:root{--paper:#f8f7f0;--ink:#283529;--muted:#636d5e;--gold:#8c753e;--sage:#e3e5d7;--line:#d7d8c9;--serif:Georgia,'Songti SC','STSong',serif;--sans:-apple-system,BlinkMacSystemFont,'Segoe UI','PingFang SC','Microsoft YaHei',sans-serif}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:24px}body{margin:0;background:var(--paper);color:var(--ink);font:16px/1.7 var(--sans);-webkit-font-smoothing:antialiased}h1,h2,h3,p,figure{margin:0}a{color:inherit;text-decoration:none}button,input{font:inherit;color:inherit}button{cursor:pointer}a,button,input{touch-action:manipulation}a:focus-visible,button:focus-visible,input:focus-visible,summary:focus-visible{outline:2px solid var(--gold);outline-offset:5px}.wrap{width:min(1120px,calc(100% - 80px));margin-inline:auto}.skip{position:absolute;top:-100px;left:16px;padding:12px;background:var(--ink);color:white;z-index:5}.skip:focus{top:12px}.header{display:flex;justify-content:space-between;align-items:center;padding:28px 0}.brand{font:32px/1 var(--serif);display:flex;align-items:center;gap:9px;letter-spacing:-1px}.header-actions{display:flex;align-items:center;gap:30px;font-size:13px}.languages{display:flex;align-items:center;gap:11px}.languages span{color:#8b9281}.languages button{padding:10px 2px;border:0;background:none;color:var(--muted);min-height:44px}.languages button[aria-pressed=true]{color:var(--ink);text-decoration:underline;text-underline-offset:6px}.print{border:0;border-bottom:1px solid var(--line);background:none;padding:10px 0}.intro{display:grid;grid-template-columns:1.1fr 1fr;align-items:center;gap:32px;padding:38px 0 30px}.eyebrow{font-size:11px;text-transform:uppercase;letter-spacing:.15em;color:var(--gold);line-height:1.6}h1{font:clamp(42px,5.1vw,67px)/1.09 var(--serif);letter-spacing:-.045em;font-weight:400;margin:24px 0}h2{font:clamp(35px,4vw,48px)/1.13 var(--serif);font-weight:400;letter-spacing:-.035em}h3{font:30px/1.2 var(--serif);font-weight:400;letter-spacing:-.025em}.lead{font-size:18px;max-width:420px;color:var(--muted);line-height:1.75}.button{display:inline-flex;align-items:center;justify-content:space-between;gap:36px;padding:14px 23px;min-height:50px;border:1px solid var(--ink);background:var(--ink);color:var(--paper);border-radius:3px;font-size:14px}.button:hover{background:#44563d}.intro .button{margin:28px 0 18px}.signature{font-size:13px;color:var(--muted)}.intro-art img{display:block;width:100%;height:auto;mix-blend-mode:multiply;aspect-ratio:1;object-fit:contain}.intro-art figcaption{font-size:12px;color:var(--muted);text-align:center;padding-top:7px}.before{padding:20px 25px;border-top:1px solid var(--line);border-bottom:1px solid var(--line);display:flex;gap:20px;align-items:center;margin:12px 0 28px;background:#edeedf}.before p{font-size:14px;line-height:1.7;color:#4c5848}.before strong{color:var(--ink);margin-right:10px}.small-sun{font-size:32px;color:var(--gold)}.guide-nav{display:flex;gap:35px;margin-bottom:12px;font-size:13px}.guide-nav a{display:flex;gap:11px;padding:12px 0}.guide-nav a>span:first-child{color:var(--gold)}.guide-nav a:hover{color:var(--gold)}.section{padding:68px 0;border-bottom:1px solid var(--line)}.wave{display:grid;grid-template-columns:1fr 1fr;gap:54px;align-items:center}.wave-art{align-self:stretch;display:flex;flex-direction:column;justify-content:center;background:#efeede;border-radius:150px 150px 4px 4px;overflow:hidden}.wave-art img{display:block;width:100%;aspect-ratio:1;object-fit:cover;mix-blend-mode:multiply}.wave-art figcaption{font-size:13px;color:var(--muted);padding:0 25px 24px;text-align:center}.wave h2{margin:18px 0}.section-intro{color:var(--muted)}.steps{list-style:none;counter-reset:step;padding:0;margin:27px 0}.steps li{position:relative;padding-left:34px;counter-increment:step;font-size:15px;line-height:1.75;margin:19px 0;color:var(--muted)}.steps li:before{content:counter(step,decimal-leading-zero);position:absolute;left:0;top:2px;font-size:11px;color:var(--gold)}.steps strong{color:var(--ink);font-weight:600}.annotation{font-size:13px;color:var(--muted);padding-left:16px;border-left:2px solid #b4bd9e;line-height:1.75}.section-heading{display:grid;grid-template-columns:1fr 1fr;gap:54px;align-items:end;margin-bottom:36px}.section-heading h2{margin-top:17px}.section-heading>p{color:var(--muted)}.circle-grid{display:grid;grid-template-columns:1fr 