:root{--echo-border-radius-s:1px;--echo-border-radius-full:9999px}
:root,[data-theme=light]{--echo-color-accent-primary:#000;--echo-color-accent-secondary:#000000a6;--echo-color-background-base:#fff;--echo-color-background-default:#0000000d;--echo-color-background-surface:#0000001a;--echo-color-background-raised:#00000026;--echo-color-background-elevated:#0003;--echo-color-background-highest:#00000040;--echo-color-content-primary:#000;--echo-color-content-secondary:#000c;--echo-color-content-tertiary:#0009;--echo-color-content-quaternary:#0006;--echo-color-exception-constant-light:#fff;--echo-color-exception-constant-dark:#000;--echo-color-exception-inverse-light:#000;--echo-color-exception-inverse-dark:#fff;--echo-color-exception-multilayer-light:#ffffff0d;--echo-color-exception-multilayer-dark:#0000000d;--echo-color-overlay-image:#00000026;--echo-color-overlay-modal:#00000080;--echo-color-status-success:#017b22;--echo-color-status-success-surface:#ecf6ec;--echo-color-status-warning:#c54900;--echo-color-status-warning-surface:#f9f2df;--echo-color-status-error:#b51c36;--echo-color-status-error-surface:#ffede7;--echo-color-stroke-subtle:#0000001a;--echo-color-stroke-default:#00000026;--echo-color-stroke-strong:#0000004d;--echo-color-stroke-emphasis:#0006;--echo-color-stroke-decorative:#000;--echo-color-stroke-focuse:#2298ff}[data-theme=dark]{--echo-color-accent-primary:#ffffffb3;--echo-color-accent-secondary:#000000a6;--echo-color-background-base:#000;--echo-color-background-default:#ffffff0d;--echo-color-background-surface:#ffffff1a;--echo-color-background-raised:#ffffff26;--echo-color-background-elevated:#fff3;--echo-color-background-highest:#ffffff40;--echo-color-content-primary:#fff;--echo-color-content-secondary:#fffc;--echo-color-content-tertiary:#fff9;--echo-color-content-quaternary:#fff6;--echo-color-exception-constant-light:#fff;--echo-color-exception-constant-dark:#000;--echo-color-exception-inverse-light:#fff;--echo-color-exception-inverse-dark:#000;--echo-color-exception-multilayer-light:#ffffff0d;--echo-color-exception-multilayer-dark:#0000000d;--echo-color-overlay-image:#00000026;--echo-color-overlay-modal:#00000080;--echo-color-status-success:#02a528;--echo-color-status-success-surface:#001407;--echo-color-status-warning:#d65600;--echo-color-status-warning-surface:#230400;--echo-color-status-error:#f2263b;--echo-color-status-error-surface:#1e040b;--echo-color-stroke-subtle:#ffffff1a;--echo-color-stroke-default:#ffffff26;--echo-color-stroke-strong:#ffffff4d;--echo-color-stroke-emphasis:#fff6;--echo-color-stroke-decorative:#fff;--echo-color-stroke-focuse:#35a3ff}
:root,[data-theme=light],[data-theme=dark]{--echo-color-utility-box-shadow:0 8px 36px 0 #00000026}
:root{--echo-spacing-3xs:2px;--echo-spacing-xxs:4px;--echo-spacing-xs:8px;--echo-spacing-s:12px;--echo-spacing-m:16px;--echo-spacing-l:20px;--echo-spacing-xl:24px;--echo-spacing-xxl:32px;--echo-spacing-3xl:40px;--echo-spacing-4xl:48px;--echo-spacing-5xl:56px;--echo-spacing-6xl:64px}
:root{--echo-font-family-fallback:Helvetica neue, Helvetica, sans-serif;--echo-font-family-muse-sans:"Muse Sans", var(--echo-font-family-fallback);--echo-font-family-muse-sans-mono:"Muse Sans Mono", monospace;--echo-font-family-muse-display-harmony:"Muse Display Harmony", var(--echo-font-family-fallback);--echo-font-family-muse-display-symphony:"Muse Display Symphony", var(--echo-font-family-fallback);--echo-font-family:var(--echo-font-family-muse-sans);--echo-font-weight-regular:400;--echo-font-weight-medium:500;--echo-font-weight-semibold:600;--echo-font-heading-xxl:400 88px/80px var(--echo-font-family-muse-display-harmony);--echo-font-heading-xl:400 72px/68px var(--echo-font-family-muse-display-harmony);--echo-font-heading-l:400 64px/60px var(--echo-font-family-muse-display-harmony);--echo-font-heading-m:400 56px/52px