:root{--bg:#08121a;--bg2:#0d1a23;--panel:#13232d;--panel2:#182b35;--border:#29414a;--ink:#f0f4ee;--muted:#a1b3b6;--teal:#b9e4cb;--aqua:#9fd5ca;--gold:#e5c78c;--black:#08121a;--max:1160px}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.7 system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;-webkit-font-smoothing:antialiased}body::selection{background:#b9e4cb;color:#101c24}a{color:inherit}a:focus-visible,button:focus-visible,input:focus-visible,select:focus-visible{outline:3px solid var(--gold);outline-offset:3px}img,svg{max-width:100%}h1,h2,h3,h4{letter-spacing:-.035em;line-height:1.13;margin-top:0}h1{font-size:clamp(2.8rem,5.3vw,5.2rem)}h2{font-size:clamp(2rem,3vw,3.1rem)}h3{font-size:1.2rem}p{margin:0 0 1.1em}button,input,select{font:inherit}button{cursor:pointer}a{text-decoration:none}em{font-family:Georgia,serif;font-weight:400}a:hover{color:var(--teal)}.container{max-width:var(--max);margin:0 auto;padding:0 28px}.narrow{max-width:1050px}.skip-link{position:absolute;left:12px;top:-60px;z-index:100;background:var(--teal);color:var(--black);padding:10px}.skip-link:focus{top:12px}.site-header{height:88px;position:relative;z-index:20;background:#09131bdc;border-bottom:1px solid #20323a;backdrop-filter:blur(14px)}.header-in{height:100%;display:flex;align-items:center;justify-content:space-between;gap:28px}.brand{display:flex;align-items:center;gap:11px;white-space:nowrap}.brand-mark{font-family:Georgia,serif;font-size:39px;letter-spacing:-4px;line-height:1;color:#f7f3e7}.brand-mark span,.footer-brand span{color:var(--teal)}.brand-copy{border-left:1px solid #50616a;padding-left:12px;font-size:10px;font-weight:700;letter-spacing:.24em;line-height:1.4;color:#a1b1b7}.brand-copy b{color:#f0f4ee}.desktop-nav{display:flex;align-items:center;gap:34px}.desktop-nav a{font-size:13px;font-weight:650;color:#c9d4d3}.desktop-nav a[aria-current],.desktop-nav a:hover{color:var(--teal)}.header-right{display:flex;align-items:center;gap:20px}.age-label{border:1px solid #3b5256;color:#bac7be;border-radius:30px;padding:7px 13px;font-size:9px;letter-spacing:.16em;white-space:nowrap;font-weight:800}.menu-toggle{display:none;background:transparent;border:0;padding:10px}.menu-toggle span{display:block;width:24px;height:2px;background:var(--ink);margin:5px 0}.mobile-menu{position:absolute;left:0;right:0;top:88px;background:#101f29;border-bottom:1px solid var(--border);padding:14px 28px 25px}.mobile-menu a{display:block;padding:10px 0;border-bottom:1px solid #334650}.eyebrow{display:flex;align-items:center;gap:13px;color:var(--teal);font-size:11px;font-weight:850;letter-spacing:.22em;text-transform:uppercase}.eyebrow>span:first-child{display:inline-block;width:27px;height:1px;background:var(--teal)}.hero{position:relative;overflow:hidden;isolation:isolate;background:radial-gradient(circle at 85% 48%,#1a3d42 0,transparent 47%),linear-gradient(155deg,#0c1e28,#09141d 62%)}.hero-glow{position:absolute;right:-260px;top:-220px;width:800px;height:800px;border:1px solid #ffffff09;border-radius:50%;box-shadow:0 0 0 110px #ffffff03,0 0 0 220px #ffffff02}.hero-layout{min-height:660px;display:grid;grid-template-columns:1.05fr .95fr;align-items:center;gap:40px;padding-top:80px;padding-bottom:90px}.hero-copy{position:relative;z-index:2}.hero h1{font-size:clamp(3.3rem,5.9vw,6rem);line-height:1.03;margin:28px 0;color:#fff9ec}.hero h1 em{color:var(--teal);font-style:italic}.hero-intro{font-size:17px;color:#b7c7ca;max-width:560px;line-height:1.75}.hero-actions{display:flex;gap:12px;flex-wrap:wrap;margin:36px 0 30px}.btn{display:inline-flex;align-items:center;justify-content:center;gap:20px;padding:14px 21px;font-weight:750;font-size:13px;border-radius:5px;transition:transform .2s,background .2s;line-height:1.4}.btn:hover{transform:translateY(-2px)}.btn-primary{color:#10272a;background:var(--teal)}.btn-primary:hover{background:#e1f3df;color:#10272a}.btn-secondary{border:1px solid #607579;color:#d6e4e2}.btn-secondary:hover{background:#ffffff0d}.btn-outlined{border:1px solid #47756a;color:var(--teal)}.hero-meta{display:flex;gap:28px;font-size:11px;letter-spacing:.025em;color:#a1b4b5}.hero-meta span:before{content:'✦';color:var(--gold);margin-right:8px}.hero-art{height:490px;position:relative;display:flex;align-items:center;justify-content:center}.orbit{position:absolute;border:1px solid #aec7bd1c;border-radius:50%;width:460px;height:460px;transform:rotate(-21deg)}.orbit-2{width:345px;height:345px}.card-stack{position:relative;width:300px;height:350px;transform:translateX(4px)}.playing-card{position:absolute;width:225px;height:320px;border-radius:17px;box-shadow:0 25px 90px #0008}.card-back{left:38px;top:22px;background:repeating-linear-gradient(45deg,#243d42,#243d42 13px,#2a4b51 13px,#2a4b51 14px);border:9px solid #d2dfd4;transform:rotate(20deg)}.card-shape{font-size:150px;color:#f2e4c921;text-align:center;margin-top:65px}.card-front{left:30px;top:6px;background:linear-gradient(140deg,#fff9ea,#dde9dc);transform:rotate(-13deg);border:7px solid #e6eee4;color:#234c46;padding:17px}.card-corner{font-family:Georgia;font-size:31px;font-weight:700;line-height:1;display:flex;flex-direction:column}.card-corner span{font-size:20px;color:#8c604b}.diamond-shape{color:#b7c8ac;font-size:115px;text-align:center;margin-top:-10px}.card-bottom{display:block;font-size:11px;letter-spacing:.2em;line-height:1.2;text-align:right;margin-top:-10px}.card-bottom b{font-size:20px;letter-spacing:.06em}.hero-badge{position:absolute;top:20px;left:0;color:#c0d8cd;font-size:9px;line-height:1.5;letter-spacing:.2em;transform:rotate(-90deg);transform-origin:left top}.hero-badge b{color:#fff}.floating-chip{position:absolute;border-radius:28px;background:#102832;border:1px solid #5f9d8f;color:#d4f0db;box-shadow:0 15px 45px #07141e;letter-spacing:.15em;font-size:10px;padding:14px 22px;font-weight:850}.chip-one{right:10px;top:115px;transform:rotate(9deg)}.chip-two{left:10px;bottom:100px;transform:rotate(-9deg)}.alert-strip{background:#cbe7d9;color:#203d3b}.alert-strip .container{min-height:84px;display:flex;align-items:center;gap:17px}.alert-strip div div{flex:1;font-size:13px}.alert-strip a{font-size:12px;font-weight:800;text-decoration:underline;white-space:nowrap}.alert-dot{width:11px;height:11px;flex:0 0 11px;border-radius:50%;background:#2e6f5d;box-shadow:0 0 0 6px #2e6f5d24}.section{padding:110px 0}.section-heading{display:flex;justify-content:space-between;align-items:flex-end;gap:30px;margin-bottom:40px}.section-heading h2,.feature-copy h2{max-width:650px;margin:20px 0}.section-heading h2 em,.feature-copy h2 em{color:var(--teal)}.section-heading p{color:var(--muted);max-width:620px}.count-label{border-top:1px solid #79958a;padding-top:10px;color:#9ab9a9;font-size:10px;font-weight:750;letter-spacing:.16em;white-space:nowrap}.guide-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:17px}.guide-card{display:flex;flex-direction:column;min-height:290px;padding:29px;background:linear-gradient(140deg,#152730,#102129);border:1px solid #31434b;border-radius:5px;transition:transform .2s,border-color .2s,background .2s}.guide-card:hover{transform:translateY(-5px);background:#1b313a;border-color:#7fac9b;color:inherit}.guide-icon{height:44px;width:44px;background:#223d40;color:#bde6ce;display:flex;align-items:center;justify-content:center;border-radius:8px;margin-bottom:21px}.card-eyebrow{color:#95c0b1;text-transform:uppercase;font-size:10px;letter-spacing:.16em;font-weight:800}.guide-card h3{margin:10px 0 8px;font-size:22px;color:#fff7eb}.guide-card