:root{--ink:#17313b;--muted:#54666c;--teal:#087e79;--blue:#386aa5;--rust:#b25a36;--gold:#9b751c;--line:#d8e1df;--wash:#f1f6f4;--paper:#fffefa;--gray:#78858c;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;color:var(--ink);background:#eef2ee;font-synthesis:none}
*{box-sizing:border-box}body{margin:0}button,input,select{font:inherit}button,summary,select{cursor:pointer}button{touch-action:manipulation}a{color:var(--teal);text-underline-offset:4px}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline:3px solid var(--gold);outline-offset:4px}button:disabled{opacity:.4;cursor:default}[hidden]{display:none!important}main{max-width:1440px;min-height:100vh;margin:auto;background:var(--paper);padding:26px 48px}h1,h2,h3,p{margin-top:0}h1,h2{font-family:Georgia,"Times New Roman",serif;font-weight:500}h1{font-size:clamp(2.8rem,5vw,4.6rem);letter-spacing:-.055em;margin:9px 0 16px;line-height:1.04}h2{font-size:clamp(1.9rem,3vw,2.6rem);letter-spacing:-.035em;margin:0 0 12px;line-height:1.15}h3{font-size:1.05rem;line-height:1.4;font-weight:700;margin-bottom:12px}p{line-height:1.65}i,.math{font-family:Georgia,serif}i{font-style:italic}.math{font-size:1.15rem;line-height:1.7}.large{font-size:1.6rem;margin:12px 0}.site-line{display:flex;align-items:center;gap:20px;font-size:.68rem;font-weight:650;letter-spacing:.1em}.site-line>a{font-size:.94rem;text-decoration:none;color:var(--ink);letter-spacing:.14em}.site-line>span:nth-child(2){color:var(--muted);flex:1}.chapter-tag{background:#f2e9cf;color:#72551c;border-radius:3px;padding:6px 10px;white-space:nowrap;font-size:.67rem;letter-spacing:.03em}.hero{display:grid;grid-template-columns:1.4fr 1fr;align-items:center;gap:55px;padding:46px 0 30px}.eyebrow{font-size:.67rem;letter-spacing:.12em;font-weight:750;color:var(--teal);margin-bottom:9px;line-height:1.6}.intro{font-size:1.07rem;color:var(--muted);max-width:660px;margin-bottom:0}.hero-equation{padding:23px 0 23px 32px;border-left:1px solid var(--line)}.hero-equation>span{font-size:.85rem;color:var(--muted)}.hero-equation p{font-family:Georgia,serif;font-size:clamp(1.5rem,2.6vw,2.3rem);white-space:nowrap;margin:9px 0 4px}.hero-equation small{font-size:.75rem;color:var(--muted)}.chapters{display:grid;grid-template-columns:repeat(5,1fr);border-top:1px solid var(--line);border-bottom:1px solid var(--line);gap:0;margin-bottom:35px}.chapters button{position:relative;text-align:left;padding:17px 10px 17px 0;margin:0 14px 0 0;border:0;border-bottom:3px solid transparent;background:transparent;color:var(--muted);font-weight:650;font-size:.86rem;line-height:1.5}.chapters button>span{display:block;font-size:.67rem;letter-spacing:.1em;font-weight:500;margin-bottom:5px}.chapters button>small{display:block;font-size:.7rem;font-weight:400;margin-top:5px}.chapters button[aria-current]{border-bottom-color:var(--teal);color:var(--ink)}.chapters button:hover{color:var(--teal)}.panel-heading{display:flex;justify-content:space-between;align-items:center;gap:30px;margin-bottom:20px}.panel-heading p:last-child{color:var(--muted);max-width:810px;margin-bottom:0}.panel-heading .quiet{white-space:nowrap;font-size:.8rem}.scenario-row{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin:20px 0 28px}.scenario-row>span{font-size:.78rem;color:var(--muted);margin-right:8px}button{border:1px solid #b9cac6;background:var(--paper);color:var(--ink);border-radius:5px;padding:10px 13px;font-size:.8rem;line-height:1.4;min-height:40px}button:hover{background:#edf4f1;border-color:var(--teal)}button.primary{background:var(--teal);color:#fff;border-color:var(--teal)}button.primary:hover{background:#086b67}button.quiet{border-color:transparent;color:var(--teal);background:transparent}.scenario-row button[aria-pressed=true]{background:var(--ink);color:#fff;border-color:var(--ink)}.wide{width:100%}.lab-layout{display:grid;grid-template-columns:245px minmax(0,1fr);gap:38px;border-top:1px solid var(--line);padding-top:25px}.controls{border-right:1px solid var(--line);padding-right:27px}.controls>h3{font-size:1rem}.control{margin:23px 0}.control