var(--echo-font-family-muse-display-harmony);--echo-font-heading-s:400 44px/40px var(--echo-font-family-muse-display-harmony);--echo-font-subtitle-l:600 32px/36px var(--echo-font-family-muse-sans);--echo-font-subtitle-m:600 24px/28px var(--echo-font-family-muse-sans);--echo-font-subtitle-s:600 20px/24px var(--echo-font-family-muse-sans);--echo-font-body-l:400 17px/24px var(--echo-font-family-muse-sans);--echo-font-body-l-medium:500 17px/24px var(--echo-font-family-muse-sans);--echo-font-body-l-semibold:600 17px/24px var(--echo-font-family-muse-sans);--echo-font-body-s:400 15px/20px var(--echo-font-family-muse-sans);--echo-font-body-s-medium:500 15px/20px var(--echo-font-family-muse-sans);--echo-font-body-s-semibold:600 15px/20px var(--echo-font-family-muse-sans);--echo-font-caption-l:400 13px/16px var(--echo-font-family-muse-sans);--echo-font-caption-l-medium:500 13px/16px var(--echo-font-family-muse-sans);--echo-font-caption-l-semibold:600 13px/16px var(--echo-font-family-muse-sans);--echo-font-caption-s:400 11px/12px var(--echo-font-family-muse-sans);--echo-font-caption-s-medium:500 11px/12px var(--echo-font-family-muse-sans);--echo-font-caption-s-semibold:600 11px/12px var(--echo-font-family-muse-sans);--echo-font-mono:400 13px/16px var(--echo-font-family-muse-sans-mono)}
:root{--echo-states-default:1;--echo-states-hovered:.8;--echo-states-pending:.7;--echo-states-pressed:.6;--echo-states-disabled:.4}
:root,[data-theme=light]{--echo-action-primary-hovered:#6b5dfecc;--echo-action-primary-pressed:#6b5dfe99}[data-theme=dark]{--echo-action-primary-hovered:#8b77ffcc;--echo-action-primary-pressed:#8b77ff99}

@font-face{font-family:Muse Sans;src:url(/fonts/MuseSansVF.woff2)format("woff2");font-weight:100 900;font-style:normal;font-display:swap}:root{--fg:#1a202e;--muted:#607087;--line:#e5e7eb;--line-strong:#d2d6dc;--accent:#2e68c0;--accent-strong:#1a4f9f;--bg:var(--echo-color-background-base,#fff);--surface:#f9fafb;--on-accent:#fff;--max:880px;--ms-brand:var(--accent);--ms-brand-strong:var(--accent-strong);--ms-wide:1280px;--footer-bg:#0c0e13;--footer-fg:#fff;--footer-muted:#a9b0bd;--radius:8px;--radius-pill:9999px;--font-title-l:600 36px/1.2 var(--echo-font-family,sans-serif);--font-title-m:600 28px/1.3 var(--echo-font-family,sans-serif);--font-title-s:600 20px/1.3 var(--echo-font-family,sans-serif)}*{box-sizing:border-box}html{-webkit-text-size-adjust:100%}body{color:var(--fg);background:var(--bg);font:var(--echo-font-body-l,400 16px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif);font-family:var(--echo-font-family,-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif);margin:0}a{color:var(--accent);text-decoration:none}a:hover{text-decoration:underline}.container{width:100%;max-width:var(--max);padding:0 var(--echo-spacing-l,20px);margin:0 auto}main{min-height:60vh;padding:var(--echo-spacing-xl,32px) 0 var(--echo-spacing-4xl,56px)}.ms-header{z-index:50;background:var(--bg);border-bottom:1px solid var(--line);position:sticky;top:0}.ms-header-inner{width:100%;padding:0 var(--echo-spacing-xxl,32px);align-items:center;gap:var(--echo-spacing-xl,28px);height:64px;display:flex}.ms-logo{flex:none;align-items:center;display:inline-flex}.ms-logo-svg{width:auto;height:28px;display:block}.ms-nav{align-items:center;gap:var(--echo-spacing-l,22px);display:flex}.ms-nav-link{color:var(--fg);font:var(--echo-font-body-l,500 15px/1 inherit);align-items:center;gap:6px;font-weight:500;display:inline-flex;position:relative}.ms-nav-link:hover{color:var(--ms-brand);text-decoration:none}.ms-badge{text-transform:uppercase;letter-spacing:.04em;color:var(--ms-brand);background:color-mix(in srgb, var(--ms-brand) 14%, transparent);border-radius:var(--radius-pill);padding:3px 