/* ===== 01 变量 · 复位 · 中文排版 ===== */
:root{
  --abyss:#050A18;
  --panel:#0B1630;
  --violet:#1A1136;
  --violet-lift:#2B1E55;
  --neon:#3EE8D6;
  --amber:#F6B84A;
  --frost:#EEF3FF;
  --steel:#98A6C6;
  --line:#35456E;
  --fresh:#62F0B6;
  --font-head:"PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,-apple-system,"Segoe UI",sans-serif;
  --font-body:var(--font-head);
  --font-mono:ui-monospace,SFMono-Regular,"SF Mono",Menlo,Consolas,"Liberation Mono","Courier New",monospace;
  --topbar-h:64px;
  --rail-w:118px;
  --radius:4px;
  --ease:.24s cubic-bezier(.4,0,.2,1);
  --shadow-panel:0 1px 0 rgba(53,69,110,.7),0 20px 40px -26px rgba(0,0,0,.95);
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
body{
  margin:0;
  padding-top:var(--topbar-h);
  min-height:100vh;
  background:var(--abyss);
  color:var(--frost);
  font-family:var(--font-body);
  font-size:17px;
  line-height:1.78;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
body::before{
  content:"";position:fixed;inset:0;z-index:-2;pointer-events:none;
  background:
    radial-gradient(120% 60% at 80% -12%,rgba(62,232,214,.10),transparent 62%),
    radial-gradient(90% 55% at 8% 4%,rgba(43,30,85,.60),transparent 64%),
    linear-gradient(180deg,#050A18 0%,#070E22 46%,#050A18 100%);
}
body::after{
  content:"";position:fixed;inset:0;z-index:-1;pointer-events:none;
  background:radial-gradient(70% 40% at 52% 110%,rgba(246,184,74,.10),transparent 66%);
}
img,svg,video{max-width:100%;height:auto;display:block}
h1,h2,h3,h4,h5{margin:0 0 12px;font-family:var(--font-head);font-weight:800;line-height:1.22;letter-spacing:-.02em;color:var(--frost)}
p{margin:0 0 16px}
a{color:var(--neon);text-decoration:none;transition:color var(--ease),border-color var(--ease)}
a:hover{color:var(--amber)}
ul,ol{margin:0;padding:0;list-style:none}
button{font:inherit;color:inherit}
.mono{font-family:var(--font-mono);font-variant-numeric:tabular-nums;letter-spacing:.01em}
.sr-only{position:absolute;width:1px;height:1px;margin:-1px;padding:0;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;border:0}
:focus-visible{outline:2px solid var(--neon);outline-offset:2px;border-radius:2px}
#main-content:focus{outline:none}

/* ===== 02 跳转链接 ===== */
.skip-link{
  position:fixed;top:10px;left:10px;z-index:200;
  padding:10px 18px;border-radius:var(--radius);
  background:var(--neon);color:#04121A;font-weight:700;font-size:14px;
  transform:translateY(-180%);transition:transform var(--ease);
}
.skip-link:focus,.skip-link:focus-visible{transform:none;color:#04121A}

