/* A quiet manuscript reading surface within the mountain-and-ink visual world. */
@font-face{font-family:LongCang;src:url(home/LongCang-Regular.ttf) format('truetype');font-display:swap}
:root{--v-bg:#ece5d4;--v-nav-bg:#171c18;--v-tt:#302e26;--v-tt-2:#746b58;--v-tt-3:#8c8069;--v-bd:#c9bda2;--v-ac:#855031;--v-ac-bg:#dfd1b4;--v-hover-bg:#dcd1b9;--v-f-size:18px;--paper:#eee8d9;--paper-panel:#f5efe2;--paper-header:#e3d8c0;--reader-gold:#c7af79;--reader-serif:'STKaiti','KaiTi','Songti SC','SimSun',Georgia,serif;--reader-line:rgba(183,155,98,.24);--reader-muted:#aaa38e}
html{color-scheme:light}body{background:#20251f;color:var(--v-tt);font-family:var(--reader-serif);line-height:1.9}
*{scrollbar-width:thin;scrollbar-color:#9c8965 transparent}a,button{-webkit-tap-highlight-color:transparent}button{font-family:inherit}a:focus-visible,button:focus-visible{outline:2px solid #bd834e;outline-offset:4px}::selection{background:#caba91;color:#232820}
#sidebar{background:linear-gradient(180deg,rgba(19,26,21,.93),#151b17 350px),url(home/limits.png) center top/cover;border-right:1px solid var(--reader-line);width:280px;padding:0 0 26px;color:#ded5bb;box-shadow:8px 0 30px #10161022}
.reader-brand{display:flex;gap:13px;align-items:center;padding:29px 24px 25px;text-decoration:none;color:#e8ddc0;font-size:23px;letter-spacing:3px;line-height:1.4;border-bottom:1px solid var(--reader-line)}.reader-brand small{display:block;font-family:var(--reader-serif);font-size:10px;letter-spacing:2px;color:#b6ad91;margin-top:5px}.reader-seal{background:#743e30;border:1px solid #aa6751;outline:1px solid #6f4433;outline-offset:3px;font-size:28px;color:#e5c5aa;line-height:1;padding:4px;transform:rotate(-3deg)}.reader-nav-label{font-size:12px;letter-spacing:5px;padding:22px 26px 13px;color:#b49c70}
#doc-nav-list>li>a{padding:9px 24px;font-size:15px;color:#c0baa5;line-height:1.6;border-left-width:2px;white-space:normal}#doc-nav-list>li>a:hover{color:#f5e5bc;background:#ac976512}#doc-nav-list>li>a.current{border-color:#bd9b5c;background:linear-gradient(90deg,#bb9c5f25,transparent);color:#eed5a0;font-weight:400}
#doc-nav-list ul.chapter-toc{border-left-color:#7b6e4a66;margin:9px 18px 15px 27px}#doc-nav-list ul.chapter-toc a{color:#aaa58f;font-size:13px;line-height:1.65;padding:5px 8px;font-family:var(--reader-serif);border:0;border-radius:0}#doc-nav-list ul.chapter-toc a:hover,#doc-nav-list ul.chapter-toc a.toc-active{color:#ead5a4;background:#9e875815}#doc-nav-list ul.chapter-toc ul ul a{font-size:12px;color:#9c9784}.reader-science{display:block;margin:24px 24px 0;padding-top:17px;border-top:1px solid var(--reader-line);font-size:12px;color:#b2a489;text-decoration:none}.nav-divider{background:var(--reader-line)}.nav-section-title{color:#c4af80}
#main{margin-left:280px;background:radial-gradient(ellipse at 50% 0,#394032,#20271f 700px);scroll-behavior:smooth;scroll-padding-top:86px;position:relative}
#topbar{height:62px;min-height:62px;flex-shrink:0;background:#19211bf5;border-bottom:1px solid var(--reader-line);color:#e0d6bc;padding:0 30px;backdrop-filter:blur(12px);gap:19px}#topbar-title{font-size:15px;letter-spacing:2px;font-weight:400;color:#cbbd9b}#sidebar-toggle,#pdf-btn,#reading-mode{border:1px solid #98825755;border-radius:0;color:#cdbd99;background:transparent;font:inherit;font-size:12px;padding:5px 12px;cursor:pointer;line-height:1.6}#sidebar-toggle{font-size:18px;padding:3px 10px}#reading-mode:hover,#pdf-btn:hover{background:#b29b6220}#reading-progress{color:#a99e85;font-size:11px;min-width:32px;font-family:Georgia,serif;font-variant-numeric:tabular-nums}.reader-progress-track{height:2px;flex-shrink:0;position:sticky;top:62px;z-index:51;background:transparent}#reading-progress-bar{display:block;width:0;height:100%;background:#c6a367;transition:width .1s}