6px;font-size:10px;font-weight:700;line-height:1}.ms-actions{align-items:center;gap:var(--echo-spacing-m,14px);margin-left:auto;display:flex}.ms-trial,.ms-upload{color:var(--fg);white-space:nowrap;align-items:center;gap:7px;font-size:15px;font-weight:600;display:inline-flex}.ms-trial:hover,.ms-upload:hover{color:var(--ms-brand);text-decoration:none}.ms-burger{border:1px solid var(--line-strong);border-radius:var(--radius);cursor:pointer;background:0 0;flex-direction:column;justify-content:center;gap:4px;width:40px;height:40px;padding:0 9px;display:none}.ms-burger span{background:var(--fg);border-radius:2px;height:2px;display:block}.ms-nav-mobile{gap:var(--echo-spacing-m,14px);padding:var(--echo-spacing-l,18px) var(--echo-spacing-l,20px);border-top:1px solid var(--line);flex-direction:column;display:none}@media (max-width:860px){.ms-nav,.ms-trial,.ms-upload{display:none}.ms-burger,.ms-nav-mobile{display:flex}}.ms-footer{background:var(--footer-bg);color:var(--footer-muted);font:var(--echo-font-body-s,400 14px/1.5 inherit)}.ms-footer-inner{width:100%;max-width:var(--ms-wide);padding:var(--echo-spacing-4xl,48px) var(--echo-spacing-xxl,32px) var(--echo-spacing-xl,32px);margin:0 auto}.ms-footer-cols{gap:var(--echo-spacing-xxl,32px) var(--echo-spacing-l,24px);grid-template-columns:repeat(auto-fit,minmax(150px,1fr));display:grid}.ms-footer-title{font:var(--echo-font-body-l,600 16px/1.3 inherit);color:var(--footer-fg);margin:0 0 var(--echo-spacing-m,14px);font-weight:600}.ms-footer-col ul{gap:var(--echo-spacing-s,10px);flex-direction:column;margin:0;padding:0;list-style:none;display:flex}.ms-footer-col a{color:var(--footer-muted)}.ms-footer-col a:hover{color:var(--footer-fg);text-decoration:none}.ms-app-tagline{margin:0 0 var(--echo-spacing-m,14px);color:var(--footer-muted)}.ms-badges{gap:var(--echo-spacing-s,10px);flex-direction:column;display:flex}.ms-badge-link{border-radius:var(--radius);color:var(--footer-fg);border:1px solid #ffffff40;align-items:center;gap:8px;width:fit-content;padding:8px 14px;font-weight:600;display:inline-flex}.ms-badge-link:hover{border-color:var(--footer-fg);text-decoration:none}.ms-footer-bottom{align-items:center;gap:var(--echo-spacing-s,8px);margin-top:var(--echo-spacing-3xl,40px);padding-top:var(--echo-spacing-l,20px);border-top:1px solid #ffffff1f;flex-wrap:wrap;display:flex}.ms-footer-bottom a{color:var(--footer-muted)}.ms-footer-bottom a:hover{color:var(--footer-fg);text-decoration:none}h1{font:var(--font-title-l);margin:0 0 .4em}h2{font:var(--font-title-m);margin:1.6em 0 .5em}h3{font:var(--font-title-s)}.lead{font:var(--echo-font-body-l,400 18px/1.5 inherit);color:var(--muted);margin-top:0}.muted{color:var(--muted)}.page-header{margin-bottom:var(--echo-spacing-l,24px)}.card-grid{gap:var(--echo-spacing-l,24px);grid-template-columns:repeat(auto-fill,minmax(220px,1fr));margin:0;padding:0;list-style:none;display:grid}.card{border:1px solid var(--line);border-radius:var(--radius);background:var(--surface);overflow:hidden}.card-link{color:inherit;padding:0 0 var(--echo-spacing-m,16px);display:block}.card-link:hover{text-decoration:none}.card-cover{background:var(--echo-color-background-elevated,#f3f4f6);width:100%;height:auto;display:block}.card-title{font:var(--font-title-s);margin:var(--echo-spacing-s,14px) var(--echo-spacing-m,16px) var(--echo-spacing-3xs,4px)}.card-meta,.card-sub{margin:0 var(--echo-spacing-m,16px);color:var(--muted);font:var(--echo-font-body-s,400 14px/1.4 inherit)}.breadcrumbs{font:var(--echo-font-body-s,400 14px/1.4 inherit);color:var(--muted);margin-bottom:var(--echo-spacing-l,20px)}.breadcrumbs span[aria-hidden]{margin:0 4px}.pager{justify-content:space-between;gap:var(--echo-spacing-m,16px);border-top:1px solid var(--line);margin-top:var(--echo-spacing-2xl,40px);padding-top:var(--echo-spacing-l,20px);font:var(--echo-font-body-s,400 15px/1.4 inherit);display:flex}.pager-next{text-align:right}.book-header{gap:var(--echo-spacing-xl,28px);flex-wrap:wrap;align-items:flex-start;display:flex}.book-cover{border-radius:var(--radius);border:1px