/* ===== 03 顶栏框架 ===== */
.site-header{position:relative;z-index:60}
.frame-top{
  position:fixed;top:0;left:0;right:0;height:var(--topbar-h);z-index:70;
  background:rgba(5,10,24,.9);
  border-bottom:1px solid var(--line);
  box-shadow:0 22px 46px -34px rgba(62,232,214,.55);
  -webkit-backdrop-filter:blur(10px);
  backdrop-filter:blur(10px);
}
.frame-top__inner{
  height:100%;display:flex;align-items:center;gap:14px;
  padding:0 clamp(14px,3vw,30px);
}
.brand{display:flex;align-items:center;gap:12px;flex:0 0 auto;color:var(--frost)}
.brand:hover{color:var(--frost)}
.brand__mark{
  display:grid;place-items:center;width:40px;height:40px;
  border:1px solid var(--line);
  border-radius:var(--radius);
  background:linear-gradient(150deg,rgba(62,232,214,.18),rgba(26,17,54,.9));
  color:var(--neon);font-family:var(--font-mono);font-size:13px;letter-spacing:.06em;
  clip-path:polygon(0 0,100% 0,100% 70%,70% 100%,0 100%);
}
.brand__text{display:block;min-width:0}
.brand__line{display:block;font-size:15px;font-weight:800;letter-spacing:-.01em;white-space:nowrap}
.brand__desc{display:block;font-family:var(--font-mono);font-size:11.5px;letter-spacing:.14em;color:var(--steel)}
.frame-hint{
  display:none;margin:0 0 0 auto;padding-left:16px;
  border-left:1px solid var(--line);
  color:var(--steel);font-size:13px;white-space:nowrap;
}
.frame-contact{display:none;margin-left:auto;align-items:center;gap:10px}
.contact-chip{
  display:inline-flex;align-items:center;gap:8px;
  padding:6px 12px;border:1px solid var(--line);border-radius:999px;
  background:rgba(26,17,54,.72);color:var(--frost);font-size:13px;text-decoration:none;
  transition:border-color var(--ease),box-shadow var(--ease);
}
.contact-chip:hover{border-color:var(--neon);color:var(--frost);box-shadow:0 0 0 2px rgba(62,232,214,.14)}
.contact-chip--static{cursor:default}
.contact-chip__label{color:var(--steel);font-size:12px}
.contact-chip__value{color:var(--frost);font-size:13px}
.nav-toggle{
  display:inline-flex;flex-direction:column;align-items:center;justify-content:center;gap:5px;
  margin-left:auto;width:44px;height:44px;flex:0 0 auto;
  border:1px solid var(--line);border-radius:var(--radius);
  background:rgba(43,30,85,.5);color:var(--frost);cursor:pointer;
  transition:border-color var(--ease),box-shadow var(--ease);
}
.nav-toggle:hover{border-color:var(--amber);box-shadow:0 0 0 2px rgba(246,184,74,.22)}
.nav-toggle__bar{display:block;width:18px;height:2px;background:currentColor;transition:transform var(--ease),opacity var(--ease)}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1){transform:translateY(7px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(2){opacity:0}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(3){transform:translateY(-7px) rotate(-45deg)}
.read-progress{position:absolute;left:0;right:0;bottom:-1px;height:2px;background:rgba(53,69,110,.45);overflow:hidden}
.read-progress__bar{
  display:block;width:100%;height:100%;
  transform:scaleX(0);transform-origin:0 50%;
  background:linear-gradient(90deg,var(--neon),var(--amber));
  transition:transform .12s linear;
}

/* ===== 04 左侧编号竖栏 ===== */
.frame-rail{
  display:none;position:fixed;top:var(--topbar-h);left:0;bottom:0;width:var(--rail-w);z-index:55;
  flex-direction:column;gap:14px;padding:26px 12px 20px;
  border-right:1px solid var(--line);
  background:linear-gradient(180deg,rgba(11,22,48,.94),rgba(5,10,24,.96) 52%,rgba(26,17,54,.92));
  overflow-y:auto;
}
.rail-label{
  margin:0 0 4px;padding-left:12px;
  font-family:var(--font-mono);font-size:11px;letter-spacing:.22em;color:var(--line);
}
.rail-nav{display:grid;gap:6px}
.nav-link{text-decoration:none;transition:color var(--ease),background var(--ease),border-color var(--ease),box-shadow var(--ease)}
.rail-link{
  display:block;padding:9px 10px 9px 12px;
  border-left:2px solid transparent;border-radius:0 var(--radius) var(--radius) 0;
  color:var(--steel);font-size:13.5px;font-weight:600;line-height:1.4;
}
.rail-num{display:block;font-family:var(--font-mono);font-size:11px;letter-spacing:.14em;color:var(--line);transition:color var(--ease)}
.rail-link:hover{color:var(--frost);background:rgba(43,30,85,.6)}
.rail-link:hover .rail-num{color:var(--neon)}
.rail-link[aria-current="page"]{color:var(--frost);background:rgba(62,232,214,.08);border-left-color:var(--neon)}
.rail-link[aria-current="page"] .rail-num{color:var(--neon)}
.rail-note{margin:auto 0 0;padding-left:12px;font-size:11px;letter-spacing:.06em;color:var(--line)}