p{font-size:13px;line-height:1.7;color:var(--muted);flex:1}.card-arrow{display:flex;align-items:center;gap:10px;color:var(--teal);font-size:12px;font-weight:800;margin-top:14px}.center-action{text-align:center;margin-top:35px}.feature-section{background:#101d25;padding:100px 0}.feature-grid{display:grid;grid-template-columns:1fr 1fr;gap:95px;align-items:center}.feature-visual{min-height:500px;background:radial-gradient(circle at 70% 25%,#45685a77,transparent 38%),linear-gradient(145deg,#284c48,#122b35);border:1px solid #446d63;display:flex;flex-direction:column;justify-content:space-between;padding:28px;overflow:hidden;position:relative}.feature-visual:before{content:'';position:absolute;inset:30px;border:1px solid #7b9f8526;transform:rotate(16deg) scale(1.3)}.feature-visual-top,.feature-bottom{z-index:1;font-size:10px;font-weight:750;letter-spacing:.22em;color:#dbebdb}.feature-center{font-family:Georgia,serif;color:#f5f0de;z-index:1;font-size:clamp(38px,5vw,70px);line-height:1.1;letter-spacing:-.06em}.feature-center>span{font-style:italic;color:#b8e9c4}.feature-center .dot{color:#e0ca90}.feature-copy p{font-size:15px;line-height:1.85;color:#aec3c2}.mini-checks{list-style:none;padding:0;margin:27px 0 36px}.mini-checks li{padding:12px 0;border-bottom:1px solid #2d424c;color:#d7e1d7;font-size:14px}.mini-checks li:before{content:'✓';color:var(--teal);margin-right:15px}.text-link{font-size:14px;font-weight:800;color:var(--teal);border-bottom:1px solid var(--teal);padding-bottom:5px}.spotlight{background:linear-gradient(115deg,#0c1a23,#14252c)}.spotlight-grid{display:grid;grid-template-columns:1.1fr .9fr;gap:90px;align-items:center}.spotlight h2{margin:21px 0;font-size:clamp(2rem,4vw,3.2rem)}.spotlight p{color:var(--muted)}.spotlight .btn{margin-top:12px}.source-note{font-size:11px;margin-top:15px}.spotlight-quote{border-left:1px solid #657e6d;padding:20px 0 20px 40px}.quote-mark{font:115px Georgia,serif;color:var(--teal);line-height:.7}.spotlight-quote p{font:italic 30px/1.4 Georgia,serif;color:#eee9dc}.spotlight-quote span{font-size:10px;letter-spacing:.2em;color:#8ba9a4}.math-tiles{display:grid;grid-template-columns:1fr 1fr 1fr;gap:15px}.math-tiles>div{background:#1a3038;border:1px solid #35525a;padding:28px;min-height:195px}.math-tiles span{display:block;color:#b4d6c2;letter-spacing:.13em;font-size:10px;font-weight:800;margin-bottom:20px}.math-tiles strong{display:block;font-size:35px;letter-spacing:-.04em}.math-tiles p{font-size:12px;color:#9fb4b4;margin-top:10px}.math-tiles .math-tile-action{background:#cbe7d9;color:#153a37}.math-tile-action span{color:#285f4d}.math-tile-action p{color:#234c45;font-size:15px;margin-bottom:18px}.math-tile-action a{text-decoration:underline;font-weight:800}.closing{padding:90px 0;text-align:center;background:radial-gradient(circle at 50% 115%,#1f5447,transparent 45%),#0b1a21}.closing .eyebrow{justify-content:center}.closing h2{margin:25px 0}.closing h2 em{color:var(--teal)}.closing p{max-width:600px;margin:0 auto;color:#adc3c1}.closing-links{display:flex;justify-content:center;gap:30px;margin-top:28px;font-size:13px;font-weight:750;color:var(--teal)}.footer{background:#070e14;border-top:1px solid #27353e;padding:64px 0 30px}.foot-top{display:grid;grid-template-columns:2.2fr 1fr 1fr 1fr;gap:55px}.foot-top p{color:#91a5aa;font-size:13px;max-width:310px;margin-top:18px}.footer-brand{font:36px Georgia;color:#f8f2e1}.footer-brand small{font:700 10px system-ui;letter-spacing:.2em;color:#95acae}.foot-top h3{font-size:12px;letter-spacing:.14em;color:#dcece0;margin:0 0 20px;text-transform:uppercase}.foot-top div>a:not(.footer-brand){display:block;color:#a0b0b4;font-size:13px;margin:9px 0}.foot-top a:hover{color:var(--teal)}.foot-bottom{border-top:1px solid #24333c;display:flex;justify-content:space-between;gap:25px;padding-top:26px;margin-top:55px;color:#7e959c;font-size:11px}.article-header{padding:60px 