.reader-banner{position:relative;isolation:isolate;min-height:265px;flex-shrink:0;display:flex;align-items:center;overflow:hidden;border-bottom:1px solid #8b795444;margin-bottom:0;background:#20291f}.reader-banner-art{position:absolute;inset:0;z-index:-2;background-size:cover;background-position:center 43%;opacity:.72}.reader-banner::after{content:'';position:absolute;inset:0;z-index:-1;background:linear-gradient(90deg,#1b241df2 3%,#20281f70 62%,#20271f22),linear-gradient(0deg,#20271f,transparent 60%)}.reader-banner-copy{max-width:920px;width:100%;padding:37px 52px 42px;margin:auto;color:#ebdcba}.reader-banner-copy p{font-size:13px;letter-spacing:6px;color:#c5ac79;line-height:1.6;margin:0 0 12px}.reader-banner-copy h1{font-family:LongCang,var(--reader-serif);font-size:64px;font-weight:400;line-height:1.2;letter-spacing:9px;border:0;margin:0 0 13px;padding:0;color:#ede3cb;text-shadow:0 3px 19px #10190e}.reader-banner-copy>span{font-size:17px;letter-spacing:5px;color:#c6b894}.reader-home{position:absolute;right:30px;top:23px;color:#d3c29d;font-size:11px;letter-spacing:2px;text-decoration:none;border-bottom:1px solid #b99d5b66;padding-bottom:4px}
#content{position:relative;max-width:920px;width:calc(100% - 72px);margin:0 auto;padding:48px 60px 70px;background:var(--paper);background-image:radial-gradient(ellipse at top right,#bba57613,transparent 70%);border:1px solid #b4a27a66;border-top:3px double #a79160;box-shadow:0 14px 55px #080f092d;font-size:18px;line-height:1.95;flex-shrink:0;overflow-wrap:break-word;outline:none}
#content>h1{font-family:var(--reader-serif);font-size:29px;font-weight:400;line-height:1.5;color:var(--v-tt);margin:0 0 37px;padding:0 0 18px;border-bottom:1px solid var(--v-bd);letter-spacing:2px}#content h2{font-family:var(--reader-serif);font-size:25px;font-weight:600;color:var(--v-ac);margin:2.2em 0 1em;padding:0 0 .45em;border-bottom:1px solid var(--v-bd);letter-spacing:1px}#content h3{font-family:var(--reader-serif);font-size:21px;font-weight:600;margin:1.8em 0 .7em;color:var(--v-tt)}#content h4{font-size:19px;margin:1.5em 0 .65em;font-family:var(--reader-serif)}#content :is(h1,h2,h3,h4){scroll-margin-top:88px}#content p{margin:.8em 0}#content ul,#content ol{padding-left:1.7em;margin:.8em 0}#content li{margin:.35em 0}#content a{color:var(--v-ac);text-underline-offset:4px}#content hr{border:0;border-top:1px solid var(--v-bd);margin:2em 0}#content strong{color:var(--v-tt);font-weight:700}#content :is(img,video,iframe){max-width:100%}#content img{height:auto}#content figure{margin:1.5em 0;text-align:center}#content figcaption{font-size:13px;color:var(--v-tt-2);line-height:1.7;margin-top:10px}#content blockquote{border:0;border-left:2px solid #aa8753;margin:1.2em 0;padding:8px 22px;color:var(--v-tt-2);background:#ad906b0b}#content code{font-size:.85em;background:#987d5112;padding:2px 4px;border-radius:2px}#content pre{background:#262e26;color:#e4dec8;padding:20px;overflow:auto;font-size:13px;line-height:1.7}#content pre code{background:none;padding:0;color:inherit}#content table{border-collapse:collapse;display:block;max-width:100%;overflow:auto;font-size:.92em}#content th,#content td{border:1px solid var(--v-bd);padding:9px 13px}#content th{background:var(--paper-header);font-weight:600}#content tr:nth-child(even){background:#ac91630b}
.math.display,.katex-display{max-width:100%;padding:.6em 0}.katex{font-size:1.05em;letter-spacing:normal}.katex-display>.katex{white-space:nowrap}.math.inline{overflow-wrap:normal}.hl,mark{background:#c9a65b40;color:inherit}.key{color:var(--v-ac)}