1fr;gap:22px}.circle-panel{padding:28px 30px 30px;border-radius:5px;background:#eeeede}.vertical{background:#e5e9dd}.panel-label{display:flex;gap:12px;align-items:center;font-size:12px;color:var(--muted)}.panel-label>span{border:1px solid #aeb69e;border-radius:50%;height:28px;width:28px;display:grid;place-content:center;color:var(--ink);flex-shrink:0}.motion-diagram{width:100%;height:auto;display:block;margin:10px 0}.circle-panel h3{margin:12px 0 15px}.circle-panel>p{font-size:15px;line-height:1.85;color:#4f5e47}.circle-panel p.cue{font-size:12px;color:var(--gold);margin-top:22px;padding-top:16px;border-top:1px solid #cbd0bd}.diagram-note{font-size:12px;color:var(--muted);text-align:center;margin:17px 0 32px}.chair-note{display:grid;grid-template-columns:1fr 3fr;gap:24px;padding:24px 0 0;border-top:1px solid var(--line)}.chair-note>p:last-child{font-size:15px;color:var(--muted)}.notice{display:grid;grid-template-columns:1fr 1fr;gap:54px}.notice h2{margin:17px 0 24px}.notice-copy>p:not(.eyebrow){max-width:405px;color:var(--muted)}.notice-copy .signature{margin-top:22px}.reflection{padding-top:3px}fieldset{border:0;padding:0;margin:0}legend{font-size:13px;color:var(--muted);margin-bottom:14px}fieldset label{display:flex;gap:14px;align-items:center;border-bottom:1px solid #cbd1be;min-height:63px;cursor:pointer;padding:12px 15px}fieldset label:first-of-type{border-top:1px solid #cbd1be}fieldset label:hover,fieldset label:has(input:checked){background:#e8ebdf}fieldset label>span:last-child{margin-left:auto;color:var(--gold)}input[type=radio]{accent-color:var(--ink);width:18px;height:18px;margin:0}.response{font-size:14px;line-height:1.8;color:var(--muted);padding:20px 0 18px;min-height:86px}.reply-actions{display:flex;align-items:center;gap:20px}.reply-actions[hidden]{display:none}.reply-actions button{background:none;border:0;border-bottom:1px solid var(--line);font-size:13px;padding:10px 0}.email-note,.copy-status{font-size:12px;color:var(--muted);margin-top:12px}.copy-status:empty{display:none}.safety{padding:35px 0 40px;max-width:850px}.safety h2{font:24px/1.3 var(--serif);margin-bottom:15px;letter-spacing:0}.safety p{font-size:14px;color:var(--muted)}details{font-size:13px;margin-top:16px;color:var(--muted)}summary{cursor:pointer;padding:4px 0;color:var(--ink)}details p{padding:9px 0}.sources{display:flex;flex-wrap:wrap;gap:17px;font-size:12px;margin-top:16px;color:var(--muted)}.sources a{text-decoration:underline;text-underline-offset:3px}.footer{padding:29px 0 40px;display:flex;align-items:center;justify-content:space-between;border-top:1px solid var(--line);gap:20px}.footer p,.footer>a:last-child{font-size:12px;color:var(--muted)}html[lang=zh-Hans] h1{font-size:clamp(40px,4.6vw,60px);line-height:1.3;letter-spacing:0}html[lang=zh-Hans] h2{line-height:1.35;letter-spacing:0}html[lang=zh-Hans] .lead{line-height:1.9}@media(max-width:760px){.wrap{width:calc(100% - 40px)}.header{padding:21px 0}.brand{font-size:28px}.header-actions{gap:17px}.print{font-size:11px}.intro{gap:5px;padding:25px 0 27px;grid-template-columns:1fr}.intro-copy{max-width:540px}.intro h1{font-size:clamp(42px,9vw,60px)}.lead{font-size:17px}.intro-art{max-width:410px;width:100%;margin:5px auto 0}.intro-art img{max-height:345px}.before{padding:18px 15px;gap:13px}.small-sun{font-size:24px}.before p{font-size:13px}.guide-nav{gap:18px;justify-content:space-between;font-size:11px}.guide-nav a{gap:6px}.section{padding:45px 0}.wave{grid-template-columns:1fr;gap:27px}.wave-art{max-width:470px;width:100%;margin:auto;order:2;border-radius:100px 100px 4px 4px}.wave-art img{max-height:390px}.wave-art figcaption{font-size:12px}.section-heading{grid-template-columns:1fr;gap:22px}.circle-grid{grid-template-columns:1fr;gap:18px}.circle-panel{padding:22px 25px}.motion-diagram{max-height:235px}.chair-note{grid-template-columns:1fr;gap:10px}.notice{grid-template-columns:1fr;gap:30px}.notice-copy>p:not(.eyebrow){max-width:none}.notice h2 br{display:none}.notice h2 br:after{content:' '}.footer{flex-wrap:wrap;gap:17px}.footer .brand{width:100%}.footer p{font-size:11px}h2{font-size:36px}.diagram-note{font-size:12px}.eyebrow{font-size:10px}}@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}@media