:root {
  --bg: #f5f2ed;
  --bg-panel: #fcfbf8;
  --bg-card: rgba(255, 255, 255, 0.94);
  --bg-dark: #17202a;
  --text: #182027;
  --text-muted: #42505d;
  --text-light: #687686;
  --border: #d8d3ca;
  --border-strong: #b9c3cf;
  --accent: #1f4a63;
  --accent-soft: #dbe9ef;
  --accent-deep: #123347;
  --accent-warm: #9c6532;
  --warning-bg: #f8efe6;
  --warning-border: #d7b28c;
  --success-bg: #eef5ef;
  --success-border: #9fbc9a;
  --shadow: 0 18px 38px rgba(24, 32, 39, 0.08);
  --shadow-soft: 0 8px 24px rgba(24, 32, 39, 0.05);
  --serif: "Libre Baskerville", "Georgia", serif;
  --sans: "Source Sans 3", "Segoe UI", system-ui, sans-serif;
  --max-width: 980px;
  --space: 1.5rem;
  --radius: 18px;
  --fixed-canvas-width: 1280px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  font-size: 18px;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--sans);
  line-height: 1.72;
  color: var(--text);
  background:
    radial-gradient(circle at top left, rgba(31, 74, 99, 0.09), transparent 28rem),
    linear-gradient(180deg, #f7f3ee 0%, #f4f0ea 100%);
  -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3,
.heading-serif {
  margin: 0;
  font-family: var(--serif);
  font-weight: 400;
  line-height: 1.2;
  color: var(--text);
}

h1 {
  font-size: 3.6rem;
  letter-spacing: -0.035em;
}

h2 {
  font-size: 1.72rem;
  margin-bottom: 1rem;
  color: var(--accent-deep);
}

h3 {
  font-size: 1.08rem;
  margin-bottom: 0.6rem;
  color: var(--accent);
}

p {
  margin: 0 0 1rem;
  color: var(--text-muted);
}

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid rgba(31, 74, 99, 0.28);
  transition: color 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
}

a:hover {
  color: var(--accent-deep);
  border-bottom-color: var(--accent-deep);
}

em {
  font-style: italic;
}

pre,
code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
}

ul,
ol {
  margin: 0 0 1.2rem;
  padding-left: 1.25rem;
  color: var(--text-muted);
}

li {
  margin-bottom: 0.45rem;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0 1.25rem;
  background: rgba(255, 255, 255, 0.76);
  border: 1px solid rgba(185, 195, 207, 0.35);
  border-radius: 16px;
  overflow: hidden;
}

th,
td {
  padding: 0.9rem 0.95rem;
  vertical-align: top;
  text-align: left;
  border-bottom: 1px solid rgba(216, 211, 202, 0.75);
}

th {
  background: rgba(31, 74, 99, 0.06);
  color: var(--accent-deep);
  font-family: var(--serif);
  font-weight: 400;
}

tbody tr:last-child td {
  border-bottom: none;
}

hr {
  margin: 1rem 0;
  border: 0;
  border-top: 1px solid rgba(216, 211, 202, 0.85);
}

.oer-wrap {
  width: var(--fixed-canvas-width);
  max-width: none;
  margin: 0 auto;
  padding: 0 var(--space) 4rem;
}

.oer-header {
  position: relative;
  margin-bottom: 2rem;
  padding: 1.1rem 0;
  background: rgba(23, 32, 42, 0.93);
  backdrop-filter: blur(10px);
  box-shadow: 0 1px 0 rgba(255, 255, 255, 0.04);
}

.oer-header .oer-wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding-bottom: 0;
}

.oer-header nav {
  flex: 1;
  min-width: 0;
}

.oer-logo {
  font-family: var(--serif);
  font-size: 1rem;
  letter-spacing: 0.02em;
  flex: 0 0 auto;
}

.oer-logo a,
.oer-footer a,
.oer-nav a,
.btn-metal,
.btn-subtle,
.btn-pill,
.oer-toc a,
.oer-inline-cite,
.persona-card,
.task-card,
.quick-card,
.next-step-card,
.guide-card,
.route-card,
.mini-link-card {
  border-bottom: none;
}

