/* Major sections inherit the shared responsive 1500px .arena-shell.
   Keep narrower text and diagrams inside that shell, never on the outer grid. */
.arena-guide-breadcrumb { display: flex; flex-wrap: wrap; gap: 7px; align-items: center; margin-bottom: 30px; color: var(--arena-muted); font-size: 13px; }
.arena-guide-breadcrumb a { color: var(--arena-muted); }
.arena-guide-breadcrumb [aria-current="page"] { min-width: 0; max-width: min(42ch, 100%); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.arena-guide-archive-hero { padding: 56px 0 66px; border-bottom: 1px solid var(--arena-line); background: radial-gradient(circle at 91% 14%, #dff8f0 0, transparent 29%), radial-gradient(circle at 9% 95%, #e7ecff 0, transparent 34%), #fbfcff; }
.arena-guide-archive-intro { text-align: center; }
.arena-guide-archive-intro .arena-guide-breadcrumb { justify-content: center; }
.arena-guide-archive-intro .arena-eyebrow { justify-content: center; }
.arena-guide-archive-intro h1 { max-width: 870px; margin: 0 auto 20px; font-size: clamp(36px, 4.3vw, 62px); letter-spacing: -1.4px; }
.arena-guide-archive-intro > p:not(.arena-eyebrow) { max-width: 780px; margin: 0 auto; color: var(--arena-muted); font-size: 18px; }
.arena-guide-topic-links { display: flex; flex-wrap: wrap; justify-content: center; gap: 10px; margin-top: 30px; }
.arena-guide-topic-links a { display: inline-flex; min-height: 44px; align-items: center; padding: 8px 15px; border: 1px solid #cbd6fb; border-radius: 999px; color: var(--arena-blue-dark); background: #fff; font-size: 14px; font-weight: 700; text-decoration: none; }
.arena-guide-topic-links a:hover { border-color: var(--arena-blue); background: #f2f5ff; }
.arena-guide-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 23px; }
.arena-guide-card { display: flex; min-width: 0; min-height: 305px; flex-direction: column; overflow: hidden; padding: 0; border: 1px solid var(--arena-line); border-radius: 20px; background: linear-gradient(155deg, #fff 40%, #f7f9ff); box-shadow: 0 12px 34px #1725540a; }
.arena-guide-card-image { display: block; aspect-ratio: 16 / 9; overflow: hidden; background: #f3f5fc; }
.arena-guide-card-image img { display: block; width: 100%; height: 100%; object-fit: cover; }
.arena-guide-card-body { display: flex; flex: 1; flex-direction: column; min-width: 0; padding: 25px; }
.arena-guide-archive-note { max-width: 650px; margin-top: 12px; color: var(--arena-muted); font-size: 15px; }
.arena-guide-card:nth-child(3n + 2) { background: linear-gradient(155deg, #fff 40%, #f0fbf7); }
.arena-guide-card:nth-child(3n + 3) { background: linear-gradient(155deg, #fff 40%, #fff8e8); }
.arena-guide-card-meta { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 22px; color: var(--arena-muted); font-size: 12px; font-weight: 700; }
.arena-guide-card-meta span { padding: 4px 9px; border-radius: 7px; background: #eef2ff; }
.arena-guide-card-meta span + span { background: #eef8f5; }
.arena-guide-card h2, .arena-guide-card h3 { margin-bottom: 13px; font-size: 22px; }
.arena-guide-card h2 a, .arena-guide-card h3 a { color: inherit; text-decoration: none; }
.arena-guide-card h2 a:hover, .arena-guide-card h3 a:hover { color: var(--arena-blue-dark); }
.arena-guide-card p { display: -webkit-box; margin-bottom: 25px; overflow: hidden; color: var(--arena-muted); font-size: 14px; -webkit-box-orient: vertical; -webkit-line-clamp: 5; }
.arena-guide-card .arena-text-link { margin-top: auto; font-size: 14px; }
.arena-guide-principles { padding: 64px 0; color: #fff; background: var(--arena-navy); }
