@font-face{font-family:BookThai;src:local('Leelawadee UI')}@font-face{font-family:BookMath;src:local('Cambria Math')}
:root{--bg:#f7f6f0;--paper:#fffefa;--ink:#243c33;--muted:#68746b;--line:#dce0d5;--green:#285443;--soft:#eaf0e6;--gold:#ad743d;--warning:#fbefdb;--blue:#eaf0f5;--body-size:18px;color-scheme:light}
:root[data-theme=dark]{--bg:#17221e;--paper:#1e2c25;--ink:#e2e9de;--muted:#a8b8ac;--line:#3c4b40;--green:#a4d2b5;--soft:#2c3e31;--gold:#e6b780;--warning:#433723;--blue:#263a46;color-scheme:dark}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:105px}body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.75 BookThai,'Leelawadee UI',Tahoma,sans-serif}button,input{font:inherit}button,a,input{-webkit-tap-highlight-color:transparent}a{color:inherit;text-decoration:none}button{cursor:pointer}button:disabled{cursor:default;opacity:.5}a:hover{color:var(--gold)}button:focus-visible,a:focus-visible,input:focus-visible,summary:focus-visible,[tabindex]:focus-visible{outline:3px solid var(--gold);outline-offset:4px}button{color:inherit}::selection{background:#d8e4c3;color:#243c33}[hidden]{display:none!important}.skip-link{position:fixed;top:-100px;left:16px;padding:12px;background:var(--paper);z-index:100}.skip-link:focus{top:10px}.topbar{height:96px;max-width:1320px;margin:auto;padding:0 48px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line)}.brand{display:flex;gap:13px;align-items:center;font-size:23px;line-height:1.2;font-weight:600}.brand-mark{font:italic 42px Georgia,serif;background:var(--green);color:var(--bg);border-radius:13px;width:52px;height:52px;text-align:center;line-height:48px}.brand-mark span{color:#d5aa72}.brand small{display:block;font-size:9px;letter-spacing:1.6px;margin-top:7px;font-weight:400}.topbar nav{display:flex;gap:30px;align-items:center;font-size:13px}.icon-button{border:1px solid var(--line);border-radius:50%;width:39px;height:39px;background:transparent;font-size:22px}.eyebrow{font-size:11px;letter-spacing:1.7px;font-weight:700;color:var(--muted);display:flex;align-items:center;gap:9px}.status-dot{width:7px;height:7px;border-radius:50%;background:var(--green)}.hero{max-width:1224px;margin:auto;display:grid;grid-template-columns:1.12fr 1fr;align-items:center;gap:25px;padding:72px 0 56px}.hero h1{font-size:clamp(32px,3.3vw,46px);line-height:1.5;letter-spacing:-1.4px;font-weight:600;margin:22px 0 20px}.hero h1 span{display:block;color:var(--green)}.hero-copy>p{color:var(--muted);font-size:17px;line-height:1.9}.hero-art{width:100%;transform:rotate(-3deg)}.hero-actions,.chapter-actions{display:flex;gap:24px;align-items:center;flex-wrap:wrap;margin-top:28px}.button{display:inline-flex;align-items:center;justify-content:center;gap:24px;background:var(--green);color:var(--bg);border:1px solid var(--green);border-radius:8px;padding:12px 24px;font-size:14px;font-weight:600}.button:hover{background:var(--ink);color:var(--bg)}.button.secondary{background:transparent;color:var(--ink);border-color:var(--line)}.button.small{font-size:12px;padding:8px 14px;gap:9px}.text-link{font-size:13px;border-bottom:1px solid var(--line);padding-bottom:3px}.hero-stats{display:flex;gap:40px;margin-top:40px}.hero-stats>div{display:flex;align-items:center;gap:12px}.hero-stats b{font:32px Georgia,serif}.hero-stats span{font-size:11px;color:var(--muted)}.learning-note{max-width:1224px;margin:0 auto 68px;padding:22px 28px;background:var(--soft);border:1px solid var(--line);border-radius:12px;display:flex;align-items:center;gap:20px}.note-icon{font-size:32px}.learning-note strong{font-size:15px}.learning-note p{font-size:13px;color:var(--muted);margin:3px 0}.edition-tag{margin-left:auto;text-align:right;font-size:10px;letter-spacing:1px;color:var(--muted)}.chapter-section,.reading-guide{max-width:1224px;margin:auto}.section-heading{display:flex;align-items:center;justify-content:space-between;margin-bottom:28px;gap:20px}h2{font-size:28px;font-weight:600;margin:8px 