print{@page{size:A4;margin:14mm}body{font-size:11px;background:white}.wrap{width:100%}.header-actions,.guide-nav,.button,.reflection,.skip,.footer,details{display:none}.header{padding:0 0 10px}.intro{padding:10px 0;grid-template-columns:1.2fr 1fr}.intro h1{font-size:35px}.lead{font-size:13px}.intro-art img{max-height:210px}.intro-art figcaption,.signature{font-size:10px}.before{padding:10px;margin:12px 0}.before p{font-size:10px}.section{padding:25px 0;break-inside:avoid}h2{font-size:28px}.wave{grid-template-columns:.8fr 1.2fr;gap:25px}.wave-art img{max-height:270px}.wave-art figcaption,.steps li,.section-intro,.annotation{font-size:11px}.steps{margin:10px 0}.steps li{margin:10px 0}.section-heading{gap:25px;margin-bottom:15px}.section-heading>p,.circle-panel>p,.chair-note>p:last-child{font-size:11px}.circle-panel{padding:16px}.circle-panel h3{font-size:22px}.motion-diagram{max-height:150px}.notice{grid-template-columns:1fr;padding:20px 0}.notice h2 br{display:none}.notice-copy>p:not(.eyebrow){max-width:none;font-size:11px}.notice-copy .signature{display:none}.safety{padding:20px 0}.safety p{font-size:10px}.sources{font-size:10px}}

/* Match the illustration frames, independently of the copy height. */
@media(min-width:761px){.intro{grid-template-columns:1fr 1fr;gap:54px}.intro-art,.wave-art{align-self:center}.intro-art img,.wave-art img{aspect-ratio:1;object-fit:contain;height:auto}.wave-art{border-radius:8px;background:#f0efe4}.wave-art figcaption{padding-top:10px}}
.spine-basics{padding:42px 0 38px;scroll-margin-top:24px}.spine-basics h2{margin:15px 0 32px}.basics-grid{display:grid;grid-template-columns:1fr 1fr 1fr;gap:36px}.basics-grid h3{font-size:25px;margin:8px 0 12px}.basics-grid p{font-size:15px;color:var(--muted);line-height:1.85}.basic-icon{display:block;font:32px/1.5 var(--serif);color:var(--gold)}.basics-note{font-size:13px;color:var(--muted);margin:28px 0 0;border-top:1px solid var(--line);padding-top:17px}.body-wave{display:block;width:100%;height:auto;aspect-ratio:1}.animation-toolbar{display:flex;align-items:center;justify-content:space-between;gap:14px;font-size:12px;color:var(--muted);padding:8px 24px 0}.animation-toolbar button{font-size:12px;background:transparent;border:1px solid #bbc3ac;border-radius:20px;padding:8px 13px;min-height:44px}.animation-toolbar button:hover{background:#e1e6d6}.wave-art figcaption{font-size:11px;padding:12px 20px 18px}.circles{border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:0;color:var(--ink)}.circles-summary{display:flex;align-items:center;justify-content:space-between;gap:20px;padding:24px 0;font:21px/1.5 var(--serif);list-style:none}.circles-summary::-webkit-details-marker{display:none}.circles[open]>.section-heading{padding-top:20px}.circles[open]>.chair-note{padding-bottom:35px}.guide-nav{padding-top:15px;border-top:1px solid var(--line);margin:18px 0 0}.wave{border-bottom:0}.intro-art figcaption{min-height:28px}.intro-art,.wave-art{border-radius:8px;background:#f0efe4;overflow:hidden}.intro-art figcaption{padding-bottom:13px}.intro-art img{mix-blend-mode:multiply}.before{margin-bottom:0}@media(max-width:760px){.basics-grid{grid-template-columns:1fr;gap:22px}.basics-grid article{position:relative;padding-left:44px}.basic-icon{position:absolute;top:0;left:0;font-size:26px}.basics-grid h3{font-size:25px}.spine-basics{padding:30px 0}.spine-basics h2{font-size:33px;margin-bottom:24px}.circles-summary{font-size:19px}.body-wave{max-height:390px}.intro-art{margin-top:20px}.intro-art figcaption{font-size:11px}.animation-toolbar{padding-inline:20px}.wave-art{border-radius:8px}.guide-nav{gap:12px}}@media print{.basics-grid{grid-template-columns:1fr 1fr 1fr;gap:20px}.spine-basics{padding:20px 0}.spine-basics h2{font-size:27px;margin-bottom:15px}.basics-grid h3{font-size:18px}.basics-grid p{font-size:10px}.basics-note{font-size:10px}.basic-icon{font-size:22px}.body-wave{max-height:270px}.animation-toolbar,.circles{display:none}}
/* Keep both illustration panels on the same visual baseline. */
.intro-art figcaption,.animation-toolbar{min-height:52px}.intro-art figcaption{display:grid;align-content:center;padding:8px 14px}.animation-toolbar{padding:4px 20px}.wave-art figcaption{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%);padding:0;white-space:nowrap}@media print{.intro-art figcaption{min-height:0}}