.callout{--callout-accent:#736b44;border:1px solid var(--v-bd);border-left:3px solid var(--callout-accent);border-radius:0;background:var(--paper-panel);margin:1.6em 0}.callout .callout-header{background:var(--paper-header);color:var(--callout-accent);font-family:var(--reader-serif);font-size:17px;letter-spacing:1px;font-weight:600;padding:11px 19px}.callout .callout-body{padding:10px 22px 20px;font-size:17px;line-height:1.95}.callout .callout-icon::before{display:inline-grid;place-items:center;border:1px solid currentColor;content:'注';font-size:11px;line-height:1;width:21px;height:23px;margin-right:5px;font-weight:400}.callout-tip{--callout-accent:#49674f}.callout-tip .callout-icon::before{content:'省'}.callout-important{--callout-accent:#8a4c37}.callout-important .callout-icon::before{content:'悟'}.callout-warning{--callout-accent:#876525}.callout-warning .callout-icon::before{content:'慎'}.callout-caution{--callout-accent:#924c41}.callout-caution .callout-icon::before{content:'鉴'}.callout-extension{--callout-accent:#566878}.callout-extension .callout-icon::before{content:'远'}.callout-video-btn,.callout-fold-btn{border-radius:0;font-size:13px;padding:4px 10px;letter-spacing:0}.callout-video-btn{flex-shrink:0;margin-left:auto}.callout-fold-body{background:var(--paper);border-left:2px solid #9a814d;color:var(--v-tt);border-radius:0}.callout-fold-btn[aria-expanded=true]{border-width:1px;padding:4px 10px;background:#9e845b18}
.exercise-block{border:1px solid var(--v-bd);border-top:2px solid #8f7850;border-radius:0;background:var(--paper-panel);margin:1.8em 0}.ex-banner{background:var(--paper-header);color:var(--v-ac);font-family:var(--reader-serif);padding:12px 19px;flex-wrap:wrap;letter-spacing:.04em;font-size:17px}.ex-label{font-weight:600}.ex-dot{font-size:0;width:9px;height:9px;border:1px solid #678469;background:#839b71;transform:rotate(45deg);margin-right:8px}.exercise-block[data-difficulty=medium] .ex-dot{background:#b58b45;border-color:#967335}.exercise-block[data-difficulty=hard] .ex-dot{background:#af6654;border-color:#975241}.ex-tags{width:100%;padding-left:20px}.ex-tag{font-size:10px;background:transparent;border:1px solid #a28d6155;color:var(--v-tt-2);border-radius:0;padding:0 5px;font-weight:400}.ex-body{padding:15px 23px 23px}.ex-problem-box{background:transparent;border:0;border-radius:0;padding:0;line-height:1.95;margin-bottom:19px}.ex-problem-box>p:first-child::before{font-family:var(--reader-serif);color:var(--v-ac)}.ex-sol-row{gap:8px}.ex-sol-label{font-family:var(--reader-serif);font-size:13px;color:var(--v-tt-2)}.ex-action-btn{font-family:var(--reader-serif);font-size:14px;border:1px solid #a08a5e;min-height:34px;padding:4px 19px;border-radius:0;letter-spacing:3px;font-weight:400}.ex-hint-btn{background:transparent;color:var(--v-ac)}.ex-ans-btn{background:#49533e;color:#eee2c3;border-color:#49533e}.ex-sol-btns{gap:10px}.ex-frame{max-height:none;border-radius:0;border-color:var(--v-bd);background:var(--paper)}.ex-hint-panel,.ex-ans-panel{background:var(--paper);color:var(--v-tt);border-left:2px solid #9a8050;font-style:normal}.ex-ans-panel>p:first-child::before{font-family:var(--reader-serif);color:var(--v-ac)}.ex-sol-toggle{border-radius:0;font-family:var(--reader-serif);background:#bda57012;color:var(--v-tt-2);font-size:13px}.ex-video-btn{border-radius:0}
.reader-pagination{display:grid;grid-template-columns:1fr 1fr;gap:20px;max-width:920px;width:calc(100% - 72px);margin:25px auto 55px;flex-shrink:0}.reader-pagination a{border-top:1px solid var(--reader-line);padding:18px 2px;text-decoration:none;color:#ddccab;font-family:var(--reader-serif);font-size:18px}.reader-pagination a:last-child{text-align:right}.reader-pagination small{display:block;font-size:11px;letter-spacing:3px;color:#a99b7e;margin-bottom:7px}.reader-pagination a:hover{color:#ffe6a9}#video-panel{border:1px solid #917744;border-radius:0}#video-close-bottom{font-family:var(--reader-serif)}