0 70px;background:radial-gradient(circle at 90% 50%,#21433a66,transparent 42%),linear-gradient(145deg,#0b1b25,#10232a);border-bottom:1px solid #28414a}.breadcrumb{display:flex;gap:13px;color:#91acae;font-size:12px;margin:0 0 42px}.breadcrumb a{text-decoration:underline;text-decoration-color:#446068}.article-header h1{max-width:870px;font-size:clamp(2.65rem,5vw,4.65rem);margin:19px 0 18px;color:#fff9ed}.article-subtitle{font-size:19px;color:#bad1cd;max-width:780px}.byline{display:flex;align-items:center;gap:13px;margin-top:30px}.author-icon{background:#284f49;color:#d3ecd4;border:1px solid #527e6f;border-radius:50%;width:43px;height:43px;display:grid;place-items:center;font-family:Georgia;font-size:17px;font-weight:700}.byline span:nth-child(2){display:grid;line-height:1.4}.byline strong{font-size:13px}.byline small{font-size:11px;color:#93a7ac}.article-layout{padding-top:70px;padding-bottom:100px;display:grid;grid-template-columns:minmax(0,730px) minmax(200px,270px);gap:85px;align-items:start}.article-text{min-width:0;color:#c4d3d1;font-size:16px;line-height:1.86}.article-text .lead{color:#e0eae4;font-size:19px;line-height:1.75}.article-text h2{color:#f7f4e8;font-size:30px;margin:55px 0 16px;scroll-margin-top:25px}.article-text h3{color:#f7f4e8;font-size:17px}.article-text p{margin-bottom:19px}.article-text a{color:var(--teal);text-decoration:underline;text-decoration-color:#579487;text-underline-offset:4px}.article-text a:hover{color:#f2f0cc}.article-text strong{color:#f1ebda}.article-text .notice{background:#172e37;border-left:3px solid var(--teal);padding:20px 22px;margin:27px 0;border-radius:0 6px 6px 0;color:#d5e4dc;font-size:14px}.article-text .notice-warn{border-color:#e1bf7d;background:#312c27}.steps{display:grid;grid-template-columns:repeat(2,1fr);gap:13px;margin:24px 0 30px}.steps>div{border:1px solid #36505a;background:#152831;padding:23px}.steps b{font:italic 26px Georgia;color:var(--teal)}.steps h3{margin:15px 0 7px}.steps p{font-size:13px;line-height:1.7;margin:0;color:#aabfbd}.table-scroll{overflow:auto;margin:26px 0}table{width:100%;border-collapse:collapse;text-align:left;min-width:540px}th{background:#21413e;color:#edf7ea;text-transform:uppercase;letter-spacing:.06em;font-size:11px}td{font-size:13px;color:#bbcacb}th,td{padding:15px 16px;vertical-align:top;border:1px solid #385057}.check-list{padding-left:0;list-style:none;margin:20px 0}.check-list li{padding:10px 0 10px 30px;position:relative;border-bottom:1px solid #2c414c}.check-list li:before{content:'✓';position:absolute;left:0;color:var(--teal)}.math-callout{display:grid;grid-template-columns:1fr 1fr;gap:12px;padding:25px;background:#173a39;border:1px solid #477263;border-radius:5px;align-items:center;margin:28px 0}.math-callout span{font-size:13px;color:#b4d0be}.math-callout strong{text-align:right;font-size:19px;letter-spacing:-.02em}.article-aside{position:sticky;top:20px}.aside-panel{border:1px solid #314950;background:#10212a;padding:24px}.aside-eyebrow{color:var(--teal);letter-spacing:.16em;font-size:11px;font-weight:850}.aside-panel nav{display:grid;margin-top:20px}.aside-panel nav a{font-size:12px;color:#b0c0c0;padding:11px 0;line-height:1.4;border-bottom:1px solid #2e4149}.aside-panel nav a:hover{color:var(--teal)}.aside-date{display:block;color:#789a9b;font-size:11px;margin-top:24px}.aside-box{background:#24463d;margin-top:16px;padding:26px;color:#e2f4e0}.aside-box-icon{color:var(--teal);margin-bottom:18px}.aside-box strong{font-size:18px}.aside-box p{font-size:12px;margin-top:8px;color:#bfd0c7}.aside-box a{font-size:12px;font-weight:800;color:#e2ecd6;text-decoration:underline}.article-related{background:#101f28;border-top:1px solid #2f434c;padding:75px 0}.section-title{margin-bottom:25px}.section-title