:root{--paper:#f4f5ef;--ink:#15201d;--muted:#66706b;--line:#d8ddd5;--card:#fff;--teal:#087f78;--teal-dark:#075d59;--teal-soft:#dcefeb;--lime:#d9ef72;--orange:#ef8f4e;--red:#d86055;--sidebar:#122b28;--shadow:0 18px 45px rgba(19,36,31,.09)}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--paper);color:var(--ink);font:16px/1.65 Inter,ui-sans-serif,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}a{color:inherit}button{font:inherit}.skip-link{position:fixed;left:1rem;top:-4rem;background:#fff;color:#111;padding:.7rem 1rem;z-index:100;border-radius:.5rem}.skip-link:focus{top:1rem}.reading-progress{position:fixed;z-index:80;left:278px;right:0;top:0;height:4px;background:transparent}.reading-progress span{display:block;height:100%;width:0;background:var(--lime)}
.sidebar{position:fixed;inset:0 auto 0 0;width:278px;background:var(--sidebar);color:#eef5f2;padding:34px 24px 24px;display:flex;flex-direction:column;z-index:70}.brand{display:flex;align-items:center;gap:12px;margin-bottom:36px}.brand-mark{width:42px;height:42px;display:grid;place-items:center;background:var(--lime);color:#17302b;font:800 1.25rem Georgia;border-radius:12px;transform:rotate(-4deg)}.brand strong,.brand span{display:block}.brand strong{font-size:1.02rem}.brand span{font-size:.8rem;color:#9fb4af}.course-label,.mini-label,.eyebrow{font-weight:800;text-transform:uppercase;letter-spacing:.15em;font-size:.72rem}.course-label{color:#78908a;border-bottom:1px solid #28433f;padding-bottom:13px;margin-bottom:12px}.sidebar nav{display:grid;gap:4px}.sidebar nav a{display:flex;align-items:center;gap:12px;padding:10px 12px;text-decoration:none;color:#afc2bd;border-radius:10px;font-size:.9rem;transition:.2s}.sidebar nav a span{color:#69847e;font-size:.72rem;font-weight:800}.sidebar nav a:hover,.sidebar nav a.active{color:white;background:#21423d}.sidebar nav a.active span{color:var(--lime)}.sidebar-bottom{margin-top:auto}.score-chip{display:flex;gap:11px;align-items:center;padding:13px;background:#193733;border:1px solid #294a45;border-radius:13px;margin-bottom:10px}.score-chip>span{width:30px;height:30px;display:grid;place-items:center;border-radius:50%;background:var(--lime);color:#18332d;font-weight:900}.score-chip strong,.score-chip small{display:block}.score-chip small{color:#9db1ac;font-size:.72rem}.theme-wide{width:100%;display:flex;justify-content:space-between;background:transparent;color:#9fb4af;border:0;padding:9px 5px;cursor:pointer}.theme-wide strong{color:white}.mobile-header{display:none}
main{margin-left:278px}.section{position:relative;max-width:1050px;margin:0 auto;padding:100px 72px;border-bottom:1px solid var(--line);scroll-margin-top:20px}.intro{min-height:760px;display:flex;flex-direction:column;justify-content:center}.eyebrow{color:var(--teal);margin:0 0 10px}.intro h1{font:800 clamp(3.4rem,7vw,6.5rem)/.92 Georgia,"Times New Roman",serif;letter-spacing:-.045em;margin:0 0 26px}.intro h1 em{color:var(--teal);font-weight:500}.lede{font-size:1.18rem;line-height:1.7;max-width:750px;color:#46534e;margin:0 0 38px}.route{display:flex;align-items:center;gap:13px;margin:0 0 40px}.route div{display:flex;align-items:center;gap:9px}.route b{width:31px;height:31px;display:grid;place-items:center;border-radius:50%;background:var(--ink);color:white;font-size:.78rem}.route span{font-weight:750;font-size:.88rem}.route i{color:#9da7a1;font-style:normal}.plain-callout{border-left:5px solid var(--lime);padding:19px 24px;background:var(--card);box-shadow:var(--shadow);max-width:760px}.plain-callout strong{font-size:.78rem;letter-spacing:.08em;text-transform:uppercase}.plain-callout p{margin:3px 0 0;color:#48534e}