html[data-reading-mode=night]{color-scheme:dark;--paper:#252c24;--paper-panel:#2b3329;--paper-header:#343d30;--v-tt:#ded8c7;--v-tt-2:#b4ae9c;--v-tt-3:#a69c83;--v-bd:#5f654d;--v-ac:#d6b782;--v-ac-bg:#4a4e35;--v-hover-bg:#424c37}html[data-reading-mode=night] .callout{--callout-accent:#c6bc8b}html[data-reading-mode=night] .callout-important,html[data-reading-mode=night] .callout-caution{--callout-accent:#d0a38b}html[data-reading-mode=night] .callout-tip{--callout-accent:#b4c299}html[data-reading-mode=night] .callout-extension{--callout-accent:#b2c3cc}
@media(max-width:1100px){#content{padding:38px 34px;width:calc(100% - 40px)}.reader-pagination{width:calc(100% - 40px)}.reader-banner-copy{padding-left:40px}.reader-banner-copy h1{font-size:56px}}
@media(max-width:900px){#sidebar{transform:translateX(-280px)}#sidebar.open{transform:translateX(0)}#main{margin-left:0}#sidebar-toggle{display:block}#topbar{padding:0 18px;gap:12px}.reader-banner{min-height:235px}.reader-brand{padding-top:24px}#overlay.visible{background:#0b120dcc;backdrop-filter:blur(3px)}}
@media(max-width:560px){:root{--v-f-size:17px}#topbar{height:56px;min-height:56px;gap:9px;padding:0 12px}#topbar-title{font-size:13px;letter-spacing:1px}#pdf-btn,#reading-mode{font-size:11px;padding:4px 8px}#reading-progress{font-size:10px;min-width:27px}.reader-progress-track{top:56px}#content{width:calc(100% - 22px);padding:27px 18px 40px;font-size:17px;line-height:1.95}#content>h1{font-size:24px;margin-bottom:26px}#content h2{font-size:22px}#content h3{font-size:20px}.reader-banner{min-height:225px}.reader-banner-copy{padding:45px 29px 35px}.reader-banner-copy h1{font-size:52px;letter-spacing:6px}.reader-banner-copy p{font-size:11px;letter-spacing:4px}.reader-banner-copy>span{font-size:14px}.reader-home{top:15px;right:18px;font-size:10px}.callout .callout-header{padding:10px 12px;font-size:16px;flex-wrap:wrap}.callout .callout-body{padding:8px 13px 16px;font-size:16px}.callout-video-btn{font-size:12px}.ex-banner{padding:10px 13px;font-size:16px}.ex-body{padding:12px 14px 18px}.ex-panel{padding:10px 12px}.ex-action-btn{font-size:14px;min-height:38px}.reader-pagination{width:calc(100% - 36px);gap:15px;margin-bottom:30px}.reader-pagination a{font-size:16px}#content blockquote{padding-left:15px;margin-left:0}.katex{font-size:1em}}
@media(prefers-reduced-motion:reduce){#main{scroll-behavior:auto}*{transition:none!important}}
@media print{html,html[data-reading-mode=night]{color-scheme:light;--paper:white;--paper-panel:white;--paper-header:#f2eee6;--v-tt:#111;--v-tt-2:#444;--v-bd:#bbb;--v-ac:#5b3e24}body,#main,#content{background:white!important;color:#111!important}.reader-banner,.reader-pagination,.reader-progress-track{display:none!important}#content{border:0;box-shadow:none;width:100%!important;font-size:12pt}.callout,.exercise-block{box-shadow:none}.ex-frame{max-height:none}.callout .callout-header{color:#222}.callout,.exercise-block{break-inside:auto}#content h1,#content h2,#content h3{break-after:avoid}#content .katex{color:#111}}

/* Chapter names share one brush-script line; reading sequence is inset. */
#content p{text-indent:2em}
#content li p,#content td p,#content th p,#content figcaption p,#content p[align],#content p:has(>img),#content p:has(>.math.display),#content p:has(>.katex-display){text-indent:0}
.reader-banner-copy .reader-chapter-title{font-size:clamp(28px,4.3vw,64px);letter-spacing:.06em;white-space:nowrap}
.callout-practice{--callout-accent:#6b587b}.callout-practice .callout-icon::before{content:'习'}