.oer-logo a {
  color: #f8f6f2;
}

.oer-logo a:hover {
  color: #ffffff;
}

.oer-nav {
  display: flex;
  flex-wrap: nowrap;
  justify-content: flex-end;
  gap: 0.65rem 0.9rem;
  list-style: none;
  margin: 0;
  padding: 0;
  white-space: nowrap;
  overflow-x: auto;
}

.oer-nav a {
  color: rgba(240, 244, 247, 0.76);
  font-size: 0.88rem;
}

.oer-nav a:hover,
.oer-nav a[aria-current="page"] {
  color: #ffffff;
}

.oer-hero,
.start-hero {
  margin: 0 0 2rem;
  border: 1px solid rgba(185, 195, 207, 0.45);
  border-radius: 30px;
  background:
    linear-gradient(135deg, rgba(255, 255, 255, 0.93), rgba(248, 244, 238, 0.98)),
    var(--bg-panel);
  box-shadow: var(--shadow);
}

.oer-hero {
  padding: 3rem;
}

.start-hero {
  padding: 3.5rem;
  position: relative;
  overflow: hidden;
}

.start-hero::after {
  content: "";
  position: absolute;
  inset: auto -6rem -7rem auto;
  width: 16rem;
  height: 16rem;
  border-radius: 999px;
  background: radial-gradient(circle, rgba(31, 74, 99, 0.18), rgba(31, 74, 99, 0));
}

.start-hero-grid {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(18rem, 0.95fr);
  gap: 1.25rem;
  align-items: start;
}

.eyebrow {
  display: inline-block;
  margin-bottom: 0.85rem;
  font-size: 0.78rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
}

.page-title {
  margin-bottom: 0.85rem;
}

.page-subtitle {
  max-width: 45rem;
  margin: 0 0 1.75rem;
  font-size: 1.02rem;
  color: var(--text-light);
}

.lead {
  max-width: 42rem;
  margin-bottom: 1.35rem;
  font-size: 1.08rem;
}

.hero-actions,
.action-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
}

.hero-panel,
.page-kicker,
.guide-strip,
.section-shell,
.quick-answer,
.next-step-panel {
  padding: 1.1rem 1.15rem;
  border: 1px solid rgba(185, 195, 207, 0.42);
  border-radius: 22px;
  background: rgba(255, 255, 255, 0.84);
  box-shadow: var(--shadow-soft);
}

.hero-panel {
  align-self: end;
}

.page-kicker p:last-child,
.hero-panel p:last-child,
.guide-strip p:last-child,
.next-step-panel p:last-child {
  margin-bottom: 0;
}

.hero-panel-title,
.panel-title {
  display: block;
  margin-bottom: 0.4rem;
  color: var(--accent-deep);
  font-weight: 700;
  letter-spacing: 0.02em;
}

.oer-section {
  margin-bottom: 2rem;
  padding: 1.45rem 1.45rem 1.6rem;
  border: 1px solid rgba(216, 211, 202, 0.82);
  border-radius: 24px;
  background: rgba(252, 251, 248, 0.84);
  box-shadow: 0 8px 24px rgba(24, 32, 39, 0.03);
}

.oer-grid,
.persona-grid,
.task-grid,
.bridge-grid,
.next-step-grid,
.quick-grid,
.route-grid,
.mini-link-grid,
.guide-grid,
.tag-grid,
.metric-grid {
  display: grid;
  gap: 1rem;
}

.oer-grid.two-up,
.persona-grid,
.task-grid,
.quick-grid,
.guide-grid,
.route-grid,
.metric-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.bridge-grid,
.next-step-grid,
.mini-link-grid,
.tag-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.oer-card,
.persona-card,
.task-card,
.quick-card,
.next-step-card,
.route-card,
.guide-card,
.bridge-card,
.mini-link-card {
  display: block;
  padding: 1.15rem 1.15rem 1.1rem;
  border: 1px solid rgba(185, 195, 207, 0.42);
  border-radius: 20px;
  background: var(--bg-card);
  box-shadow: 0 10px 24px rgba(24, 32, 39, 0.035);
}

