:root{--rb-ground:#f7f8fb;--rb-paper:#ffffff;--rb-ink:#172033;--rb-grey:#4b5568;--rb-line:#d9deea;--rb-blue:#1e3a8a;--rb-blue-deep:#172554;--rb-blue-tint:#e8edfa;--rb-red:#c81e1e;--rb-red-deep:#a51818;--rb-red-tint:#fdecec;--rb-stripe:repeating-linear-gradient(135deg, #c81e1e 0 12px, #ffffff 12px 20px, #1e3a8a 20px 32px, #ffffff 32px 40px);--rb-serif:"Songti SC", "Noto Serif SC", "Source Han Serif SC", STSong, Georgia, serif;--rb-sans:"PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Noto Sans CJK SC", "Segoe UI", Arial, sans-serif}body{margin:0;color:var(--rb-ink);background:var(--rb-ground);font-family:var(--rb-sans);font-size:16px;line-height:1.75}a{color:var(--rb-blue)}:focus-visible{outline:3px solid var(--rb-red);outline-offset:2px}.rb-page{box-sizing:border-box;max-width:1180px;margin:0 auto;padding-right:28px;padding-left:28px}.rb-copy{margin:0 0 18px;color:var(--rb-grey)}.rb-copy p{margin:0 0 12px}.rb-fine{margin:14px 0 0;color:var(--rb-grey);font-size:14px}.rb-blank{margin:0;padding:16px 18px;color:var(--rb-grey);border:1px dashed var(--rb-line)}.rb-btn{display:inline-flex;flex:none;align-items:center;justify-content:center;min-height:48px;padding:0 24px;border:1.5px solid transparent;border-radius:4px;font-size:16px;font-weight:700;text-decoration:none;white-space:nowrap}.rb-btn-red{color:#fff;background:var(--rb-red)}.rb-btn-red:hover{background:var(--rb-red-deep)}.rb-btn-blue{color:#fff;background:var(--rb-blue)}.rb-btn-line{color:var(--rb-blue);background:var(--rb-paper);border-color:var(--rb-blue)}.rb-btn-line:hover{background:var(--rb-blue-tint)}.rb-btn-sm{min-height:44px;padding:0 16px;font-size:15px}.rb-btns{display:flex;flex-wrap:wrap;gap:12px;margin:0}.rb-read{display:inline-flex;align-items:center;min-height:44px;margin-top:8px;font-weight:700;text-decoration:none}.rb-read::after{margin-left:6px;color:var(--rb-red);content:"→"}.rb-read:hover{text-decoration:underline}.rb-mast{position:relative;background:var(--rb-paper);border-bottom:3px double var(--rb-ink)}.rb-mast::before{display:block;height:6px;background:var(--rb-stripe);content:""}.rb-mast-row{display:flex;align-items:flex-start;gap:18px;min-height:78px}.rb-title{min-height:44px;display:flex;align-items:center;gap:12px;min-width:0;align-self:center;margin:0 auto 0 0;color:var(--rb-ink);font-family:var(--rb-serif);font-size:24px;font-weight:700;text-decoration:none}.rb-title span{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.rb-title img{flex:none}.rb-stamp{display:grid;flex:none;place-items:center;width:32px;height:32px;color:var(--rb-red);background:var(--rb-paper);border:2px dotted var(--rb-red);font-family:var(--rb-serif);font-size:15px}.rb-bookmarks ul{display:flex;gap:6px;margin:0;padding:0;list-style:none}.rb-ribbon a{display:flex;align-items:center;justify-content:center;min-height:62px;padding:0 14px 12px;color:#fff;font-size:15px;text-decoration:none;white-space:nowrap;clip-path:polygon(0 0, 100% 0, 100% 100%, 50% 82%, 0 100%)}.rb-ribbon-red a{background:var(--rb-red)}.rb-ribbon-blue a{background:var(--rb-blue)}.rb-ribbon a:hover{min-height:70px}.rb-ribbon