:root{--paper:#f4f2eb;--ink:#172e2b;--jade:#426b5f;--line:#c3c8bf;--night:#071119;--copper:#bc825c;--serif:"Songti SC","Noto Serif CJK SC","STSong",serif;--sans:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif;color-scheme:light;font-family:var(--sans);color:var(--ink);background:var(--paper);font-synthesis:none}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:72px}body{margin:0}button,input,textarea{font:inherit}button,a,input,textarea{-webkit-tap-highlight-color:transparent}button,a{touch-action:manipulation}button{cursor:pointer;color:inherit}button{background:none;border:0}a{color:inherit;text-underline-offset:5px}button:focus-visible,a:focus-visible,input:focus-visible,textarea:focus-visible,summary:focus-visible{outline:2px solid var(--copper);outline-offset:5px}p{margin:0 0 1.25em}h1,h2,h3{margin:0;font-weight:500}h1,h2{font-family:var(--serif)}h2{font-size:clamp(32px,8.5vw,46px);line-height:1.32;letter-spacing:-.045em;margin:0 0 28px}h3{font-size:23px;margin:36px 0 16px}small,.caption{font-size:13px;line-height:1.75;color:#526760}.caption{margin-top:18px}.skip{position:fixed;left:15px;top:-100px;padding:12px;background:var(--paper);z-index:20}.skip:focus{top:10px}
.masthead{height:72px;padding:0 24px;display:flex;align-items:center;justify-content:space-between;position:absolute;top:0;left:0;right:0;z-index:5;color:var(--paper)}.masthead:after{content:"";position:absolute;bottom:0;left:24px;right:24px;height:1px;background:currentColor;opacity:.3}.brand{font-family:Georgia,serif;font-size:23px;text-decoration:none;letter-spacing:.025em}.masthead button{font-size:14px;min-height:44px;min-width:44px}.reading .masthead{position:fixed;background:var(--paper);color:var(--ink)}
.cover{position:relative;height:100svh;min-height:640px;background:var(--night);color:var(--paper);overflow:hidden;isolation:isolate}.cover canvas{position:absolute;inset:0;width:100%;height:100%;z-index:-1}.cover-copy{position:absolute;top:112px;left:24px;right:24px}.cover h1{font-size:clamp(43px,11.8vw,76px);line-height:1.22;letter-spacing:-.035em;text-shadow:0 2px 25px #071119;animation:arrive 1.2s ease-out both}.cover-copy p{font-family:var(--serif);font-size:clamp(15px,4.25vw,23px);margin-top:18px;animation:arrive 1.2s .12s ease-out both}.cover-bottom{position:absolute;bottom:max(30px,env(safe-area-inset-bottom));left:24px;right:24px;display:flex;justify-content:space-between;align-items:center;border-bottom:1px solid #aeb9b16b;padding:0 0 18px;font-family:Georgia,var(--serif);font-size:17px}.start{display:flex;gap:12px;align-items:center;text-decoration:none;font-family:var(--serif);font-size:21px}.arrow{width:54px;height:54px;display:grid;place-items:center;border-radius:50%;background:var(--copper);color:var(--night);font-family:var(--sans);font-size:30px;transition:transform .2s}.start:hover .arrow{transform:rotate(45deg)}.motion{position:absolute;right:24px;bottom:126px;font-size:12px;color:#dce4df;border-bottom:1px solid #7c8b8f;min-height:44px;padding:6px 0}.cover.paused *{animation-play-state:paused!important}
article{max-width:690px;margin:auto;padding:0 24px 90px;font-size:18px;line-height:1.85}article>section{padding:54px 0 18px;border-bottom:1px solid var(--line);scroll-margin-top:0}article>section:last-child{border:0}.section-meta{font-size:12px;letter-spacing:.05em;color:var(--jade);display:flex;justify-content:space-between;margin-bottom:24px}.lead{font-size:21px;line-height:1.75}.reading-tip{font-size:13px;color:var(--jade);line-height:1.8;border-left:2px solid var(--copper);padding-left:12px}.reading-tip button{font-size:13px;text-decoration:underline;padding:8px 0;display:inline-block}.term{display:inline;padding:0;border:0;font:inherit;color:inherit;text-decoration:underline;text-decoration-color:#768f84;text-decoration-thickness:1px;text-underline-offset:4px;border-radius:0}.term:hover{color:var(--jade);background:#dfe6db}.citation{font-size:12px;vertical-align:super;margin-left:3px;text-decoration:none;padding:5px}details{margin:20px 0}summary{cursor:pointer;line-height:1.7;font-size:15px;padding:12px 0;min-height:44px}details p,details