.persona-card,
.task-card,
.quick-card,
.next-step-card,
.route-card,
.guide-card,
.mini-link-card {
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}

.persona-card:hover,
.task-card:hover,
.quick-card:hover,
.next-step-card:hover,
.route-card:hover,
.guide-card:hover,
.mini-link-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow);
  border-color: rgba(31, 74, 99, 0.32);
}

.card-kicker {
  display: inline-block;
  margin-bottom: 0.45rem;
  color: var(--accent-warm);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.card-meta,
.reading-note,
.small-note {
  font-size: 0.92rem;
  color: var(--text-light);
}

.oer-card p:last-child,
.persona-card p:last-child,
.task-card p:last-child,
.quick-card p:last-child,
.next-step-card p:last-child,
.route-card p:last-child,
.guide-card p:last-child,
.bridge-card p:last-child,
.mini-link-card p:last-child {
  margin-bottom: 0;
}

.tight-table {
  margin-bottom: 0;
}

.tight-table td,
.tight-table th {
  padding: 0.55rem 0.75rem;
}

.accent-card {
  background:
    linear-gradient(180deg, rgba(219, 233, 239, 0.58), rgba(255, 255, 255, 0.92)),
    var(--bg-card);
}

.warm-card {
  background:
    linear-gradient(180deg, rgba(248, 239, 230, 0.92), rgba(255, 255, 255, 0.94)),
    var(--bg-card);
}

.oer-note,
.info-note,
.warning-note,
.success-note {
  padding: 1rem 1.1rem;
  margin-bottom: 1rem;
  border-left: 4px solid var(--accent);
  border-radius: 14px;
  background: rgba(219, 233, 239, 0.5);
}

.oer-grid + .oer-note,
.oer-grid + .note-inline,
.oer-note + .oer-grid,
.oer-note + .oer-note {
  margin-top: 1rem;
}

.warning-note {
  border-left-color: var(--accent-warm);
  background: var(--warning-bg);
}

.success-note {
  border-left-color: #5b8761;
  background: var(--success-bg);
}

.oer-note p:last-child,
.note-inline:last-child {
  margin-bottom: 0;
}

.note-inline {
  color: var(--text-light);
}

.btn-metal,
.btn-subtle,
.btn-pill {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 2.7rem;
  padding: 0.65rem 1rem;
  border-radius: 999px;
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.btn-metal {
  border: 1px solid rgba(31, 74, 99, 0.18);
  background: linear-gradient(180deg, #ffffff 0%, #eef2f5 100%);
  color: var(--accent-deep);
  box-shadow: 0 6px 14px rgba(24, 32, 39, 0.08);
}

.btn-metal:hover {
  color: var(--accent-deep);
  background: #ffffff;
}

.btn-subtle {
  border: 1px solid rgba(31, 74, 99, 0.12);
  background: rgba(255, 255, 255, 0.75);
  color: var(--text-muted);
}

.btn-subtle:hover {
  color: var(--accent-deep);
  background: #ffffff;
}

.btn-pill {
  min-height: auto;
  padding: 0.45rem 0.82rem;
  border: 1px solid rgba(31, 74, 99, 0.14);
  background: rgba(255, 255, 255, 0.78);
  color: var(--text-muted);
  font-size: 0.75rem;
}

.oer-toc,
.pill-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  margin-bottom: 1.5rem;
}

.oer-toc a {
  display: inline-flex;
  padding: 0.42rem 0.78rem;
  border: 1px solid rgba(31, 74, 99, 0.14);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.72);
  color: var(--text-muted);
  font-size: 0.86rem;
}

.oer-toc a:hover {
  color: var(--accent-deep);
  background: #ffffff;
}

.oer-inline-cite {
  display: inline-block;
  margin-left: 0.15rem;
  color: var(--accent);
  font-size: 0.88em;
  font-weight: 600;
}

