/* =========================================================
   /game-essay/ — course write-ups in the OpenAI docs idiom:
   fixed left nav with numbered entries, breadcrumb bar,
   one reading column with an "On this page" rail, dark code.
   Shares tokens, fonts and .prose with site.css.
   ========================================================= */

.essay-app {
  --es-side: #f9f9f9;
  --es-hover: #ececec;
  --es-active: #e6e6e6;
  --es-main: #ffffff;
  --es-card: #ffffff;
  --es-ink: #0d0d0d;
  --es-ink-2: #5d5d5d;
  --es-ink-3: #8f8f8f;
  --es-line: #e8e8e8;
  --es-chip: #f2f2f2;
  --es-code: #0d0d0d;
  --es-code-ink: #e8e8e8;
  --es-col: 760px;
  background: var(--es-main);
  color: var(--es-ink);
}

:root[data-theme="dark"] .essay-app {
  --es-side: #171717;
  --es-hover: #232323;
  --es-active: #2a2a2a;
  --es-main: #212121;
  --es-card: #262626;
  --es-ink: #ececec;
  --es-ink-2: #b4b4b4;
  --es-ink-3: #8a8a8a;
  --es-line: #333333;
  --es-chip: #2f2f2f;
  --es-code: #141414;
  --es-code-ink: #e3e3e3;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .essay-app {
    --es-side: #171717;
    --es-hover: #232323;
    --es-active: #2a2a2a;
    --es-main: #212121;
    --es-card: #262626;
    --es-ink: #ececec;
    --es-ink-2: #b4b4b4;
    --es-ink-3: #8a8a8a;
    --es-line: #333333;
    --es-chip: #2f2f2f;
    --es-code: #141414;
    --es-code-ink: #e3e3e3;
  }
}

.es {
  display: flex;
  min-height: 100vh;
}

/* ---------- Sidebar ---------- */

.es-side {
  position: sticky;
  top: 0;
  flex: 0 0 272px;
  height: 100vh;
  display: flex;
  flex-direction: column;
  padding: 10px 10px 12px;
  background: var(--es-side);
  border-right: 1px solid var(--es-line);
  overflow-y: auto;
}

.es-side__top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 44px;
  padding: 0 4px 0 8px;
}

.es-brand {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  font-size: 15px;
  font-weight: 600;
  color: var(--es-ink);
}

.es-brand .brand__mark {
  height: 18px;
  width: auto;
}

.es-icon-btn {
  display: inline-grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--es-ink-2);
  cursor: pointer;
  transition: background-color 120ms ease, color 120ms ease;
}

.es-icon-btn:hover {
  background: var(--es-hover);
  color: var(--es-ink);
}

.es-close {
  display: none;
}

.es-nav {
  margin-top: 8px;
}

.es-nav__item,
.es-nav__list a {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 7px 10px;
  border-radius: 8px;
  font-size: 14px;
  line-height: 1.45;
  color: var(--es-ink-2);
  transition: background-color 120ms ease, color 120ms ease;
}

.es-nav__item {
  align-items: center;
  color: var(--es-ink);
  font-weight: 500;
}

.es-nav__item:hover,
.es-nav__list a:hover {
  background: var(--es-hover);
  color: var(--es-ink);
}

.es-nav__item.is-active,
.es-nav__list a.is-active {
  background: var(--es-active);
  color: var(--es-ink);
}

.es-nav__label {
  margin: 22px 10px 6px;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  color: var(--es-ink-3);
}

.es-nav__list {
  margin: 0;
  padding: 0;
  list-style: none;
}

.es-nav__no {
  flex: 0 0 auto;
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--es-ink-3);
}

.es-nav__list a.is-active .es-nav__no {
  color: var(--accent);
}

.es-nav__text {
  min-width: 0;
}

.es-side__foot {
  margin-top: auto;
  padding: 16px 4px 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  font-size: 13px;
}

.es-side__theme {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 10px;
  border: 1px solid var(--es-line);
  border-radius: 999px;
  background: transparent;
  color: var(--es-ink-2);
  font: inherit;
  font-family: var(--mono);
  font-size: 12px;
  cursor: pointer;
}

.es-side__theme:hover {
  color: var(--es-ink);
}

.es-side__home {
  color: var(--es-ink-3);
}

.es-side__home:hover {
  color: var(--es-ink);
}

.es-scrim {
  display: none;
}

/* ---------- Main column ---------- */

.es-main {
  flex: 1 1 auto;
  min-width: 0;
  display: flex;
  flex-direction: column;
}

.es-bar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  gap: 8px;
  height: 52px;
  padding: 0 clamp(16px, 3vw, 32px);
  background: color-mix(in srgb, var(--es-main) 88%, transparent);
  backdrop-filter: saturate(1.4) blur(10px);
  -webkit-backdrop-filter: saturate(1.4) blur(10px);
  border-bottom: 1px solid var(--es-line);
}

.es-open {
  display: none;
}

.es-crumbs {
  display: flex;
  align-items: center;
  gap: 8px;
  min-width: 0;
  font-size: 13.5px;
  color: var(--es-ink-3);
  white-space: nowrap;
  overflow: hidden;
}