.arena-guide-principles > .arena-shell { display: grid; grid-template-columns: .75fr 1.25fr; align-items: start; gap: 70px; }
.arena-guide-principles .arena-eyebrow { color: #9ae9d9; }
.arena-guide-principles h2 { color: #fff; font-size: clamp(27px, 2.5vw, 39px); }
.arena-guide-principles ol { display: grid; gap: 13px; margin: 0; padding: 0; list-style: none; counter-reset: guide-step; }
.arena-guide-principles li { display: grid; grid-template-columns: 42px 145px 1fr; align-items: center; gap: 15px; padding: 17px; border: 1px solid #ffffff1e; border-radius: 14px; background: #ffffff0a; counter-increment: guide-step; }
.arena-guide-principles li::before { content: "0" counter(guide-step); color: #89a4ff; font-weight: 800; }
.arena-guide-principles li strong { color: #fff; }
.arena-guide-principles li span { color: #cdd6f4; font-size: 14px; }
.arena-guide-article-hero { padding: 36px 0 32px; border-bottom: 1px solid var(--arena-line); background: radial-gradient(circle at 100% 0, #e4f9f3, transparent 33%), var(--arena-page); }
.arena-guide-article-hero .arena-guide-breadcrumb { margin-bottom: 24px; }
.arena-guide-kicker { display: flex; flex-wrap: wrap; gap: 10px; margin-bottom: 20px; }
.arena-guide-kicker span { padding: 5px 11px; border-radius: 8px; color: #244bdb; background: #e8edff; font-size: 12px; font-weight: 750; }
.arena-guide-kicker span + span { color: #8b5711; background: #fff2d5; }
.arena-guide-article-hero h1 { max-width: 960px; margin-bottom: 18px; font-size: clamp(32px, 3.4vw, 48px); letter-spacing: -1px; }
.arena-guide-lead { max-width: 820px; margin-bottom: 20px; color: var(--arena-muted); font-size: 18px; line-height: 1.8; }
.arena-guide-byline { display: flex; flex-wrap: wrap; gap: 8px 20px; color: var(--arena-muted); font-size: 13px; }
.arena-guide-cover { margin: 24px 0 0; }
.arena-guide-cover img { display: block; width: 100%; height: auto; border: 1px solid #dfe5ef; border-radius: 18px; }
.arena-guide-cover figcaption, .arena-guide-flow figcaption { margin-top: 10px; color: var(--arena-muted); font-size: 12px; line-height: 1.7; }
.arena-guide-flow { max-width: 600px; margin: 28px auto; }
.arena-guide-flow > a { display: block; border: 1px solid var(--arena-line); border-radius: 18px; overflow: hidden; }
.arena-guide-flow img { display: block; width: 100%; height: auto; }
.arena-guide-flow figcaption a { display: inline-flex; align-items: center; min-height: 44px; font-weight: 650; }
.arena-guide-route { margin: 38px 0 44px; padding-top: 4px; }
.arena-guide-route .arena-eyebrow { margin-bottom: 10px; }
.arena-guide-route h2 { margin-top: 0; }
.arena-guide-flow-text { padding: 22px; border: 1px solid #cde8e0; border-radius: 16px; background: #f2fbf7; }
.arena-guide-flow-text summary { min-height: 36px; color: var(--arena-navy); font-weight: 750; cursor: pointer; }
.arena-guide-content .arena-guide-flow-text ol { display: grid; gap: 13px; margin: 12px 0 0; padding-left: 1.35em; }
.arena-guide-flow-text li { padding-left: 4px; margin: 0; font-size: 16px; line-height: 1.85; }
.arena-content-toc { margin-bottom: 28px; padding: 24px; border: 1px solid #d7e0f5; border-radius: 16px; background: #f5f7ff; }
.arena-content-toc h2, .arena-prose .arena-content-toc h2 { margin: 0 0 12px; padding: 0; font-size: 17px; line-height: 1.6; }
.arena-content-toc ol, .arena-guide-content .arena-content-toc ol { margin: 0; padding-left: 1.25em; }
.arena-content-toc li { margin-bottom: 2px; color: var(--arena-muted); font-size: 14px; line-height: 1.7; }
.arena-content-toc a { display: inline-flex; min-height: 44px; align-items: center; padding-block: 5px; color: var(--arena-blue-dark); text-underline-offset: 4px; }