.oer-steps li {
  padding-left: 0.15rem;
}

.oer-ref-list {
  padding-left: 1.1rem;
}

.oer-ref-list li {
  margin-bottom: 0.8rem;
  font-size: 0.96rem;
}

.oer-codeblock {
  margin: 0 0 1rem;
  padding: 0.95rem 1rem;
  overflow-x: auto;
  border: 1px solid rgba(185, 195, 207, 0.42);
  border-radius: 16px;
  background: #f2f4f6;
}

.oer-codeblock pre {
  margin: 0;
  white-space: pre-wrap;
}

.oer-equation {
  display: flex;
  align-items: center;
  min-height: 4rem;
  padding: 0.9rem 1rem;
  margin: 0 0 0.9rem;
  border: 1px solid rgba(31, 74, 99, 0.12);
  border-radius: 16px;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.96), rgba(238, 242, 245, 0.9));
}

.oer-equation-main {
  width: 100%;
  color: var(--accent-deep);
  font-family: var(--serif);
  font-size: 1.1rem;
  line-height: 1.45;
  text-align: center;
}

.guide-label,
.section-label {
  display: block;
  margin-bottom: 0.45rem;
  color: var(--accent-warm);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.persona-list,
.task-list,
.tag-list,
.risk-list {
  margin-bottom: 0;
}

.persona-list li,
.task-list li,
.tag-list li,
.risk-list li {
  margin-bottom: 0.35rem;
}

.bridge-card h3,
.guide-card h3,
.next-step-card h3,
.route-card h3,
.persona-card h3,
.task-card h3,
.quick-card h3,
.mini-link-card h3 {
  margin-bottom: 0.55rem;
}

.bridge-card {
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.96), rgba(238, 242, 245, 0.9));
}

.quick-answer {
  margin-bottom: 2rem;
  background:
    linear-gradient(145deg, rgba(18, 51, 71, 0.98), rgba(29, 69, 95, 0.95));
  color: #eff5f8;
}

.quick-answer h2,
.quick-answer h3,
.quick-answer p,
.quick-answer li,
.quick-answer .panel-title,
.quick-answer .small-note {
  color: inherit;
}

.quick-answer .quick-card {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.15);
  box-shadow: none;
}

.next-step-panel {
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.95), rgba(245, 248, 250, 0.96));
}

.next-step-card {
  background: rgba(255, 255, 255, 0.98);
}

.route-card {
  min-height: 100%;
}

.route-card .card-kicker {
  color: var(--accent);
}

.repo-grid {
  align-items: stretch;
}

.repo-card {
  display: flex;
  flex-direction: column;
  min-height: 13.5rem;
}

.repo-card h3 {
  overflow-wrap: anywhere;
  word-break: break-word;
}

.repo-card a {
  margin-top: auto;
  align-self: flex-start;
}

.research-banner {
  padding: 1.3rem 1.25rem;
}

.research-banner-kicker {
  margin-bottom: 0.45rem;
  color: #9c6532;
  font-size: 0.84rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.research-banner h2 {
  margin-bottom: 0.65rem;
  color: #6f441e;
}

.compare-table td strong,
.compare-table th strong {
  color: var(--accent-deep);
}

.oer-footer {
  margin-top: 2.5rem;
  padding: 1.2rem 0 0.4rem;
  border-top: 1px solid rgba(216, 211, 202, 0.8);
  font-size: 0.92rem;
}

.text-light {
  color: var(--text-light);
}

.mb-0 {
  margin-bottom: 0;
}

.lang-switch {
  position: absolute;
  top: 1.6rem;
  right: 2rem;
  z-index: 100;
}

.btn-lang {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.2);
  padding: 4px 12px;
  border-radius: 20px;
  text-decoration: none;
  font-size: 0.8rem;
  color: #fff;
  font-weight: 600;
  transition: all 0.2s ease;
  backdrop-filter: blur(5px);
  border-bottom: none;
}

.btn-lang:hover {
  background: rgba(255, 255, 255, 0.2);
  border-color: rgba(255, 255, 255, 0.4);
  color: #fff;
}

@media (max-width: 960px) {
  /* Fixed layout mode: keep desktop proportions on all viewport sizes. */
}

@media (max-width: 760px) {
  /* Fixed layout mode: keep desktop proportions on all viewport sizes. */
}