ol{font-size:16px;line-height:1.85}details ol{padding-left:22px}.study-plan{border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.flow-figure{margin:32px 0 26px;padding:24px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}figcaption{font-size:12px;color:var(--jade);display:flex;gap:18px}.flow-body{display:flex;align-items:center;justify-content:center;padding:28px 0 6px;gap:22px}.flow-chain{width:57%;max-width:235px}.flow-chain button{font-family:Georgia,var(--serif);font-size:23px;border:1px solid var(--jade);width:100%;padding:10px 5px;line-height:1.3;transition:background .15s}.flow-chain button:hover{background:#e3e7dd}.flow-chain small{display:block;font-size:13px;color:inherit}.flow-chain button.filled{background:#193e36;color:var(--paper)}.connector{display:block;position:relative;text-align:center;line-height:34px;color:var(--jade);font-size:23px}.connector span{font-size:12px;position:absolute;left:58%;white-space:nowrap}.context{position:relative;width:34%;font-size:12px;padding-left:10px}.context button{font-size:14px;padding:8px 0;border-bottom:1px solid var(--line)}.context p{margin:10px 0;line-height:1.8}.context small{font-size:11px}.context-bracket{position:absolute;left:-12px;top:-64px;bottom:-64px;width:14px;border-left:1px dashed var(--jade);border-radius:50%}.context-bracket:before,.context-bracket:after{content:"";width:9px;height:1px;background:var(--jade);position:absolute;left:0}.context-bracket:before{top:0}.context-bracket:after{bottom:0}blockquote{font-family:var(--serif);font-size:27px;line-height:1.6;margin:38px 0;padding-left:18px;border-left:2px solid var(--copper)}
.atlas{margin:30px 0}.atlas details{border-top:1px solid var(--line);margin:0}.atlas details:last-child{border-bottom:1px solid var(--line)}.atlas summary{list-style:none;position:relative;padding:18px 26px 18px 34px;font-size:20px;font-family:var(--serif)}.atlas summary::-webkit-details-marker{display:none}.atlas summary:after{content:"+";font-family:var(--sans);position:absolute;right:2px;top:21px;font-size:20px}.atlas details[open] summary:after{content:"−"}.atlas summary>span{position:absolute;left:0;top:24px;font-size:12px;font-family:Georgia,serif;color:var(--jade)}.atlas summary small{display:block;font-family:var(--sans);font-size:12px;margin-top:4px}.atlas details p{padding-left:34px;margin:0 0 20px}.atlas-example{color:var(--jade)}
.experiment{background:#e7e9df;padding:24px;margin:30px -8px}.minor{font-size:12px;letter-spacing:.06em;color:var(--jade)}.experiment h3{font-family:var(--serif);font-size:26px;margin:15px 0}.experiment>p{font-size:15px}.experiment label{display:flex;align-items:center;justify-content:space-between;font-size:14px;margin-top:20px}.experiment input{display:block;width:100%;height:38px;accent-color:var(--jade);cursor:pointer}.signal-result{display:flex;justify-content:space-between;align-items:baseline;padding-top:15px;border-top:1px solid var(--line);margin-top:18px;font-size:14px}.signal-result output{font-family:Georgia,serif;font-size:48px;line-height:1.5}.signal-track{height:4px;background:#c9cfc3}.signal-track span{display:block;height:100%;background:var(--jade);width:30%;transition:width .15s}.text-action{padding:10px 0;min-height:44px;text-decoration:underline;text-underline-offset:5px;font-size:14px}.loop{list-style:none;padding:0;margin:30px 0}.loop li{display:grid;grid-template-columns:35px 1fr;gap:18px;border-top:1px solid var(--line);padding:18px 0}.loop li>span{font-family:Georgia,serif;font-size:31px;color:var(--jade);line-height:1.3}.loop h3{font-size:17px;margin:0 0 9px}.loop p{font-size:16px;margin:0}