.section-number{position:absolute;right:72px;top:88px;font:700 4.5rem/1 Georgia;color:transparent;-webkit-text-stroke:1px #bcc4bd}.section-heading{max-width:720px;margin-bottom:40px}.section-heading h2{font:800 clamp(2.5rem,5vw,4.1rem)/1 Georgia;margin:0 0 18px;letter-spacing:-.035em}.section-heading>p:last-child{font-size:1.1rem;color:var(--muted);max-width:670px}.card,.lesson-card,.concept,.cheat-grid article{background:var(--card);border:1px solid var(--line);border-radius:18px;box-shadow:var(--shadow)}.compare-grid{display:grid;grid-template-columns:1.4fr .8fr;gap:18px;margin-bottom:24px}.card{padding:28px;position:relative;overflow:hidden}.card h3{font:800 1.45rem Georgia;margin:4px 0 5px}.card p{color:var(--muted);margin:0}.card ul{padding-left:20px;margin:17px 0 0}.card li{margin:.35rem 0}.card-icon{position:absolute;right:20px;top:18px;font:800 2rem Georgia;color:var(--teal-soft)}.card.no{border-color:#edc9ad;background:#fffaf7}.card.no .card-icon{color:#f4d7c2}.answer-tag,.negative-chip{display:inline-block;margin-top:20px;padding:5px 10px;border-radius:999px;background:#ffe5d3;color:#8a4428;font-size:.72rem;font-weight:800;text-transform:uppercase;letter-spacing:.05em}.answer-tag.neutral{margin:0;background:var(--teal-soft);color:var(--teal-dark)}.lesson-card{padding:32px;margin-top:22px}.lesson-card h3{font:800 1.55rem Georgia;margin:0 0 8px}.lesson-card p{color:#4d5853}.accent-card{border-top:5px solid var(--teal)}.mini-label{color:var(--teal);margin:0 0 5px}.binary-example{display:flex;align-items:stretch;gap:13px;margin:22px 0}.binary-example>div:not(.or){display:flex;align-items:center;gap:14px;background:var(--paper);padding:17px;border-radius:13px;flex:1}.binary-example span{width:40px;height:40px;display:grid;place-items:center;background:var(--sidebar);color:white;border-radius:50%;font-weight:800}.binary-example p{margin:0;color:var(--ink)}.binary-example small{color:var(--muted)}.binary-example .or{align-self:center;color:var(--muted);font-weight:700}.takeaway{margin:24px 0 0!important;padding:17px 19px;background:var(--teal-soft);color:#1d4a45!important;border-radius:12px}.lesson-top{display:flex;align-items:flex-start;justify-content:space-between;gap:18px}.sum-badge{background:var(--lime);font-weight:850;font-size:.8rem;padding:7px 11px;border-radius:999px;white-space:nowrap}.table-wrap{overflow:auto;margin:24px 0;border:1px solid var(--line);border-radius:12px}table{width:100%;border-collapse:collapse;min-width:560px;font-variant-numeric:tabular-nums}th,td{text-align:center;padding:13px 14px;border-bottom:1px solid var(--line)}thead th{background:#edf1eb;color:#52605a;font-size:.78rem;text-transform:uppercase;letter-spacing:.05em}tbody th,tbody td:first-child{text-align:left}tbody tr:last-child td,tbody tr:last-child th{border-bottom:0}.highlight-row{background:var(--teal-soft);font-weight:750}.definition{display:grid;grid-template-columns:180px 1fr;gap:8px 22px;padding:20px;border-left:3px solid var(--teal);background:#f7f9f5}.definition strong{grid-row:1/3}.definition p{margin:0}.definition code{font-weight:750;color:var(--teal-dark)}code{font-family:"SFMono-Regular",Consolas,monospace}.mini-results{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin-top:22px}.mini-results div{padding:16px;background:var(--paper);border-radius:12px}.mini-results span,.mini-results b,.mini-results small{display:block}.mini-results span{font-size:.76rem;color:var(--muted);text-transform:uppercase;font-weight:750}.mini-results b{font:800 1.8rem Georgia;color:var(--teal);margin:3px 0}.mini-results small{color:var(--muted)}.density-card{display:grid;grid-template-columns:.9fr 1.2fr;gap:30px;align-items:center}.density-visual{height:210px;display:flex;align-items:flex-end;border-bottom:2px solid var(--ink);padding:0 8px;background:linear-gradient(to top,rgba(8,127,120,.04),transparent)}.region{display:flex;flex-direction:column;align-items:center;justify-content:end;padding-bottom:16px;border-radius:70% 70% 0 0}.region b{font:800 1.3rem Georgia}.region span{font-size:.72rem;white-space:nowrap}.r1{width:25%;height:55%;background:#9fd0c7}.r2{width:45%;height:92%;background:#45a89d;color:white}.r3{width:30%;height:60%;background:#b9c2bc}.equation-strip{grid-column:1/-1;display:flex;gap:15px;justify-content:space-between;padding-top:20px;border-top:1px solid var(--line);font-family:"SFMono-Regular",Consolas,monospace;font-size:.83rem}