.es-crumbs a {
  color: var(--es-ink-3);
}

.es-crumbs a:hover {
  color: var(--es-ink);
}

.es-crumbs [aria-current] {
  color: var(--es-ink);
  overflow: hidden;
  text-overflow: ellipsis;
}

.es-content {
  flex: 1 1 auto;
  padding: clamp(28px, 5vw, 56px) clamp(16px, 4vw, 48px) 96px;
}

.es-eyebrow {
  margin: 0 0 12px;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.02em;
  color: var(--accent);
}

/* ---------- Index ---------- */

.es-index {
  max-width: 980px;
  margin: 0 auto;
}

.es-hero__title {
  margin: 0;
  font-size: clamp(32px, 4.6vw, 44px);
  font-weight: 600;
  line-height: 1.12;
  letter-spacing: -0.02em;
}

.es-hero__lead {
  max-width: 700px;
  margin: 16px 0 0;
  font-size: 16.5px;
  line-height: 1.75;
  color: var(--es-ink-2);
}

.es-facts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  margin: 28px 0 0;
  border: 1px solid var(--es-line);
  border-radius: 12px;
  overflow: hidden;
}

.es-facts div {
  padding: 12px 16px;
  border-right: 1px solid var(--es-line);
  margin-right: -1px;
}

.es-facts dt {
  font-family: var(--mono);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--es-ink-3);
}

.es-facts dd {
  margin: 4px 0 0;
  font-size: 13.5px;
  line-height: 1.5;
}

.es-latest {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
  margin-top: 36px;
  border: 1px solid var(--es-line);
  border-radius: 16px;
  background: var(--es-card);
  overflow: hidden;
  color: var(--es-ink);
  transition: border-color 160ms ease, box-shadow 160ms ease;
}

.es-latest:hover {
  border-color: var(--es-ink-3);
  box-shadow: 0 6px 24px rgba(0, 0, 0, 0.06);
}

.es-latest__media {
  background: #000;
  aspect-ratio: 16 / 10;
}

.es-latest__media img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.es-latest__body {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 8px;
  padding: 24px 26px;
}

.es-chip {
  padding: 3px 9px;
  border-radius: 999px;
  background: var(--es-chip);
  font-family: var(--mono);
  font-size: 11px;
  color: var(--es-ink-2);
}

.es-latest__no {
  margin-top: 6px;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--es-ink-3);
}

.es-latest__title {
  font-size: 22px;
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: -0.01em;
}

.es-latest__summary {
  font-size: 14.5px;
  line-height: 1.65;
  color: var(--es-ink-2);
}

.es-latest__cta {
  margin-top: auto;
  padding-top: 10px;
  font-size: 14px;
  font-weight: 500;
}

.es-section-title {
  margin: 52px 0 8px;
  font-size: 13px;
  font-family: var(--mono);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--es-ink-3);
}

.es-list {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--es-line);
}

.es-row {
  border-bottom: 1px solid var(--es-line);
}

.es-row__link {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr) 168px;
  gap: 18px;
  align-items: start;
  padding: 20px 8px;
  border-radius: 10px;
  color: var(--es-ink);
  transition: background-color 120ms ease;
}

.es-row__link:hover {
  background: var(--es-side);
}

.es-row__no {
  padding-top: 3px;
  font-family: var(--mono);
  font-size: 13px;
  color: var(--es-ink-3);
}

.es-row__body {
  display: flex;
  flex-direction: column;
  gap: 6px;
  min-width: 0;
}

.es-row__title {
  font-size: 17px;
  font-weight: 600;
  line-height: 1.4;
}

.es-row__summary {
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  font-size: 14.5px;
  line-height: 1.6;
  color: var(--es-ink-2);
}

.es-row__meta {
  display: flex;
  gap: 14px;
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--es-ink-3);
}

.es-row__thumb {
  aspect-ratio: 16 / 10;
  border: 1px solid var(--es-line);
  border-radius: 8px;
  background: #000;
  overflow: hidden;
}

.es-row__thumb img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* ---------- Essay page ---------- */

.es-doc {
  display: grid;
  grid-template-columns: minmax(0, var(--es-col)) 220px;
  justify-content: center;
  gap: clamp(32px, 5vw, 72px);
}

.es-article {
  min-width: 0;
}

.es-head {
  padding-bottom: 28px;
  margin-bottom: 36px;
  border-bottom: 1px solid var(--es-line);
}

.es-head__title {
  margin: 0;
  font-size: clamp(28px, 4vw, 38px);
  font-weight: 600;
  line-height: 1.18;
  letter-spacing: -0.02em;
}

.es-head__lead {
  margin: 14px 0 0;
  font-size: 16.5px;
  line-height: 1.7;
  color: var(--es-ink-2);
}

.es-head__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 16px;
  margin: 18px 0 0;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--es-ink-3);
}

.es-aside__label {
  margin: 0;
  font-size: 12.5px;
  font-weight: 600;
  color: var(--es-ink);
}