0 0}.search-box{border:1px solid var(--line);background:var(--paper);padding:9px 13px;display:flex;align-items:center;gap:10px;border-radius:8px;min-width:315px}.search-box>span{font-size:24px}.search-box input{background:transparent;border:0;outline:0;color:var(--ink);font-size:12px;min-width:0;width:100%}.search-box kbd{font-size:11px;border:1px solid var(--line);padding:0 5px;border-radius:4px;color:var(--muted)}.chapter-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:22px}.chapter-card{padding:25px 26px 0;border:1px solid var(--line);border-radius:14px;background:var(--paper);display:flex;flex-direction:column;transition:transform .2s,box-shadow .2s}.chapter-card:hover{transform:translateY(-4px);box-shadow:0 10px 30px #1735200a}.card-top{display:flex;justify-content:space-between;align-items:center}.card-number{font:27px Georgia,serif;color:var(--muted)}.card-status{font-size:10px;display:inline-flex;align-items:center;gap:7px;color:var(--muted)}.card-status:before{content:'';width:5px;height:5px;border-radius:50%;background:#a5b29c}.card-status.visited{color:var(--green)}.card-status.visited:before{background:var(--green)}.card-formula{background:var(--soft);border-radius:9px;text-align:center;padding:17px 8px;margin:20px 0 21px;font:italic 25px Georgia,'Cambria Math',serif;color:var(--green)}.chapter-card:nth-child(2n) .card-formula{background:var(--warning);color:var(--gold)}.chapter-card:nth-child(3n) .card-formula{background:var(--blue);color:var(--ink)}.card-title h3{font-size:21px;line-height:1.6;margin:0 0 5px;font-weight:600}.card-english{font-size:10px;color:var(--muted);margin:0 0 15px}.card-description{font-size:13px;line-height:1.85;color:var(--muted);margin:0 0 19px}.card-meta{display:flex;gap:20px;font-size:10px;color:var(--muted);margin-top:auto;margin-bottom:20px}.card-meta span:before{content:'·';margin-right:7px}.card-links{display:flex;gap:17px;border-top:1px solid var(--line);padding:16px 0;font-size:11px;align-items:center}.card-links>a:first-child{margin-right:auto;font-weight:700}.card-links span{margin-left:8px}.reading-guide{padding:70px 0}.reading-guide h2{font-size:25px}.reading-guide>div:last-child{display:grid;grid-template-columns:repeat(3,1fr);gap:40px}.reading-guide p{font-size:13px;color:var(--muted)}.reading-guide strong{display:inline-block;color:var(--ink);font-weight:600;margin-bottom:8px}.site-footer{border-top:1px solid var(--line);max-width:1224px;margin:auto;display:flex;justify-content:space-between;gap:20px;padding:26px 0;font-size:10px;color:var(--muted)}.search-results{border:1px solid var(--line);background:var(--paper);padding:16px;border-radius:9px;margin-bottom:22px;max-height:410px;overflow:auto}.search-results a{display:block;padding:10px 12px;border-bottom:1px solid var(--line);font-size:14px}.search-results small{color:var(--muted);margin-right:10px}.search-results p{margin:0 12px 8px;font-size:12px;color:var(--muted)}.empty-search{padding:32px;text-align:center}
/* Reading pages */
.reader .topbar{max-width:none;padding:0 40px;height:80px;background:var(--bg);position:sticky;top:0;z-index:20}.reader-layout{display:grid;grid-template-columns:280px minmax(0,930px);max-width:1310px;margin:auto;gap:60px;padding:0 30px}.sidebar{position:sticky;top:80px;align-self:start;height:calc(100vh - 80px);overflow:auto;padding:30px 20px 30px 0;scrollbar-width:thin;border-right:1px solid var(--line)}.back-link{font-size:12px;color:var(--muted)}.chapter-label{font-size:10px;letter-spacing:1.5px;color:var(--gold);font-weight:700;margin-top:30px}.sidebar-title{font-size:18px;font-weight:600;margin:9px 0 25px;line-height:1.6}.toc-panel>summary{font-size:12px;font-weight:700;margin-bottom:14px;cursor:pointer}.toc-panel nav{display:flex;flex-direction:column;gap:2px}.toc-panel nav a{font-size:12px;color:var(--muted);padding:7px 