1fr;
  }

  .template-card,
  .method-card {
    min-height: 0;
  }

  .method-lab {
    padding: 58px 0 64px;
  }

  .review-section {
    padding-bottom: 64px;
  }

  .flow article {
    min-height: 0;
  }

  .flow h3 {
    margin-top: 26px;
  }

  .behavior-section {
    padding-bottom: 64px;
  }

  .boundary-section {
    padding-bottom: 70px;
  }

  .site-footer {
    display: grid;
    padding: 24px 18px;
  }
}