.es-toc {
  top: 84px;
  max-width: none;
  max-height: calc(100vh - 110px);
}

.es-toc ol {
  border-left-color: var(--es-line);
}

.es-toc a {
  font-size: 13px;
  color: var(--es-ink-3);
}

/* Prose tuned for technical English: tighter leading, dark code panels. */

.es-prose {
  font-size: 16px;
  line-height: 1.75;
  color: var(--es-ink);
}

.es-prose h2 {
  margin-top: 2.4em;
  padding-top: 0.2em;
  font-size: 23px;
  letter-spacing: -0.01em;
  scroll-margin-top: 72px;
}

.es-prose h3 {
  font-size: 18px;
  scroll-margin-top: 72px;
}

.es-prose a {
  color: var(--es-ink);
  text-decoration: underline;
  text-decoration-color: var(--es-ink-3);
  text-underline-offset: 3px;
}

.es-prose a:hover {
  text-decoration-color: var(--es-ink);
}

.es-prose code {
  border-color: var(--es-line);
  background: var(--es-chip);
}

.es-prose pre,
.es-prose figure.highlight {
  border: 0;
  border-radius: 12px;
  background: var(--es-code);
  color: var(--es-code-ink);
  font-size: 13px;
  line-height: 1.65;
  tab-size: 4;
}

.es-prose pre code {
  color: inherit;
  background: transparent;
}

.es-prose figure.highlight .hljs-comment,
.es-prose figure.highlight .hljs-quote,
.es-prose pre .hljs-comment {
  color: #8b8b8b;
}

.es-prose figure.highlight .hljs-keyword,
.es-prose figure.highlight .hljs-selector-tag,
.es-prose figure.highlight .hljs-literal,
.es-prose figure.highlight .hljs-section,
.es-prose figure.highlight .hljs-type,
.es-prose figure.highlight .hljs-name,
.es-prose pre .hljs-keyword,
.es-prose pre .hljs-type {
  color: #ff8a65;
}

.es-prose figure.highlight .hljs-string,
.es-prose figure.highlight .hljs-attr,
.es-prose figure.highlight .hljs-symbol,
.es-prose figure.highlight .hljs-bullet,
.es-prose figure.highlight .hljs-addition,
.es-prose pre .hljs-string {
  color: #9ece6a;
}

.es-prose figure.highlight .hljs-number,
.es-prose figure.highlight .hljs-meta,
.es-prose figure.highlight .hljs-built_in,
.es-prose figure.highlight .hljs-title,
.es-prose figure.highlight .hljs-variable,
.es-prose figure.highlight .hljs-template-variable,
.es-prose pre .hljs-number,
.es-prose pre .hljs-title,
.es-prose pre .hljs-built_in {
  color: #7dcfff;
}

.es-prose blockquote {
  margin-left: 0;
  margin-right: 0;
  padding: 14px 18px;
  border: 1px solid var(--es-line);
  border-left: 3px solid var(--accent);
  border-radius: 10px;
  background: var(--es-side);
  color: var(--es-ink);
  font-style: normal;
}

.es-prose blockquote > :first-child {
  margin-top: 0;
}

.es-prose table {
  font-size: 14px;
}

.es-prose th,
.es-prose td {
  border-color: var(--es-line);
}

.es-prose img {
  border: 1px solid var(--es-line);
  border-radius: 10px;
}

.es-prose hr {
  border: 0;
  border-top: 1px solid var(--es-line);
}

.es-pager {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin-top: 56px;
}

.es-pager__link {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 16px 18px;
  border: 1px solid var(--es-line);
  border-radius: 12px;
  color: var(--es-ink);
  transition: border-color 160ms ease;
}

.es-pager__link:hover {
  border-color: var(--es-ink-3);
}

.es-pager__link--next {
  grid-column: 2;
  text-align: right;
}

.es-pager__dir {
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--es-ink-3);
}

.es-pager__title {
  font-size: 15px;
  font-weight: 500;
  line-height: 1.4;
}

/* ---------- Responsive ---------- */

@media (max-width: 1180px) {
  .es-doc {
    grid-template-columns: minmax(0, var(--es-col));
  }

  .es-aside {
    display: none;
  }
}

@media (max-width: 900px) {
  .es-side {
    position: fixed;
    inset: 0 auto 0 0;
    z-index: 60;
    width: min(300px, 86vw);
    transform: translateX(-100%);
    transition: transform 220ms var(--ease);
  }

  .es.is-open .es-side {
    transform: none;
  }

  .es.is-open .es-scrim {
    display: block;
    position: fixed;
    inset: 0;
    z-index: 50;
    background: rgba(0, 0, 0, 0.35);
  }

  .es-open,
  .es-close {
    display: inline-grid;
  }

  .es-bar {
    padding-left: 8px;
  }
}

@media (max-width: 720px) {
  .es-latest {
    grid-template-columns: 1fr;
  }

  .es-row__link {
    grid-template-columns: 32px minmax(0, 1fr);
    gap: 12px;
    padding: 18px 4px;
  }

  .es-row__thumb {
    display: none;
  }

  .es-pager {
    grid-template-columns: 1fr;
  }

  .es-pager__link--next {
    grid-column: 1;
  }
}