a[aria-current]{min-height:74px;font-weight:700}.rb-mast-keys{display:flex;flex:none;align-items:center;gap:10px;align-self:center;margin:0}.rb-mast-in{display:inline-flex;align-items:center;min-height:44px;color:var(--rb-ink);text-decoration:none;white-space:nowrap}.rb-slip{position:relative;display:none;align-self:center}.rb-slip > summary{display:flex;align-items:center;min-height:44px;padding:0 14px;border:1.5px solid var(--rb-blue);border-radius:4px;font-weight:700;white-space:nowrap;list-style:none;cursor:pointer}.rb-slip > summary::-webkit-details-marker{display:none}.rb-slip-card{position:absolute;top:calc(100% + 10px);right:0;z-index:30;display:grid;gap:12px;width:min(280px, calc(100vw - 36px));padding:12px;background:var(--rb-paper);border:1px solid var(--rb-line);box-shadow:0 16px 30px rgba(23, 32, 51, .14)}.rb-slip-card ul{display:grid;gap:6px;margin:0;padding:0;list-style:none}.rb-slip-card .rb-ribbon a{justify-content:flex-start;min-height:46px;padding:0 14px;clip-path:polygon(0 0, 100% 0, 94% 50%, 100% 100%, 0 100%)}.rb-stop-press{padding:12px 0;background:var(--rb-red-tint)}.rb-stop-press .rb-page{display:flex;gap:14px}.rb-stop-press b{flex:none;color:var(--rb-red)}.rb-stop-press p{margin:0}.rb-front{padding-top:26px;padding-bottom:30px}.rb-dateline{display:flex;flex-wrap:wrap;justify-content:space-between;gap:4px 20px;margin:0 0 26px;padding:8px 0;color:var(--rb-grey);border-top:1px solid var(--rb-ink);border-bottom:1px solid var(--rb-ink);font-size:14px;letter-spacing:.08em}.rb-lead{display:grid;grid-template-columns:minmax(0, 1.1fr) minmax(0, .9fr);gap:44px}.rb-lead-story h1{margin:0 0 12px;font-family:var(--rb-serif);font-size:36px;line-height:1.25}.rb-deck{margin:0 0 14px;padding-bottom:14px;color:var(--rb-red);border-bottom:1px solid var(--rb-line);font-family:var(--rb-serif);font-size:26px;line-height:1.45}.rb-lead-story .rb-copy{margin-bottom:26px;column-gap:32px;columns:2 220px}.rb-envelope{margin:0 0 6px}.rb-envelope svg{display:block;width:100%;max-width:400px;height:auto;margin:0 auto}.rb-address{padding:18px 22px 16px;background:var(--rb-paper);border:1px solid var(--rb-line);border-left:6px solid transparent;border-image:var(--rb-stripe) 0 0 0 6}.rb-address-to{display:flex;align-items:baseline;gap:14px;margin:0;padding-bottom:8px;border-bottom:1px solid var(--rb-line);font-family:var(--rb-serif);font-size:20px;overflow-wrap:anywhere}.rb-address-to small{flex:none;color:var(--rb-grey);font-family:var(--rb-sans);font-size:14px}.rb-address-ask{margin:12px 0 4px;color:var(--rb-grey);font-size:14px}.rb-wants{display:grid;grid-template-columns:repeat(2, minmax(0, 1fr));gap:0 18px;margin:0;padding:0;list-style:none}.rb-wants a{display:flex;align-items:center;min-height:44px;border-bottom:1px dotted var(--rb-line);font-weight:600;text-decoration:none}.rb-wants a::before{margin-right:8px;color:var(--rb-red);content:"✉"}.rb-figures{display:grid;grid-template-columns:repeat(auto-fit, minmax(220px, 1fr));margin:30px 0 0;border-top:3px double var(--rb-ink)}.rb-figures div{padding:14px 18px 0 0}.rb-figures