.arena-editorial-lead { max-width: 820px; margin: 22px 0 0; color: var(--arena-muted); font-size: 19px; line-height: 1.85; }
.arena-editorial-layout { display: grid; grid-template-columns: 270px minmax(0, 1fr); align-items: start; gap: 40px; }
.arena-editorial-sidebar { position: sticky; top: 24px; min-width: 0; }
.arena-editorial-sidebar .arena-content-toc { margin-bottom: 15px; padding: 21px; }
.arena-editorial-sidebar-link { display: flex; min-height: 52px; align-items: center; justify-content: space-between; gap: 10px; padding: 12px 17px; border: 1px solid #cbe8df; border-radius: 12px; background: #f1fbf7; color: #066953; font-size: 14px; font-weight: 750; text-decoration: none; }
.arena-editorial-main { min-width: 0; }
.arena-editorial-main .arena-prose { max-width: none; line-height: 1.95; }
.arena-editorial-main .arena-prose h2 { scroll-margin-top: 25px; padding-top: 6px; }
.arena-editorial-main .arena-prose h2:not(:first-child) { margin-top: 50px; padding-top: 25px; border-top: 1px solid var(--arena-line); }
.arena-editorial-main .arena-prose h3 { line-height: 1.6; }
.arena-editorial-main .arena-prose details { margin: 16px 0; padding: 17px 20px; border: 1px solid var(--arena-line); border-radius: 13px; background: #fff; }
.arena-editorial-main .arena-prose details summary { min-height: 34px; font-weight: 750; line-height: 1.7; cursor: pointer; }
.arena-editorial-main .arena-prose details p { margin-top: 15px; margin-bottom: 0; }
.arena-editorial-next { margin-top: 48px; padding: 29px; border: 1px solid #d4def6; border-radius: 18px; background: linear-gradient(130deg, #f1f5ff, #f1fbf7); }
.arena-editorial-next .arena-eyebrow { margin: 0 0 10px; }
.arena-editorial-next h2 { margin-bottom: 20px; font-size: 25px; }
.arena-editorial-next > div { display: flex; flex-wrap: wrap; gap: 10px; }
.arena-editorial-next a { display: inline-flex; min-height: 48px; align-items: center; gap: 16px; padding: 10px 15px; border: 1px solid #d0daf3; border-radius: 10px; background: #fff; color: var(--arena-blue-dark); font-size: 14px; font-weight: 750; text-decoration: none; }
.arena-editorial-notices { margin-top: 44px; }
.arena-guide-layout { display: grid; grid-template-columns: minmax(0, 1fr) 280px; align-items: start; gap: 40px; padding-top: 32px; padding-bottom: 56px; }
.arena-guide-content { max-width: none; }
.arena-guide-content > :first-child { margin-top: 0; }
.arena-guide-content h2 { scroll-margin-top: 25px; padding-top: 5px; }
.arena-guide-content ul, .arena-guide-content ol { padding-left: 1.4em; }
.arena-guide-content a { overflow-wrap: anywhere; }
.arena-guide-review-note { margin-top: 46px; padding: 22px 25px; border-left: 4px solid var(--arena-yellow); border-radius: 4px 14px 14px 4px; background: #fff9e8; }
.arena-guide-review-note strong { color: var(--arena-navy); }
.arena-guide-review-note p { margin: 7px 0 0; color: var(--arena-muted); font-size: 14px; }
.arena-guide-cta { position: sticky; top: 24px; padding: 29px; border: 1px solid #d6dff8; border-radius: 20px; background: linear-gradient(145deg, #f3f6ff, #fff); box-shadow: 0 16px 42px #1725540c; }
.arena-guide-cta h2 { margin: 17px 0 12px; font-size: 23px; }
.arena-guide-cta p { color: var(--arena-muted); font-size: 14px; }
.arena-guide-cta .arena-button { width: 100%; margin: 7px 0 14px; padding-inline: 15px; text-align: center; }
.arena-guide-cta small { display: block; color: var(--arena-muted); font-size: 11px; line-height: 1.6; text-align: center; }
.arena-guide-related { border-top: 1px solid var(--arena-line); background: var(--arena-page); }