.concept-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:15px}.concept{padding:25px}.concept .symbol{float:right;color:var(--teal);font:800 1.7rem Georgia}.concept h3{margin:0;font-size:1.12rem}.concept p{color:var(--muted);margin:7px 0 12px}.concept code{font-size:.85rem;background:var(--teal-soft);padding:5px 8px;border-radius:6px}.concept .contrast{font-size:.86rem;border-top:1px solid var(--line);padding-top:10px}.calc-columns{display:grid;grid-template-columns:1fr 1fr;gap:15px}.calc-columns>div{padding:22px;background:var(--paper);border-radius:14px}.calc-columns h4{font:800 1.3rem Georgia;margin:0 0 8px}.calc-columns p{display:flex;justify-content:space-between;margin:5px 0}.risk-winner{outline:2px solid var(--teal);position:relative}.risk-winner>span{position:absolute;top:-12px;right:13px;background:var(--teal);color:white;padding:3px 9px;border-radius:999px;font-size:.7rem;font-weight:800}.sign-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}.sign-grid div{padding:26px;text-align:center;background:var(--card);border:1px solid var(--line);border-radius:16px}.sign-grid strong,.sign-grid span{display:block}.sign-grid span{font:800 2rem Georgia;color:var(--teal);margin:7px}.sign-grid p{margin:0;color:var(--muted);font-size:.88rem}.warning{background:#fff4e9;border:1px solid #f0d2b6;border-left:5px solid var(--orange);padding:20px 22px;margin:20px 0;border-radius:4px 14px 14px 4px}.warning p{margin:4px 0 0;color:#765442}.truth-list{list-style:none;padding:0;margin:18px 0}.truth-list li{display:flex;gap:14px;align-items:center;padding:12px;border-bottom:1px solid var(--line)}.truth-list span{background:var(--teal-soft);color:var(--teal-dark);font-size:.7rem;font-weight:850;padding:3px 7px;border-radius:5px}.truth-list li:last-child span{background:#fee0dc;color:#873a33}.correlation-scale{padding:32px 10px}.scale-bar{height:16px;background:linear-gradient(90deg,#d85b52,#e9dece 50%,#188e84);border-radius:999px;position:relative}.scale-bar span{position:absolute;top:-30px;font-weight:800;font-size:.85rem}.scale-bar span:nth-child(1){left:0}.scale-bar span:nth-child(2){left:50%}.scale-bar span:nth-child(3){right:0}.marker{position:absolute;width:4px;height:28px;top:-6px;background:var(--ink);border:3px solid white;box-sizing:content-box;border-radius:5px}.scale-labels{display:flex;justify-content:space-between;margin-top:12px;color:var(--muted);font-size:.72rem}.scale-labels span:nth-child(2){text-align:center}.scale-labels span:nth-child(3){text-align:right}.formula-hero{display:flex;align-items:center;justify-content:center;gap:18px;background:var(--sidebar);color:white;padding:30px;border-radius:18px;font:700 1.35rem Georgia}.formula-hero>span{font-size:2.1rem}.formula-hero div{text-align:center}.formula-hero hr{border:0;border-top:1px solid white;margin:4px 0}.formula-hero.compact{max-width:380px;margin:0 auto 24px}.negative-chip{margin:0;background:#fee0dc;color:#873a33}.steps{display:grid;grid-template-columns:repeat(2,1fr);gap:12px}.steps>div{display:flex;gap:13px;padding:17px;background:var(--paper);border-radius:12px}.steps span{flex:0 0 29px;width:29px;height:29px;display:grid;place-items:center;background:var(--teal);color:white;border-radius:50%;font-weight:800;font-size:.75rem}.steps p{margin:0}.phi-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:12px;margin-top:20px}.phi-grid div{background:var(--paper);padding:18px;border-radius:12px}.phi-grid span,.phi-grid b,.phi-grid small{display:block}.phi-grid b{font:800 1.7rem Georgia;color:var(--teal)}.phi-grid small{color:var(--muted)}.normal-examples{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}.normal-examples>div{padding:20px;background:var(--paper);border-radius:14px;display:flex;flex-direction:column}.normal-examples h3{font-size:1.05rem}.normal-examples p{margin:0}.normal-examples