dt{font-family:var(--rb-serif);font-weight:700}.rb-figures dd{margin:0;color:var(--rb-grey)}.rb-inside{display:grid;grid-template-columns:repeat(3, minmax(0, 1fr));padding-top:30px;padding-bottom:50px}.rb-column{padding:0 26px;border-left:1px solid var(--rb-line);scroll-margin-top:20px}.rb-column:first-child{padding-left:0;border-left:0}.rb-column:last-child{padding-right:0}.rb-col-no{margin:0 0 6px;color:var(--rb-red);font-size:13px;font-weight:700;letter-spacing:.12em}.rb-column h2,.rb-band h2,.rb-shop h2,.rb-postscript h2{margin:0 0 8px;font-family:var(--rb-serif);font-size:28px;line-height:1.3}.rb-uses{margin:0}.rb-uses dt{margin-top:12px;font-family:var(--rb-serif);font-size:18px;font-weight:700}.rb-uses dd{margin:0;color:var(--rb-grey)}.rb-pull{margin:0 0 14px;padding:10px 0;border-top:2px solid var(--rb-ink);border-bottom:1px solid var(--rb-ink);font-family:var(--rb-serif);font-size:20px;line-height:1.5}.rb-letter{padding:12px 0;border-bottom:1px solid var(--rb-line)}.rb-letter h3{margin:0 0 4px;font-family:var(--rb-serif);font-size:17px}.rb-letter p{margin:0;color:var(--rb-grey);font-size:15px}.rb-band{padding:56px 0;background:var(--rb-blue-tint);border-top:3px double var(--rb-ink);scroll-margin-top:20px}.rb-slider{position:relative}.rb-track{display:grid;grid-auto-columns:minmax(280px, 340px);grid-auto-flow:column;gap:18px;margin:0;padding:6px 2px 18px;overflow-x:auto;scroll-snap-type:x mandatory;list-style:none}.rb-env{position:relative;display:flex;flex-direction:column;padding:26px 24px 22px;background:var(--rb-paper);border:8px solid transparent;border-image:var(--rb-stripe) 8;scroll-snap-align:start}.rb-env-pick{box-shadow:0 12px 26px rgba(200, 30, 30, .18)}.rb-env-stamp{position:absolute;top:16px;right:16px;padding:4px 8px;color:var(--rb-red);border:2px dotted var(--rb-red);font-family:var(--rb-serif);font-size:14px;font-weight:700}.rb-env h3{margin:0;padding-right:4em;font-family:var(--rb-serif);font-size:22px}.rb-env-price{margin:8px 0 12px;padding-bottom:12px;color:var(--rb-blue);border-bottom:1px solid var(--rb-line);font-family:var(--rb-serif);font-size:32px;line-height:1.2}.rb-env-price small{color:var(--rb-grey);font-family:var(--rb-sans);font-size:15px}.rb-env-lines{margin:0}.rb-env-lines div{display:flex;align-items:baseline;justify-content:space-between;gap:10px;padding:7px 0;border-bottom:1px dotted var(--rb-line)}.rb-env-lines dd{margin:0;font-weight:700}.rb-env-note{margin:10px 0 16px;color:var(--rb-grey);font-size:14px}.rb-env-note p{margin:0}.rb-env > a{margin-top:auto}.rb-turns{display:flex;gap:10px;margin:6px 0 0}.rb-turn{display:grid;place-items:center;width:46px;height:46px;color:var(--rb-blue);background:var(--rb-paper);border:1.5px solid var(--rb-blue);border-radius:50%;font-size:18px;cursor:pointer}.rb-turn:hover{color:#fff;background:var(--rb-blue)}.rb-shop{padding-top:56px;padding-bottom:40px;scroll-margin-top:20px}.rb-apps{display:grid;grid-template-columns:repeat(auto-fill, minmax(min(250px, 100%), 1fr));gap:14px}.rb-app{display:flex;align-items:center;gap:14px;padding:16px 18px;background:var(--rb-paper);border:1px