label{display:flex;align-items:baseline;gap:7px;font-size:.84rem;font-weight:600;line-height:1.5}.control label>i{font-size:1rem;font-weight:400}.control output{margin-left:auto;white-space:nowrap;font-variant-numeric:tabular-nums;font-weight:750;color:var(--teal)}input[type=range]{display:block;width:100%;accent-color:var(--teal);height:25px;margin:9px 0 3px;cursor:pointer}.hint{font-size:.78rem;color:var(--muted);line-height:1.65;margin:6px 0 12px}.hint strong{font-weight:650}.compact-details{border-top:1px solid var(--line);font-size:.8rem}.compact-details summary{padding:14px 0;font-weight:600}.target{border-top:1px solid var(--line);padding-top:22px;margin-top:22px}.target>span{font-size:.75rem;color:var(--muted);display:block}.target>strong{display:block;font-size:1.65rem;font-family:Georgia,serif;font-weight:500;margin:9px 0}.target p{font-size:.8rem;color:var(--muted);margin-bottom:0}.lab-main{min-width:0}.year-toolbar{display:flex;justify-content:space-between;gap:20px;align-items:center}.year-toolbar .eyebrow{margin-bottom:1px}.year-toolbar h3{font-family:Georgia,serif;font-weight:500;font-size:1.8rem;margin-bottom:10px}.button-group{display:flex;flex-wrap:wrap;gap:7px}.timeline-label{display:flex;justify-content:space-between;font-size:.75rem;color:var(--muted);margin-top:10px}.timeline-label output{font-weight:700}.range-ends{display:flex;justify-content:space-between;font-size:.67rem;color:var(--muted)}.metrics{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px;margin:25px 0}.core-metrics{grid-template-columns:repeat(4,minmax(0,1fr))}.metrics>div{border-left:2px solid var(--line);padding-left:13px}.metrics>div:last-child{border-color:var(--teal)}.metrics span{font-size:.76rem;color:var(--muted);display:block;line-height:1.6}.metrics strong{font-size:1.85rem;display:block;letter-spacing:-.035em;font-weight:600;font-variant-numeric:tabular-nums;margin:5px 0}.metrics small{color:var(--muted);font-size:.72rem;display:block}.explanation{padding:16px 20px;background:var(--wash);border-left:3px solid var(--teal);line-height:1.65;font-size:.91rem;margin:20px 0 26px}.explanation p:last-child{margin-bottom:0}.explanation strong{font-weight:700}.graph-heading{display:flex;align-items:center;justify-content:space-between;gap:16px;margin:22px 0 0}.graph-heading h3{margin-bottom:2px}.graph-heading .hint{margin-bottom:0}.segmented{display:flex;gap:0}.segmented button{border-radius:0;min-height:34px;padding:7px 9px;font-size:.72rem}.segmented button:first-child{border-radius:4px 0 0 4px}.segmented button:last-child{border-left:0;border-radius:0 4px 4px 0}.segmented button[aria-pressed=true]{background:var(--ink);border-color:var(--ink);color:white}svg{width:100%;height:auto;display:block;overflow:visible;margin-top:9px}svg text{font-family:ui-sans-serif,system-ui,sans-serif;fill:var(--muted);font-size:12px}svg .grid{stroke:#e3e9e6;stroke-width:1}svg .axis{stroke:#a8b8b3;stroke-width:1}svg .chart-line{fill:none;stroke-width:2.7;stroke-linecap:round;stroke-linejoin:round}svg .tick-text{font-variant-numeric:tabular-nums}svg .annotation{fill:var(--ink);font-size:12px;font-weight:650}.legend{display:flex;align-items:center;flex-wrap:wrap;gap:8px 22px;font-size:.73rem;color:var(--muted);line-height:1.6;margin:3px 0 13px}.legend>span{display:flex;align-items:center;gap:7px}.legend i{display:inline-block;font-style:normal;flex-shrink:0}.line{width:22px;border-top:3px solid}.line.dashed{border-top-style:dashed}.dot{height:9px;width:9px;border-radius:50%;background:currentColor}.teal{color:var(--teal)}.blue{color:var(--blue)}.rust{color:var(--rust)}.gold{color:var(--gold)}.gray{color:var(--gray)}.ink{color:var(--ink)}.readout{padding:10px 0 15px;font-size:.85rem;line-height:1.7;color:var(--muted)}.readout b{color:var(--ink)}.two-charts{display:grid;grid-template-columns:1fr 1fr;gap:25px;margin:20px 0}.two-charts h3{font-size:.9rem;margin-bottom:4px}.two-charts .graph-heading{margin:0}select{max-width:180px;font-size:.71rem;border:1px solid var(--line);padding:5px;background:var(--paper);color:var(--ink);border-radius:4px}.year-calculation{border-top:1px solid