10px;border-left:2px solid transparent;border-radius:0 5px 5px 0;line-height:1.7}.toc-panel nav a:hover,.toc-panel nav a.active{background:var(--soft);border-color:var(--green);color:var(--ink)}.sidebar-other{display:block;font-size:12px;font-weight:600;border-top:1px solid var(--line);margin-top:24px;padding-top:18px}.reader-main{min-width:0;padding-bottom:50px}.reader-toolbar{display:flex;justify-content:space-between;align-items:center;padding:22px 0;border-bottom:1px solid var(--line);font-size:11px;color:var(--muted)}.reader-toolbar>div{display:flex;gap:6px}.reader-toolbar button{background:transparent;border:1px solid var(--line);border-radius:5px;padding:3px 10px;font-size:12px}.chapter-header{position:relative;padding:42px 0 35px}.chapter-number{display:block;font:74px/1 Georgia,serif;color:var(--gold);margin:25px 0 15px}.chapter-header h1{font-size:35px;line-height:1.5;margin:0 0 8px;font-weight:600;max-width:780px}.english-title{font:17px Georgia,serif;color:var(--muted);margin:0 0 20px}.chapter-header>p:not(.english-title){font-size:15px;color:var(--muted);max-width:700px}.chapter-actions{gap:12px;margin-top:23px}.book-content{font-size:var(--body-size);line-height:1.95;overflow-wrap:anywhere}.book-content p{margin:1em 0}.book-content h2{font-size:1.42em;line-height:1.65;padding-top:35px;margin-top:45px;margin-bottom:22px;border-top:1px solid var(--line);scroll-margin-top:95px}.book-content h3{font-size:1.12em;margin:30px 0 15px;line-height:1.7}.book-content h4{font-size:1em;margin:25px 0 12px}.book-content strong{font-weight:700;color:var(--green)}.book-content ul,.book-content ol{padding-left:28px}.book-content li{padding-left:5px;margin:9px 0}.callout{border:1px solid var(--line);border-left:4px solid var(--green);background:var(--soft);border-radius:0 10px 10px 0;margin:25px 0;padding:20px 24px;font-size:.94em}.callout p:first-child{margin-top:0}.callout p:last-child{margin-bottom:0}.callout-title{font-weight:700;margin-bottom:8px;color:var(--green)}.callout.warning{background:var(--warning);border-left-color:var(--gold)}.callout.math-note{background:var(--blue)}.equation{border:1px solid var(--line);border-radius:8px;padding:20px 24px;background:var(--paper);overflow-x:auto;overflow-y:hidden;max-width:100%;scrollbar-width:thin}.book-content math{font-family:BookMath,'Cambria Math',math;font-size:1.1em}.book-content math[display=block]{margin:.3em 0;min-width:min-content}.book-content math[display=inline]{white-space:nowrap}.book-content annotation{display:none}.source-note{font-size:.7em;line-height:1.8;color:var(--muted);padding-left:13px;border-left:2px solid var(--line)}.key-point{padding:17px 21px;background:var(--soft);border-radius:7px}.book-content figure{margin:32px 0;border:1px solid var(--line);border-radius:12px;background:#fff;padding:20px;overflow:hidden}.book-content figure img{display:block;max-width:100%;height:auto;margin:auto;cursor:zoom-in;border-radius:4px}.book-content figcaption{font-size:12px;line-height:1.8;color:#56645a;text-align:center;margin-top:15px}.book-content figcaption math{font-size:1em}.table-scroll{overflow-x:auto;max-width:100%;margin:26px 0;border:1px solid var(--line);border-radius:9px}.book-content table{border-collapse:collapse;width:100%;font-size:.83em;background:var(--paper)}.book-content th,.book-content td{text-align:left;padding:12px 16px;border-bottom:1px solid var(--line);vertical-align:top;min-width:100px}.book-content th{background:var(--soft);font-weight:600}.book-content td p:first-child{margin-top:0}.book-content td p:last-child{margin-bottom:0}.book-content table tr:last-child td{border-bottom:0}.book-content col{width:auto!important}.solution{margin:20px 0;border:1px solid var(--line);border-radius:9px;padding:0 24px;background:var(--paper);scroll-margin-top:100px}.solution summary{cursor:pointer;font-size:1.05em;font-weight:600;padding:20px 