solid var(--line);width:220px;height:auto}.book-intro{flex:320px}.byline,.edition{color:var(--muted);margin:4px 0}.cta{margin-top:var(--echo-spacing-s,10px);padding:var(--echo-spacing-s,10px) var(--echo-spacing-l,18px);background:var(--accent);color:var(--on-accent);border-radius:var(--radius);font:var(--echo-font-body-l-semibold,600 16px/1 inherit);display:inline-block}.cta:hover{opacity:.92;text-decoration:none}.toc-sections{gap:var(--echo-spacing-2xl,36px);margin-top:var(--echo-spacing-l,20px);flex-direction:column;display:flex}.toc-section{gap:var(--echo-spacing-l,20px);flex-direction:column;display:flex}.toc-section-title{font:var(--echo-font-body-s,600 13px/1.2 inherit);text-transform:uppercase;letter-spacing:.09em;color:var(--accent);padding-bottom:var(--echo-spacing-2xs,8px);border-bottom:1px solid var(--line);margin:0;font-weight:600}.toc-chapter{border-left:3px solid var(--line-strong);padding-left:var(--echo-spacing-l,20px)}.toc-chapter-title{font:var(--font-title-s);margin:0 0 var(--echo-spacing-s,12px)}.toc-articles{gap:var(--echo-spacing-s,12px);flex-direction:column;margin:0;padding-left:1.4em;display:flex}.toc-articles li{margin:0}.toc-articles a{font:var(--echo-font-body-l-semibold,600 16px/1.4 inherit);font-weight:600}.toc-article-excerpt{color:var(--muted);font:var(--echo-font-body-s,400 14px/1.5 inherit);margin-top:2px;display:block}.teaser{border:1px solid var(--line);border-radius:var(--radius);padding:var(--echo-spacing-l,20px) var(--echo-spacing-xl,24px);margin-top:var(--echo-spacing-xl,28px);background:var(--surface)}.commerce{gap:var(--echo-spacing-5xl,48px);border-top:1px solid var(--line);margin-top:var(--echo-spacing-2xl,36px);padding-top:var(--echo-spacing-l,20px);flex-wrap:wrap;display:flex}.commerce ul{padding-left:1.1em}.prose{font:var(--echo-font-body-l,400 17px/1.7 inherit)}.prose img{max-width:100%;height:auto}.card-link--text{padding-top:var(--echo-spacing-2xs,6px)}.tag-chips{margin:var(--echo-spacing-s,12px) 0 0;gap:var(--echo-spacing-2xs,8px);flex-wrap:wrap;padding:0;list-style:none;display:flex}.tag-chip{padding:var(--echo-spacing-3xs,4px) var(--echo-spacing-s,12px);border:1px solid var(--line-strong);border-radius:var(--radius-pill);color:var(--fg);background:var(--surface);font:var(--echo-font-body-s,400 14px/1.4 inherit);display:inline-block}.tag-chip:hover{border-color:var(--accent);color:var(--accent);text-decoration:none}.chapter-header{margin-bottom:var(--echo-spacing-l,24px)}.chapter-header .byline{margin:0}.chapter-eyebrow{font:var(--echo-font-body-s,600 14px/1.4 inherit);letter-spacing:.02em;text-transform:uppercase;color:var(--muted);margin:0 0 var(--echo-spacing-s,8px);font-weight:600}.page-images{gap:var(--echo-spacing-m,16px);margin-top:var(--echo-spacing-xl,28px);flex-direction:column;display:flex}.page-images img{border:1px solid var(--line);border-radius:var(--radius);background:var(--echo-color-background-elevated,#f3f4f6);width:100%;height:auto}.paywall-slot{border:1px dashed var(--line-strong);border-radius:var(--radius);padding:var(--echo-spacing-l,20px) var(--echo-spacing-xl,24px);margin-top:var(--echo-spacing-xl,28px);background:var(--surface);text-align:center}.paywall-slot p{margin:0}.related{border-top:1px solid var(--line);margin-top:var(--echo-spacing-2xl,40px);padding-top:var(--echo-spacing-s,12px)}.book-topics{margin-top:var(--echo-spacing-xl,28px)}.author-header{gap:var(--echo-spacing-xl,28px);flex-wrap:wrap;align-items:flex-start;display:flex}.author-photo{border-radius:var(--radius);border:1px solid var(--line);width:160px;height:auto}.author-intro{flex:320px}.credentials{margin:var(--echo-spacing-s,12px) 0 0;color:var(--muted);font:var(--echo-font-body-s,400 15px/1.5 inherit);padding-left:1.1em}.author-links ul{padding-left:1.1em}