var(--line);border-bottom:1px solid var(--line);display:grid;grid-template-columns:245px 1fr;gap:38px;padding:25px 0;margin-top:30px}.year-calculation h3{font-size:1.15rem}.year-calculation ol{margin:0;padding-left:23px;display:grid;gap:8px;font-size:.88rem;line-height:1.6}.year-calculation li::marker{color:var(--teal);font-weight:700}.table-section{margin-top:25px}.table-scroll{overflow-x:auto;border-bottom:1px solid var(--line)}.table-section .table-scroll{margin-top:16px}.table-section .table-scroll.all-years{max-height:440px}.table-section .graph-heading{margin-top:0}table{width:100%;border-collapse:collapse;font-size:.84rem;line-height:1.6;font-variant-numeric:tabular-nums}th,td{padding:12px 10px;border-bottom:1px solid var(--line);text-align:right}thead th{font-weight:650;font-size:.76rem;color:var(--muted);position:sticky;top:0;background:var(--paper);z-index:1}th:first-child,td:first-child{text-align:left}tbody th{font-weight:600}caption{text-align:left;font-size:.82rem;font-weight:650;margin-bottom:12px}tr.selected{background:#eaf2ed}tr.limit{background:#f4efe1;border-top:2px solid #d9cda5}td button,th button{font:inherit;min-height:29px;padding:2px 3px;background:transparent;border:0;color:inherit;white-space:nowrap}td button:hover,th button:hover{background:#d8eae3;text-decoration:underline}tr.limit td,tr.limit th{font-weight:600}.cell-explanation{font-size:.85rem;padding:14px 0;color:var(--teal);min-height:55px}.lesson{border-top:1px solid var(--line);padding:0 0 1px;margin-top:14px}.lesson summary{font-weight:650;line-height:1.6;padding:17px 0;font-size:.95rem}.lesson p{font-size:.9rem;max-width:1000px;line-height:1.8}.lesson .hint{font-size:.78rem}.compare-table{margin:30px 0}.unit-note{font-size:.72rem;color:var(--muted)}.notation-note{padding:15px 19px;background:#f1f0e8;border-left:3px solid var(--gold);font-size:.88rem;line-height:1.7;margin:25px 0}.check{display:flex;align-items:flex-start;gap:9px;font-size:.83rem;line-height:1.6}.check input{accent-color:var(--teal);margin-top:4px}.account-equation{font-size:1.15rem;border-bottom:1px solid var(--line);padding-bottom:20px}.account-result{margin:25px 0}.account-result strong{display:block;font-size:4rem;font-family:Georgia,serif;font-weight:500;letter-spacing:-.06em;color:var(--teal)}.account-result p:last-child{font-size:.9rem;max-width:700px}.account-working{background:var(--wash);padding:18px 23px;font-size:.9rem;line-height:1.8;margin-top:16px}.account-working p{margin:0}.explain-columns{display:grid;grid-template-columns:1fr 1fr;gap:45px;border-top:1px solid var(--line);margin-top:35px;padding-top:25px}.explain-columns p{font-size:.88rem}.study-layout{display:grid;grid-template-columns:1fr 1fr;gap:48px;margin-top:30px}.glossary th{text-align:left;font-family:Georgia,serif;font-size:1rem;white-space:nowrap;width:90px;vertical-align:top}.glossary td{text-align:left;font-size:.82rem}.study-layout .lesson{margin-top:0}.study-layout .lesson summary{font-size:.86rem}.study-layout .lesson p{font-size:.83rem}.practice{margin-top:38px;padding-top:25px;border-top:1px solid var(--line)}.practice-grid{display:grid;grid-template-columns:1fr 1fr;gap:25px 38px}.question{border-top:1px solid var(--line);padding-top:18px;min-width:0}.question h4{font-size:.9rem;line-height:1.6;margin:0 0 12px}.answer-options{display:flex;flex-direction:column;align-items:stretch;gap:6px}.answer-options button{text-align:left;font-size:.8rem;line-height:1.6;min-height:40px}.answer-options button.correct{border-color:var(--teal);background:#e3f1e9}.answer-options button.incorrect{border-color:var(--rust);background:#fbede6}.question .feedback{font-size:.81rem;line-height:1.7;margin-top:12px;color:var(--muted)}footer{border-top:1px solid var(--line);margin-top:45px;padding-top:24px;color:var(--muted);font-size:.74rem}footer p{max-width:900px;margin-bottom:12px}footer nav{display:flex;gap:25px;flex-wrap:wrap;margin:10px 0 15px}.notice{padding:15px;background:#f4e7da}.skip{position:absolute;top:-80px;left:15px;background:var(--paper);padding:10px;z-index:10}.skip:focus{top:10px}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