solid var(--rb-line);border-radius:16px}.rb-app-icon{display:grid;flex:none;place-items:center;width:56px;height:56px;color:#fff;background:linear-gradient(135deg, var(--rb-blue), #3b5bb5);border-radius:14px}.rb-app-icon svg{width:28px;height:28px}.rb-app-meta{flex:1;min-width:0}.rb-app-meta h3{margin:0;font-size:17px}.rb-app-meta p{margin:0;color:var(--rb-grey);font-size:14px}.rb-app-meta em{display:none;color:var(--rb-red);font-size:13px;font-style:normal;font-weight:700}.rb-get{display:inline-flex;flex:none;align-items:center;min-height:44px;padding:0 18px;color:var(--rb-blue);background:var(--rb-blue-tint);border-radius:999px;font-weight:700;text-decoration:none}.rb-get:hover{color:#fff;background:var(--rb-blue)}.rb-app[data-v4-current]{border-color:var(--rb-red)}.rb-app[data-v4-current] em{display:block}.rb-postscript{padding-top:40px;padding-bottom:64px;text-align:center}.rb-postscript p{margin:0 0 22px;color:var(--rb-grey)}.rb-postscript .rb-btns{justify-content:center;margin:0}.rb-head{padding-top:32px;padding-bottom:22px}.rb-trail{display:flex;flex-wrap:wrap;align-items:center;gap:8px;color:var(--rb-grey);font-size:14px}.rb-trail a{display:inline-flex;align-items:center;min-height:44px;color:var(--rb-grey)}.rb-head h1{margin:0 0 6px;font-family:var(--rb-serif);font-size:34px;line-height:1.3}.rb-head p{margin:0;color:var(--rb-grey)}.rb-desk{display:grid;gap:28px;align-items:start}.rb-desk-toc{grid-template-columns:minmax(0, 1fr) 260px}.rb-airmail{min-width:0;padding:34px 38px;background:var(--rb-paper);border:10px solid transparent;border-image:var(--rb-stripe) 10}.rb-letter-body > p{max-width:760px}.rb-para{scroll-margin-top:20px}.rb-para > :is(h2,h3,h4){margin:26px 0 8px;font-family:var(--rb-serif);line-height:1.45}.rb-para:first-of-type > :is(h2,h3){margin-top:0}.rb-para-group > h2{padding-bottom:6px;color:var(--rb-blue);border-bottom:1px solid var(--rb-line);font-size:24px}.rb-para-item > :is(h2,h3){font-size:20px}.rb-para p{max-width:760px;margin:0 0 12px}.rb-after-h{margin:26px 0 6px;font-family:var(--rb-serif);font-size:22px}.rb-after{margin:0;padding-left:22px}.rb-toc{position:sticky;top:20px;padding:18px 20px;background:var(--rb-paper);border:1px solid var(--rb-line)}.rb-toc h2{margin:0 0 8px;color:var(--rb-red);font-family:var(--rb-serif);font-size:17px}.rb-toc ol{margin:0;padding:0;list-style:none}.rb-toc a{display:flex;align-items:center;min-height:44px;color:var(--rb-ink);border-bottom:1px dotted var(--rb-line);font-size:15px;text-decoration:none}.rb-toc a::before{width:10px;height:10px;margin-right:10px;border:2px dotted var(--rb-blue);content:""}.rb-toc-item a{padding-left:12px}.rb-more{display:flex;flex-wrap:wrap;align-items:center;column-gap:26px;padding-top:30px;padding-bottom:64px}.rb-more h2{flex-basis:100%;margin:0;color:var(--rb-grey);font-size:15px}.rb-gate{max-width:680px;padding-top:56px;padding-bottom:80px}.rb-gate-letter h1{margin:0 0 18px;font-family:var(--rb-serif);font-size:30px;line-height:1.3}.rb-gate-letter .rb-dateline{margin-bottom:18px}.rb-gate-letter .rb-address-to{margin-bottom:20px}.rb-gate-bar{--v4-bar-h:8px;--v4-bar-r:0;--v4-bar-track:var(--rb-blue-tint);--v4-bar-fill:var(--rb-red);margin-top:22px}.rb-gate-bar p{margin:8px 0;color:var(--rb-grey)}.rb-gate-letter [role="status"]{margin:0 0 20px}.rb-foot{padding:48px 0 0;color:#c7d2fe;background:var(--rb-blue-deep)}.rb-foot::after{display:block;height:8px;margin-top:30px;background:var(--rb-stripe);content:""}.rb-foot-top{display:flex;flex-wrap:wrap;align-items:center;gap:8px 26px;margin-bottom:26px}.rb-title-foot{color:#fff}.rb-foot-about{margin:0}.rb-foot-h{margin:0 0 6px;color:#fca5a5;font-size:13px;letter-spacing:.14em}.rb-flight{position:relative;display:flex;flex-wrap:wrap;column-gap:34px;margin:0 0 28px;padding:18px 0 0;list-style:none}.rb-flight::before{position:absolute;top:6px;right:0;left:0;border-top:2px dashed rgba(199, 210, 254, .55);content:""}.rb-flight li{position:relative}.rb-flight li::before{position:absolute;top:-17px;left:0;width:10px;height:10px;background:var(--rb-blue-deep);border:2px solid #fca5a5;border-radius:50%;content:""}.rb-stop{display:inline-flex;align-items:center;min-height:44px;color:#fff;text-decoration:none}.rb-stop:hover{text-decoration:underline}.rb-foot-cols{display:grid;grid-template-columns:minmax(0, 2fr) minmax(0, 1fr);gap:32px}.rb-foot-cols p{margin:0}.rb-foot-row{display:flex;flex-wrap:wrap;column-gap:22px}.rb-foot-a{display:inline-flex;align-items:center;min-height:44px;color:#fff;text-decoration:none}.rb-foot-a:hover{text-decoration:underline}.rb-foot-imprint{display:flex;flex-wrap:wrap;justify-content:space-between;gap:6px 24px;margin:24px 0 0;padding-top:16px;border-top:1px solid rgba(199, 210, 254, .2);font-size:14px}@media (max-width: 1100px){.rb-bookmarks,.rb-mast-in{display:none}.rb-mast-row{align-items:center}.rb-slip{display:block}.rb-lead,.rb-desk-toc{grid-template-columns:minmax(0, 1fr)}.rb-toc{position:static;order:-1}.rb-inside{grid-template-columns:minmax(0, 1fr)}.rb-column,.rb-column:first-child,.rb-column:last-child{padding:22px 0;border-top:1px solid var(--rb-line);border-left:0}}@media (max-width: 680px){.rb-page{padding-right:18px;padding-left:18px}.rb-mast-row{gap:10px;min-height:66px}.rb-title{font-size:20px}.rb-btn-sm{padding:0 12px}.rb-lead-story h1,.rb-head h1{font-size:28px}.rb-deck{font-size:21px}.rb-wants{grid-template-columns:minmax(0, 1fr)}.rb-column h2,.rb-band h2,.rb-shop h2,.rb-postscript h2{font-size:25px}.rb-track{grid-auto-columns:minmax(250px, 86%)}.rb-airmail{padding:22px 18px}.rb-foot-cols{grid-template-columns:minmax(0, 1fr)}.rb-flight{display:grid;grid-template-columns:repeat(2, minmax(0, 1fr));column-gap:18px;padding:0}.rb-flight::before{display:none}.rb-flight li{padding-left:20px}.rb-flight li::before{top:17px}}.v4-ribbon{--v4-notice-bg:rgb(253, 236, 236);--v4-notice-ink:rgb(23, 32, 51)}.v4.v4-ribbon .v4-top-announcement-inner{width:100%;max-width:none;padding-left:0;padding-right:0}.v4.v4-ribbon .v4-top-announcement-inner{max-width:1180px;padding-left:28px;padding-right:28px}@media (max-width: 680px){.v4.v4-ribbon .v4-top-announcement-inner{padding-left:18px;padding-right:18px}}