0;color:var(--green)}.solution[open]{padding-bottom:22px}.solution[open] summary{border-bottom:1px solid var(--line);margin-bottom:20px}.chapter-pagination{border-top:1px solid var(--line);margin-top:50px;padding-top:25px;display:flex;justify-content:space-between;gap:12px;font-size:13px}.reading-progress{position:fixed;top:79px;height:3px;left:0;right:0;z-index:30}.reading-progress span{display:block;height:100%;background:var(--gold);width:0}.reader .site-footer{padding-left:30px;padding-right:30px}.simulation{padding:25px;background:var(--soft);border:1px solid var(--line);border-radius:12px;scroll-margin-top:100px}.simulation h2{font-size:23px;line-height:1.6;margin-top:8px}.simulation>p{font-size:13px;color:var(--muted);margin:10px 0 22px}.lab-grid{display:grid;grid-template-columns:minmax(0,1.65fr) minmax(180px,1fr);gap:23px}.lab-canvas{background:#fcfcf7;width:100%;border:1px solid var(--line);border-radius:8px;display:block}.lab-canvas text{font-family:Tahoma,sans-serif}.lab-actions{display:flex;flex-wrap:wrap;gap:8px;margin-top:12px}.lab-controls label{display:grid;grid-template-columns:1fr auto;font-size:11px;margin-bottom:15px;gap:4px}.lab-controls output{font-variant-numeric:tabular-nums;font-weight:600}.lab-controls input{width:100%;grid-column:1/-1;accent-color:var(--green)}.lab-values{font-size:12px;border-top:1px solid var(--line);padding-top:12px;font-variant-numeric:tabular-nums}.lab-values div{display:flex;justify-content:space-between;gap:8px;padding:3px 0}.simulation .assumptions{font-size:11px;border-top:1px solid var(--line);padding-top:15px;margin:20px 0 0;line-height:1.8}.simulation .assumptions strong{color:var(--ink)}#image-dialog{border:1px solid var(--line);border-radius:12px;padding:20px;max-width:96vw;max-height:94vh;background:var(--paper);color:var(--ink)}#image-dialog::backdrop{background:#0c211ed9}#image-dialog img{display:block;max-width:90vw;max-height:74vh;object-fit:contain;background:white;margin:auto}#image-dialog button{display:block;margin-left:auto;border:1px solid var(--line);background:var(--soft);border-radius:5px;padding:5px 15px;margin-bottom:15px}#image-dialog p{font-size:13px;text-align:center;max-width:900px}
.math-inline{white-space:nowrap;display:inline-block;max-width:100%;overflow-x:auto;overflow-y:hidden;vertical-align:middle;padding:3px 1px;scrollbar-width:thin}.math-display{display:block;min-width:min-content}.math-tex mjx-container{font-size:108%!important}.math-tex mjx-container[display=true]{margin:.25em 0!important}.equation mjx-container>svg{max-width:none!important}.book-content h2 .math-tex mjx-container,.book-content h3 .math-tex mjx-container{font-size:100%!important}mjx-container[jax=SVG]{direction:ltr;text-indent:0}mjx-container[jax=SVG] svg{overflow:visible}.book-content figure mjx-container{color:#243c33}
@media(min-width:1500px){.reader-layout{gap:80px;max-width:1410px;grid-template-columns:290px minmax(0,930px)}}
@media(max-width:1320px){.hero,.chapter-section,.reading-guide{margin-left:48px;margin-right:48px}.learning-note{margin-left:48px;margin-right:48px}.site-footer{margin-left:48px;margin-right:48px}.reader-layout{gap:35px;grid-template-columns:240px minmax(0,1fr)}}
@media(max-width:1050px){.chapter-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.hero{padding-top:45px;gap:0}.hero h1{font-size:35px}.hero-stats{gap:22px}.hero-stats>div{display:block}.hero-stats span{display:block}.hero-art{min-width:0}.reader-layout{grid-template-columns:205px minmax(0,1fr);gap:25px;padding:0 24px}.lab-grid{grid-template-columns:1fr}.lab-controls{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}.lab-values{grid-column:1/-1}.chapter-header h1{font-size:30px}}