@media(min-width:1500px){main{padding:30px 60px}}
@media(max-width:1050px){main{padding:24px 30px}.hero{gap:30px}.lab-layout{grid-template-columns:210px 1fr;gap:25px}.controls{padding-right:20px}.year-calculation{grid-template-columns:210px 1fr;gap:25px}.chapters button{font-size:.76rem}.hero-equation p{font-size:1.75rem}.graph-heading{flex-wrap:wrap}.metrics{gap:10px}.metrics strong{font-size:1.6rem}}
@media(max-width:780px){main{padding:20px}.site-line{gap:12px;flex-wrap:wrap}.site-line>span:nth-child(2){order:3;flex-basis:100%;font-size:.62rem}.chapter-tag{margin-left:auto}.hero{grid-template-columns:1fr;padding:30px 0 22px;gap:20px}.hero-equation{padding:0;border:0}.hero-equation>span,.hero-equation small{display:none}.hero-equation p{font-size:1.4rem;margin:0}.intro{font-size:.95rem}.chapters{display:flex;overflow-x:auto;gap:20px;margin-bottom:28px;scrollbar-width:thin}.chapters button{flex:0 0 auto;margin:0;max-width:170px;font-size:.8rem;padding:13px 0;min-width:125px}.chapters button>span{display:none}.panel-heading{align-items:flex-start;flex-direction:column;gap:10px}.panel-heading p:last-child{font-size:.88rem}.panel-heading .quiet{padding-left:0}.lab-layout{grid-template-columns:1fr;gap:25px}.controls{border-right:0;border-bottom:1px solid var(--line);padding:0 0 20px;display:grid;grid-template-columns:1fr 1fr;gap:0 25px}.controls>h3,.controls>.large,.controls>.hint,.controls>.target,.controls>.compact-details,.controls>.wide,.controls>.check{grid-column:1/-1}.controls>.large{margin:0 0 5px}.controls>h3{margin-bottom:8px}.control{margin:15px 0}.controls .target{display:none}.year-calculation{grid-template-columns:1fr;gap:10px}.year-calculation>div>.hint{margin-bottom:0}.explain-columns,.study-layout{grid-template-columns:1fr;gap:25px}.study-layout .lesson p{max-width:none}.two-charts{gap:15px}.two-charts select{max-width:140px}.scenario-row{margin-bottom:22px}.scenario-row>span{flex-basis:100%}.scenario-row button{font-size:.76rem}.practice-grid{grid-template-columns:1fr}.metrics span{font-size:.7rem}.metrics strong{font-size:1.6rem}.metrics{gap:10px}.metrics>div{padding-left:8px}.year-toolbar{gap:12px}.button-group{gap:5px}.year-toolbar button{font-size:.75rem;padding:8px 10px}.explanation{font-size:.85rem;padding:14px 16px}.notation-note{font-size:.83rem}.account-result strong{font-size:3.5rem}}
@media(max-width:500px){main{padding:19px 16px}.hero h1{font-size:3.2rem}.eyebrow{font-size:.6rem}.controls{gap:0 18px}.controls .control label{font-size:.77rem}.core-metrics{grid-template-columns:repeat(2,1fr);gap:16px}.metrics:not(.core-metrics){grid-template-columns:1fr 1fr}.metrics:not(.core-metrics)>div:last-child{grid-column:1/-1}.year-toolbar{align-items:flex-start}.year-toolbar .button-group{justify-content:flex-end}.year-toolbar .eyebrow{max-width:110px}.year-toolbar h3{font-size:1.6rem}.year-toolbar #core-back{display:none}.two-charts{grid-template-columns:1fr;gap:23px}.graph-heading{gap:8px}.graph-heading h3{font-size:.94rem}.legend{font-size:.68rem;gap:6px 14px}svg text{font-size:13px}.table-section th,.table-section td{padding:9px 7px}.table-section table{min-width:570px}.table-section .button-group{margin-top:6px}.compare-table table{min-width:500px}.table-section .graph-heading{margin-top:5px}.cell-explanation{font-size:.8rem}.notation-note{padding:13px}.study-layout .table-scroll table{min-width:0}.glossary th{width:63px}.glossary td{padding:10px 6px}footer nav{gap:12px}.account-working{padding:15px}.hero-equation p{font-size:1.3rem}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important}}
@media print{body,main{background:white}main{max-width:none;padding:0}.hero{padding-top:0}.chapters,.controls,.scenario-row,.button-group,.segmented,input,footer,.chapter-tag{display:none!important}.lab-layout{grid-template-columns:1fr}.panel-heading{margin-top:25px}.explanation{break-inside:avoid}svg{break-inside:avoid}.year-calculation{grid-template-columns:1fr}.table-section .table-scroll{max-height:none}.panel:not([hidden]) .lesson>p{display:block}.site-line{margin-bottom:20px}}