#worksheet label{font-size:16px;display:block;margin:24px 0 10px}textarea{width:100%;resize:vertical;background:transparent;border:1px solid #9eada2;border-radius:0;padding:12px;font-size:16px;line-height:1.7;min-height:93px;color:var(--ink)}textarea::placeholder{color:#6b7770;font-size:14px}.form-actions{display:flex;gap:15px;flex-wrap:wrap;align-items:center;margin:22px 0}.form-actions span{font-size:12px;color:var(--jade)}.solid{display:inline-block;min-height:48px;padding:12px 20px;background:var(--ink);color:var(--paper);font-size:15px;border:1px solid var(--ink);transition:background .2s}.solid:hover{background:var(--jade)}.answer-example{border-top:1px solid var(--line)}fieldset{border:0;border-bottom:1px solid var(--line);padding:18px 0 24px;margin:0 0 25px;min-width:0}legend{font-size:18px;line-height:1.75;padding:0;width:100%}legend span{font-family:Georgia,serif;color:var(--jade);display:block;font-size:14px;margin-bottom:8px}fieldset label{display:flex;align-items:flex-start;gap:12px;min-height:48px;font-size:15px;padding:9px 0}input[type=radio]{flex-shrink:0;width:19px;height:19px;accent-color:var(--jade);margin:4px 0 0}.feedback{font-size:14px;padding:14px;border-left:2px solid var(--jade);background:#e5e9df;margin:14px 0 0}.feedback.wrong{border-color:var(--copper);background:#eee3d7}#quiz-result{font-size:15px;margin-top:15px}.references ol{padding-left:21px}.references li{font-size:15px;padding:12px 0}.references li p{font-size:13px;margin:8px 0 0;color:#526760}.references li a{overflow-wrap:anywhere}.finish{padding-top:60px;padding-bottom:55px}.finish h2{font-size:31px;margin-top:20px}.finish>a{font-size:14px}.finish [role=status]{font-size:14px;margin-top:15px}
.reading-dock{display:none;position:fixed;bottom:0;left:0;right:0;background:var(--paper);z-index:6;padding:6px 24px max(6px,env(safe-area-inset-bottom));justify-content:space-between;align-items:center;box-shadow:0 -4px 15px #f4f2eb99}.reading .reading-dock{display:flex}.reading-dock button{font-size:14px;min-height:44px;padding:8px 0}.reading-dock>span{font:12px Georgia,serif;color:var(--jade)}.progress{position:absolute;top:0;left:0;right:0;height:2px;background:#c8cec5}.progress span{display:block;background:var(--jade);height:100%;width:0}.desktop-rail{display:none}
dialog{border:0;background:var(--paper);color:var(--ink);padding:0 24px 30px;margin:auto auto 0;width:100%;max-width:600px;max-height:88svh;border-radius:18px 18px 0 0;overscroll-behavior:contain;box-shadow:0 -15px 80px #0002}dialog[open]{animation:sheet-in .22s ease-out}dialog::backdrop{background:#071119aa}body.sheet-open{overflow:hidden}.sheet-top{position:sticky;top:0;background:var(--paper);display:flex;justify-content:flex-end;min-height:57px;padding-top:10px;z-index:1}.sheet-top .handle{height:4px;width:38px;border-radius:4px;background:#aaa;position:absolute;left:calc(50% - 19px);top:10px}.sheet-top button{font-size:14px;min-height:44px;padding:10px 0 4px 15px}#sheet-title{font-family:var(--serif);font-size:34px;margin:12px 0 0;line-height:1.5;letter-spacing:0}.term-english{font:21px/1.5 Georgia,serif;border-bottom:1px solid var(--line);padding-bottom:16px;margin-bottom:22px;overflow-wrap:anywhere}#sheet-body>p{font-size:17px;line-height:1.8}#sheet-body h3{font:13px var(--sans);color:var(--jade);margin:22px 0 8px}#sheet-body .source-link{font-size:14px;display:block;margin-top:24px;border-top:1px solid var(--line);padding:20px 0 5px}#sheet-body .sheet-list{list-style:none;padding:0;margin:18px 0}#sheet-body .sheet-list li{border-bottom:1px solid var(--line)}.sheet-list a,.sheet-list button{display:block;width:100%;text-align:left;padding:15px 0;font-size:17px;text-decoration:none}.sheet-list small{display:block;font-size:12px}.sheet-list button:hover,.sheet-list a:hover{color:var(--jade)}.term-search{display:block;width:100%;font-size:16px;background:transparent;border:1px solid #9eada2;padding:13px;margin-top:20px}.sheet-back{min-height:44px;font-size:13px;text-decoration:underline;margin:18px 0 0;padding:8px 0}.no-script{padding:20px}
@keyframes arrive{from{transform:translateY(12px)}to{transform:none}}@keyframes sheet-in{from{transform:translateY(20px)}to{transform:none}}