span{font-size:10px;letter-spacing:.2em;color:var(--teal);font-weight:800}.section-title h2{margin:10px 0;font-size:31px}.faq{margin-top:60px}.faq h2{margin-bottom:20px}.faq details{border-bottom:1px solid #3a5158;padding:14px 0}.faq summary{font-size:16px;color:#f2f0e5;font-weight:700;cursor:pointer}.faq details p{padding:12px 4px 0;font-size:14px}.calc{border:1px solid #54796e;background:#142f30;padding:26px;margin:26px 0;border-radius:8px}.calc-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:14px}.calc label{font-size:12px;font-weight:750;color:#cfdfd7}.calc input,.calc select{display:block;width:100%;background:#071e24;color:#fff;padding:12px 14px;border:1px solid #537c78;border-radius:4px;margin-top:7px;min-height:48px}.calc-output{border-top:1px solid #4b6a66;padding-top:23px;display:grid;grid-template-columns:1fr 1fr;gap:18px;margin-top:22px}.calc-output span{font-size:11px;color:#a8c6b7;display:block}.calc-output strong{font-size:25px;display:block;margin-top:5px}.calc-error{color:#ffae99}.calc .small{font-size:11px;margin:15px 0 0}.muted{color:#a8bfbe}.error-main{min-height:55vh;text-align:center;padding-top:100px;padding-bottom:100px}.error-num{font:100px Georgia;color:var(--teal)}.error-main h1{font-size:38px}.error-main p{color:var(--muted)}
@media(max-width:1050px){.desktop-nav{gap:19px}.age-label{display:none}.hero-layout{grid-template-columns:1.1fr .9fr}.hero-art{transform:scale(.83);transform-origin:center}.feature-grid{gap:40px}.spotlight-grid{gap:40px}.article-layout{gap:35px}}@media(max-width:760px){.container{padding-left:20px;padding-right:20px}.site-header{height:73px}.header-in{height:73px}.desktop-nav{display:none}.menu-toggle{display:block}.mobile-menu{top:73px}.hero-layout{grid-template-columns:1fr;padding-top:75px;padding-bottom:70px;gap:10px}.hero-art{height:300px;transform:scale(.73);margin:20px 0 0}.hero h1{font-size:clamp(3rem,9.4vw,4.4rem)}.hero-intro{font-size:15px}.hero-meta{flex-wrap:wrap;gap:10px}.hero-meta span{font-size:10px}.alert-strip .container{padding-top:22px;padding-bottom:22px;align-items:flex-start;flex-wrap:wrap}.alert-strip div div{flex:1 1 calc(100% - 40px)}.alert-strip a{margin-left:27px}.section,.feature-section{padding:65px 0}.section-heading{display:block}.section-heading h2{font-size:2.45rem}.count-label{display:inline-block;margin-top:8px}.guide-grid{grid-template-columns:1fr 1fr}.feature-grid,.spotlight-grid{grid-template-columns:1fr;gap:40px}.feature-visual{min-height:380px}.feature-center{font-size:55px}.math-tiles{grid-template-columns:1fr 1fr}.math-tile-action{grid-column:span 2}.foot-top{grid-template-columns:repeat(2,1fr);gap:35px}.foot-top>div:first-child{grid-column:span 2}.foot-bottom{display:block}.foot-bottom span{display:block;margin-bottom:9px}.article-header{padding:38px 0 47px}.article-header h1{font-size:clamp(2.45rem,8vw,3.8rem)}.article-subtitle{font-size:16px}.breadcrumb{margin-bottom:28px}.article-layout{display:block;padding-top:42px;padding-bottom:70px}.article-text{font-size:15px}.article-text .lead{font-size:17px}.article-text h2{font-size:27px;margin-top:40px}.article-aside{display:none}.article-related{padding:60px 0}}@media(max-width:500px){.guide-grid{grid-template-columns:1fr}.hero-actions{display:grid}.hero-art{margin:25px 0 0}.math-tiles{grid-template-columns:1fr}.math-tile-action{grid-column:auto}.steps{grid-template-columns:1fr}.calc-grid,.calc-output{grid-template-columns:1fr}.math-callout{grid-template-columns:1fr}.math-callout strong{text-align:left}.spotlight-quote{padding-left:25px}.foot-top{grid-template-columns:1fr}.foot-top>div:first-child{grid-column:auto}.closing-links{flex-wrap:wrap}.hero h1{font-size:3.15rem}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*::before,*::after{transition:none!important;animation:none!important}}