html[data-reading-mode=night] .callout-practice{--callout-accent:#c4b2d2}
.ex-label::before{content:'习';display:inline-grid;place-items:center;border:1px solid currentColor;width:21px;height:23px;font-size:11px;font-weight:400;margin-right:10px;vertical-align:middle}
.learning-frame{margin:0 0 2em 2em;padding:8px 22px;border:1px solid var(--v-bd);background:var(--paper-panel);box-shadow:inset 3px 0 0 #a28d6155}
.learning-frame>.callout{margin:16px 0}
@media(max-width:560px){.reader-banner-copy .reader-chapter-title{font-size:clamp(23px,6.2vw,34px);letter-spacing:0}.learning-frame{margin-left:12px;padding:4px 10px}}

.reader-epigraph{box-sizing:border-box;flex-shrink:0;width:calc(100% - 80px);max-width:920px;margin:0 auto;padding:30px 34px 27px;text-align:center;color:var(--v-tt);background:var(--paper);border-bottom:1px solid var(--v-bd)}
.reader-epigraph[hidden]{display:none}
.reader-epigraph blockquote{margin:0;border:0;padding:0;font-family:var(--reader-serif);font-size:23px;line-height:1.9;letter-spacing:.12em}
.reader-epigraph figcaption{margin-top:10px;font-family:var(--reader-serif);font-size:13px;letter-spacing:.06em;color:var(--v-tt-2)}
@media(max-width:1100px){.reader-epigraph{width:calc(100% - 40px)}}
@media(max-width:560px){.reader-epigraph{width:calc(100% - 22px);padding:25px 18px}.reader-epigraph blockquote{font-size:20px;letter-spacing:.05em}.reader-epigraph figcaption{font-size:12px}}
@media print{.reader-epigraph{width:100%;padding:16px 0;background:white;color:#222}}

.banner-epigraph{margin:23px 0 0;color:#e0d2b3;text-shadow:0 2px 8px #101712}
.banner-epigraph blockquote{margin:0;padding:0;border:0;font-family:var(--reader-serif);font-size:23px;letter-spacing:.12em;line-height:1.8}
.banner-epigraph figcaption{margin-top:7px;font-size:12px;letter-spacing:.06em;color:#c6b894}
.chapter-prologue{border:1px solid var(--v-bd);background:var(--paper-panel);padding:26px 30px;margin:0 0 2.4em}
#content .chapter-prologue .prologue-title{margin:0 0 22px;padding:0 0 14px;font-size:25px;font-weight:400;letter-spacing:.08em}
.chapter-prologue p:last-child{margin-bottom:0}
@media(max-width:560px){.banner-epigraph{margin-top:18px}.banner-epigraph blockquote{font-size:18px;letter-spacing:.04em}.chapter-prologue{padding:20px 16px}#content .chapter-prologue .prologue-title{font-size:22px}}

#content .encounter-frame>h2{margin:0 0 22px;padding:0 0 14px;font-size:25px;font-weight:400;letter-spacing:.08em}
.polygon-gallery{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px;margin:25px 0 8px;padding:16px;background:#f0e7d3;border:1px solid #9a754244}
.polygon-gallery img{display:block;width:100%;height:auto;margin:0!important}
#content .diagram-caption{text-indent:0;text-align:center;font-size:14px;color:var(--v-tt-2)}
.triangle-figure{margin:25px auto;text-align:center}.triangle-figure img{display:block;width:100%;max-width:400px;background:#f0e7d3;padding:12px;margin:0 auto 10px}.triangle-figure figcaption{font-size:14px;color:var(--v-tt-2)}
.encounter-frame table{width:100%;font-variant-numeric:tabular-nums}.encounter-frame th,.encounter-frame td{padding:8px 15px}
@media(max-width:560px){.polygon-gallery{grid-template-columns:repeat(2,minmax(0,1fr));gap:8px;padding:8px}#content .encounter-frame>h2{font-size:22px}.encounter-frame th,.encounter-frame td{padding:7px 9px}}

body:not(:has(#content>h1)) #doc-nav-list ul.chapter-toc>li>a{display:block!important}

.limit-figure{margin:26px auto;text-align:center}.limit-figure img{display:block;width:100%;height:auto;margin:0 auto 10px;background:#f0e7d3;padding:12px}.limit-figure figcaption{font-size:14px;color:var(--v-tt-2)}.arc-figure{max-width:440px}