@media(min-width:900px){.masthead{padding:0 48px}.masthead:after{left:48px;right:48px}.cover-copy{left:10%;top:22%;width:50%}.cover h1{font-size:80px}.cover-bottom{left:10%;right:10%;bottom:45px}.motion{right:10%;bottom:140px}.reading-shell{display:grid;grid-template-columns:230px minmax(0,690px);gap:55px;max-width:1100px;margin:auto;padding:0 30px}.desktop-rail{display:block;position:sticky;top:110px;align-self:start;margin-top:80px;font-size:13px}.desktop-rail>p{font:24px Georgia,serif}.desktop-rail>span{color:var(--jade)}.desktop-rail nav{display:grid;gap:18px;margin:32px 0}.desktop-rail a{text-decoration:none}.desktop-rail button{padding:12px 0;text-decoration:underline;font-size:13px}article{padding:0 0 90px}article>section{padding-top:75px}.reading-dock{left:auto;width:280px;right:32px;bottom:22px;border:1px solid var(--line);box-shadow:none;padding:4px 20px}.flow-body{gap:50px}.context{width:140px}.context-bracket{left:-30px}.experiment{margin:32px 0;padding:32px}dialog{margin:auto;max-width:520px;border-radius:6px;max-height:85svh}.handle{display:none}.finish h2{font-size:39px}}
@media(max-width:350px){.masthead,.cover-copy{padding-left:20px;padding-right:20px}.cover-copy{left:0;right:0}.cover h1{font-size:39px}article{padding-left:20px;padding-right:20px}.start{font-size:18px;gap:8px}.arrow{width:44px;height:44px}.cover-bottom{left:20px;right:20px;font-size:14px}h2{font-size:32px}.context button{font-size:12px}.flow-body{gap:15px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*:before,*:after{animation:none!important;transition:none!important}}
@media print{.cover,.masthead,.desktop-rail,.reading-dock,dialog,.motion,.form-actions,.solid{display:none!important}.reading-shell{display:block}article{max-width:none;padding:0;font-size:12pt}article>section{break-inside:auto}h2{font-size:24pt}a{color:inherit}.term{text-decoration:none}.feedback[hidden]{display:block}textarea{min-height:80px}}

.chapter-nav{display:flex;flex-wrap:wrap;gap:20px;justify-content:space-between;border-top:1px solid var(--line);padding:25px 0;margin-top:30px;font-size:15px}.chapter-nav>a{min-height:44px;display:flex;align-items:center}.chapter-nav>span{font-size:13px;color:var(--jade)}.sheet-list a[aria-current=page]{color:var(--jade);font-weight:600}.downloads{display:grid;gap:12px;margin:24px 0}.downloads a{font-size:15px;padding:8px 0}.experiment select,#rubric-fields select{display:block;width:100%;padding:12px 10px;background:var(--paper);border:1px solid #9eada2;color:var(--ink);font:15px var(--sans);min-height:44px;margin:12px 0}.sequence-strip{display:grid;grid-template-columns:1fr 22px 1fr;align-items:center;gap:10px;margin:30px 0}.sequence-strip>span{border:1px solid var(--jade);padding:12px;text-align:center;font-size:16px}.sequence-strip small{display:block;font-size:11px}.sequence-strip>b{font-weight:400;text-align:center}.sequence-strip>b:nth-of-type(2){grid-column:1/-1;transform:rotate(90deg)}.process-line{padding:25px 18px;margin:30px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line);display:grid;text-align:center;justify-items:center;gap:8px;font-size:16px}.process-line span{display:block}.process-line small{display:block;font-size:12px}.process-line b{font-weight:400;color:var(--jade)}.metric-list{margin:25px 0}.metric-list p{display:flex;justify-content:space-between;gap:15px;border-bottom:1px solid var(--line);padding:14px 0;margin:0;font-size:15px}.metric-list strong{font-weight:500}.metric-list span{font-size:13px}.chart svg{display:block;width:100%;height:auto;overflow:visible;margin-top:20px}.chart-legend{font-size:11px;display:flex;gap:20px;flex-wrap:wrap;margin:8px 0 20px}.chart-legend span{border-left:12px solid;padding-left:6px;line-height:1.2}.table-wrap{overflow-x:auto;margin:22px 0;-webkit-overflow-scrolling:touch}.table-wrap table{width:100%;border-collapse:collapse;font-size:12px;font-variant-numeric:tabular-nums}.table-wrap th,.table-wrap td{text-align:left;white-space:nowrap;padding:11px 7px;border-bottom:1px solid var(--line)}.table-wrap th{font-weight:500;color:var(--jade)}.experiment [role=status]{font-size:15px;line-height:1.8;margin:22px 0}.flux-bar{margin:16px 0;position:relative;padding-bottom:12px;font-size:13px}.flux-bar i{display:block;height:4px;background:var(--jade);margin-top:8px}.flux-bar:nth-child(2) i{background:#99532b}.flux-bar:nth-child(3) i{background:#8a978d}#rubric-fields label{font-size:14px;margin-top:22px}.desktop-rail a{line-height:1.7}select:focus-visible{outline:2px solid var(--copper);outline-offset:3px}