.arena-guide-grid-related .arena-guide-card { min-height: 280px; }
.arena-home-guides { background: linear-gradient(180deg, #f7f9ff, #fff); }
.dse-subject-guides { margin-top: 22px; padding-top: 18px; border-top: 1px solid var(--arena-line); }
.dse-subject-guides h3 { margin-bottom: 9px; font-size: 16px; }
.dse-subject-guides ul { display: block; margin: 0; padding-left: 18px; }
.dse-subject-guides li { margin: 5px 0; }
.dse-subject-guides a { font-size: 14px; font-weight: 650; }

@media (max-width: 980px) {
  .arena-guide-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .arena-guide-layout { grid-template-columns: minmax(0, 1fr); gap: 32px; }
  .arena-guide-cta { position: static; }
  .arena-guide-principles > .arena-shell { grid-template-columns: 1fr; gap: 27px; }
  .arena-editorial-layout { grid-template-columns: minmax(0, 1fr); gap: 32px; }
  .arena-editorial-sidebar { position: static; }
  .arena-editorial-sidebar .arena-content-toc ol { columns: 2; column-gap: 34px; }
  .arena-editorial-sidebar .arena-content-toc li { break-inside: avoid; }
}
@media (max-width: 720px) {
  .arena-guide-archive-hero { padding: 35px 0 40px; }
  .arena-guide-article-hero { padding: 28px 0 24px; }
  .arena-guide-archive-intro { text-align: left; }
  .arena-guide-archive-intro .arena-guide-breadcrumb, .arena-guide-archive-intro .arena-eyebrow, .arena-guide-topic-links { justify-content: flex-start; }
  .arena-guide-archive-intro h1 { margin-inline: 0; font-size: 37px; }
  .arena-guide-archive-intro > p:not(.arena-eyebrow) { margin-inline: 0; font-size: 16px; }
  .arena-guide-grid { grid-template-columns: 1fr; }
  .arena-guide-card { min-height: 0; }
  .arena-guide-card-body { padding: 23px; }
  .arena-guide-card h2, .arena-guide-card h3 { font-size: 21px; }
  .arena-guide-principles { padding: 46px 0; }
  .arena-guide-principles li { grid-template-columns: 34px 1fr; }
  .arena-guide-principles li span { grid-column: 2; }
  .arena-guide-article-hero h1 { font-size: 35px; }
  .arena-guide-lead { font-size: 17px; }
  .arena-guide-layout { padding-top: 24px; padding-bottom: 50px; }
  .arena-guide-cta { padding: 24px; }
  .arena-guide-cover img, .arena-guide-flow > a { border-radius: 12px; }
  .arena-content-toc { padding: 20px; }
  .arena-content-toc a { min-height: 44px; }
  .arena-editorial-sidebar .arena-content-toc ol { columns: 1; }
  .arena-editorial-lead { margin-top: 18px; font-size: 17px; }
  .arena-editorial-main .arena-prose { line-height: 1.9; }
  .arena-editorial-next { padding: 23px; }
  .arena-editorial-next h2 { font-size: 23px; }
  .arena-editorial-next a { width: 100%; justify-content: space-between; }
  .arena-guide-flow-text { padding: 18px; }
}
@media (max-width: 420px) {
  .arena-guide-breadcrumb { gap: 5px; margin-bottom: 23px; font-size: 12px; }
  .arena-guide-archive-intro h1, .arena-guide-article-hero h1 { font-size: 31px; letter-spacing: -.6px; overflow-wrap: anywhere; }
  .arena-guide-topic-links { gap: 8px; }
  .arena-guide-topic-links a { flex: 1 1 calc(50% - 8px); justify-content: center; padding-inline: 10px; }
  .arena-guide-kicker { gap: 7px; }
  .arena-guide-lead { line-height: 1.72; }
  .arena-guide-byline { display: grid; gap: 5px; }
  .arena-guide-layout { gap: 28px; }
  .arena-guide-content { min-width: 0; overflow-wrap: anywhere; }
  .arena-guide-content pre, .arena-guide-content table { display: block; max-width: 100%; overflow-x: auto; }
  .arena-guide-cta { padding: 21px; }
  .arena-guide-cta .arena-button, .arena-guide-card .arena-text-link { min-height: 44px; }
}