@media(max-width:760px){.topbar,.reader .topbar{height:78px;padding:0 22px}.brand{font-size:20px}.brand-mark{width:44px;height:44px;font-size:35px;line-height:41px}.brand small{font-size:8px}.topbar nav{gap:15px}.topbar nav>a{font-size:11px}.hero,.chapter-section,.reading-guide{margin-left:22px;margin-right:22px}.hero{grid-template-columns:1fr;padding-top:35px;padding-bottom:30px}.hero h1{font-size:37px;letter-spacing:-.8px}.hero-copy>p{font-size:15px}.hero-art{max-width:430px;margin:15px auto 0;max-height:270px}.hero-stats{gap:32px;margin-top:28px}.hero-stats>div{display:flex;gap:9px}.hero-stats b{font-size:26px}.hero-stats span{font-size:9px}.hero-actions{gap:19px}.button{padding:11px 19px;font-size:13px}.learning-note{margin:0 22px 40px;padding:18px;gap:13px}.learning-note strong{font-size:13px}.learning-note p{font-size:11px}.edition-tag{display:none}.section-heading{display:block}.section-heading h2{font-size:25px}.search-box{margin-top:22px;min-width:0}.chapter-grid{gap:16px}.chapter-card{padding:19px 19px 0}.card-title h3{font-size:19px}.card-links{gap:10px;flex-wrap:wrap}.card-english{font-size:9px}.card-description{font-size:12px}.reading-guide{padding:45px 0}.reading-guide>div:last-child{grid-template-columns:1fr;gap:4px}.site-footer{margin:0 22px;flex-direction:column;gap:5px}.reader-layout{display:block;padding:0 20px}.sidebar{position:static;height:auto;border:0;padding:20px 0 0}.chapter-label,.sidebar-title,.sidebar-other{display:none}.toc-panel{margin-top:14px;padding:12px 16px;border:1px solid var(--line);border-radius:8px;background:var(--paper)}.toc-panel>summary{margin:0}.toc-panel nav{max-height:260px;overflow:auto;margin-top:12px}.toc-panel:not([open]) nav{display:none}.reader-toolbar{padding:16px 0}.chapter-header{padding-top:30px}.chapter-header h1{font-size:29px}.chapter-number{font-size:60px;margin-top:20px}.english-title{font-size:14px}.chapter-actions{gap:9px}.chapter-actions .text-link{font-size:11px}.book-content{font-size:calc(var(--body-size) - 1px)}.book-content h2{font-size:1.3em}.callout{padding:17px 18px}.equation{padding:16px 13px}.book-content figure{padding:12px}.book-content td,.book-content th{padding:10px 12px}.simulation{padding:19px 15px}.simulation h2{font-size:21px}.simulation .eyebrow{font-size:9px;letter-spacing:1px}.lab-controls{gap:10px}.solution{padding:0 17px}.chapter-pagination{font-size:11px}.reader .site-footer{padding-left:0;padding-right:0}.reading-progress{top:77px}}
@media(max-width:480px){.chapter-grid{grid-template-columns:1fr}.chapter-card{padding:23px 24px 0}.card-title h3{font-size:22px}.card-english{font-size:11px}.card-description{font-size:14px}.card-meta{font-size:11px}.card-links{font-size:12px}.card-formula{padding:20px}.hero h1{font-size:33px}.hero-stats{gap:22px}.hero-stats>div{display:block}.hero-stats span{margin-top:2px}.hero-art{max-height:245px}.lab-controls{grid-template-columns:1fr}.chapter-header h1{font-size:27px}.topbar nav>a{display:none}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{transition:none!important;animation:none!important}}
@media print{:root,:root[data-theme=dark]{--bg:white;--paper:white;--ink:#111;--muted:#555;--line:#ccc;--green:#234638;--soft:#f1f4ee;--gold:#784d1c;color-scheme:light}.topbar,.sidebar,.reader-toolbar,.chapter-actions,.simulation,.site-footer,.chapter-pagination,.reading-progress,.skip-link,#image-dialog{display:none!important}.reader-layout{display:block;max-width:none;padding:0;margin:0}.reader-main{padding:0}.chapter-header{padding:0}.chapter-number{font-size:40px;margin:0}.chapter-header h1{font-size:25px}.book-content{font-size:11pt;line-height:1.6}.book-content h2{font-size:16pt;break-after:avoid}.book-content figure,.callout{break-inside:avoid}.equation{overflow:visible;padding:10px}.book-content figure img{max-height:85mm;width:auto}.table-scroll{overflow:visible}.solution{border:0;padding:0}.solution summary{font-size:14pt;break-after:avoid}.hero-art{max-height:250px}.chapter-grid{grid-template-columns:repeat(2,1fr)}@page{margin:18mm}}