code{font-size:.76rem;color:var(--muted);margin:8px 0}.normal-examples b{font:800 1.8rem Georgia;color:var(--teal);margin-top:auto}.cheat-section{padding-bottom:120px}.cheat-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:16px}.cheat-grid article{padding:25px}.cheat-grid h3{font:800 1.3rem Georgia;margin:0 0 12px}.cheat-grid dl{margin:0}.cheat-grid dl>div{display:contents}.cheat-grid dt,.cheat-grid dd{display:inline-block;margin:0;padding:8px 0;border-bottom:1px solid var(--line)}.cheat-grid dt{width:48%;font-weight:700}.cheat-grid dd{width:52%;text-align:right;color:var(--teal-dark);font-family:"SFMono-Regular",Consolas,monospace;font-size:.82rem}.final-note{margin-top:22px;background:var(--lime);padding:32px;border-radius:18px}.final-note span{font-size:.72rem;font-weight:850;text-transform:uppercase;letter-spacing:.13em}.final-note h3{font:800 1.8rem Georgia;margin:4px 0}.final-note p{margin:0;color:#44513c}footer{max-width:1050px;margin:0 auto;padding:36px 72px;display:flex;justify-content:space-between;gap:16px;color:var(--muted);font-size:.82rem}footer span{font-weight:800;color:var(--ink)}footer p{margin:0}footer a{color:var(--teal);font-weight:750;text-decoration:none}
body.dark{--paper:#111a18;--ink:#e9f0ed;--muted:#9aaba5;--line:#31403c;--card:#1b2724;--teal:#58c0b5;--teal-dark:#86d4cb;--teal-soft:#1d3d38;--sidebar:#08110f;--shadow:0 18px 45px rgba(0,0,0,.2)}body.dark .lede{color:#b1bfba}body.dark .lesson-card p,body.dark .plain-callout p{color:#b1bfba}body.dark .card.no{background:#271e19;border-color:#563b2b}body.dark .plain-callout,body.dark .definition{background:var(--card)}body.dark thead th{background:#24322e}body.dark .warning{background:#2b2119;border-color:#65452d;color:#f1c6a7}body.dark .warning p{color:#c9a88d}body.dark .final-note{color:#16201d}body.dark .final-note p{color:#354031}body.dark .answer-tag{background:#4b2e21;color:#f1b28d}
@media(max-width:900px){.mobile-header{position:sticky;top:0;height:62px;background:var(--sidebar);color:white;display:flex;align-items:center;justify-content:space-between;padding:0 16px;z-index:60}.menu-button,.theme-button{border:0;background:transparent;color:white;cursor:pointer;width:40px;height:40px}.menu-button span{display:block;width:21px;height:2px;background:white;margin:4px auto}.theme-button{font-size:1.25rem}.mobile-title{font-weight:800;font-size:.85rem}.sidebar{transform:translateX(-102%);transition:transform .25s}.sidebar.open{transform:translateX(0)}.scrim{position:fixed;inset:0;background:rgba(0,0,0,.45);z-index:65;opacity:0;pointer-events:none;transition:.25s}.scrim.open{opacity:1;pointer-events:auto}main{margin-left:0}.reading-progress{left:0;top:62px}.section{padding:76px 30px}.section-number{right:30px;top:62px;font-size:3.3rem}.intro{min-height:calc(100vh - 62px)}footer{margin-left:0;padding:32px 30px}}
@media(max-width:640px){body{font-size:16px}.section{padding:66px 20px}.section-number{right:20px}.intro h1{font-size:3.2rem}.route{align-items:flex-start;gap:7px}.route div{flex-direction:column;gap:3px;text-align:center}.route i{padding-top:4px}.route span{font-size:.68rem}.compare-grid,.density-card,.concept-grid,.cheat-grid,.normal-examples,.steps,.calc-columns{grid-template-columns:1fr}.binary-example{flex-direction:column}.binary-example .or{text-align:center}.definition{grid-template-columns:1fr}.definition strong{grid-row:auto}.mini-results{grid-template-columns:1fr}.density-card{gap:10px}.density-visual{height:180px}.equation-strip{flex-direction:column}.sign-grid{grid-template-columns:1fr}.scale-labels{font-size:.62rem}.phi-grid{grid-template-columns:1fr}.lesson-card{padding:22px}.lesson-top{flex-direction:column}.answer-tag.neutral,.negative-chip{align-self:flex-start}.cheat-grid dt,.cheat-grid dd{width:100%;display:block;text-align:left}.cheat-grid dt{border-bottom:0;padding-bottom:0}.cheat-grid dd{padding-top:0}footer{padding:28px 20px;flex-direction:column}.section-heading h2{font-size:2.5rem}}