/* ===== 05 移动抽屉 ===== */
.frame-drawer{
  position:fixed;top:var(--topbar-h);left:0;right:0;z-index:65;
  max-height:calc(100vh - var(--topbar-h));overflow-y:auto;
  padding:16px clamp(16px,4vw,28px) 24px;
  border-bottom:1px solid var(--line);
  background:linear-gradient(180deg,rgba(11,22,48,.99),rgba(5,10,24,.99));
  box-shadow:0 46px 70px -34px rgba(0,0,0,.94);
  opacity:0;visibility:hidden;pointer-events:none;transform:translateY(-12px);
  transition:transform var(--ease),opacity var(--ease),visibility var(--ease);
}
.frame-drawer[data-open]{opacity:1;visibility:visible;pointer-events:auto;transform:none}
.drawer-list{display:grid;gap:8px}
.drawer-link{
  display:flex;align-items:baseline;gap:12px;
  padding:12px 14px;border:1px solid var(--line);border-radius:var(--radius);
  background:rgba(11,22,48,.72);color:var(--frost);font-size:15px;font-weight:600;
}
.drawer-num{font-size:12px;letter-spacing:.12em;color:var(--steel)}
.drawer-link:hover{border-color:var(--neon);color:var(--frost)}
.drawer-link:hover .drawer-num{color:var(--neon)}
.drawer-link[aria-current="page"]{border-color:var(--neon);box-shadow:inset 0 0 0 1px rgba(62,232,214,.35);background:rgba(62,232,214,.08)}
.drawer-contact{display:flex;flex-wrap:wrap;align-items:center;gap:12px;margin-top:18px;padding-top:16px;border-top:1px dashed var(--line)}
.drawer-contact__line{margin:0;font-size:12.5px;color:var(--steel)}

/* ===== 06 页面容器 · 面包屑 · 标题组 ===== */
.container{width:100%;max-width:1180px;margin:0 auto;padding:0 clamp(18px,4vw,56px)}
.container--wide{max-width:1360px}
.page-body{padding:clamp(26px,3.5vw,52px) 0 clamp(56px,7vw,110px)}
.crumbs{display:flex;flex-wrap:wrap;align-items:center;margin:0 0 22px;font-family:var(--font-mono);font-size:12px;letter-spacing:.06em;color:var(--steel)}
.crumbs li{display:inline-flex;align-items:center}
.crumbs li+li::before{content:"/";margin:0 10px;color:var(--line)}
.crumbs a{color:var(--steel);border-bottom:1px solid transparent}
.crumbs a:hover{color:var(--neon);border-bottom-color:var(--neon)}
.crumbs [aria-current="page"]{color:var(--frost)}
.section-head{margin:0 0 clamp(20px,3vw,34px)}
.eyebrow{margin:0 0 10px;font-family:var(--font-mono);font-size:12px;letter-spacing:.22em;text-transform:uppercase;color:var(--steel)}
.section-title{font-size:clamp(24px,3vw,30px)}
.section-title::after{content:"";display:block;width:56px;height:2px;margin-top:12px;background:linear-gradient(90deg,var(--neon),rgba(62,232,214,0))}
.sub-title{font-size:21px;font-weight:700;color:var(--amber);letter-spacing:-.01em;margin-bottom:8px}
.lede{max-width:60ch;margin:0;padding-left:16px;border-left:2px solid rgba(62,232,214,.5);color:var(--steel);font-size:18px;line-height:1.8}

/* ===== 07 面板 · 栅格 ===== */
.panel{
  position:relative;
  padding:clamp(18px,2.4vw,30px);
  border:1px solid var(--line);border-radius:var(--radius);
  background:var(--panel);
  box-shadow:var(--shadow-panel);
}
.panel::after{
  content:"";position:absolute;right:-5px;bottom:-5px;width:58%;height:58%;
  border-right:1px solid rgba(53,69,110,.7);border-bottom:1px solid rgba(53,69,110,.7);
  border-radius:0 0 var(--radius) 0;pointer-events:none;
}
.panel--violet{background:linear-gradient(160deg,var(--violet),var(--panel) 72%)}
.panel--flat{box-shadow:0 1px 0 rgba(53,69,110,.5)}
.panel__cap{display:block;margin-bottom:10px;font-family:var(--font-mono);font-size:12px;letter-spacing:.14em;color:var(--steel)}
.grid{display:grid;gap:clamp(16px,2.2vw,28px)}
.grid--2{grid-template-columns:repeat(auto-fit,minmax(280px,1fr))}
.grid--3{grid-template-columns:repeat(auto-fit,minmax(232px,1fr))}
.grid--4{grid-template-columns:repeat(auto-fit,minmax(190px,1fr))}

/* ===== 08 标签 · 按钮 ===== */
.tag{
  display:inline-flex;align-items:center;gap:6px;
  padding:3px 10px;border:1px solid var(--line);border-radius:999px;
  background:rgba(26,17,54,.72);
  font-family:var(--font-mono);font-size:12px;letter-spacing:.08em;color:var(--steel);
}
.tag--neon{color:var(--neon);border-color:rgba(62,232,214,.5);background:rgba(62,232,214,.08)}
.tag--amber{color:var(--amber);border-color:rgba(246,184,74,.5);background:rgba(246,184,74,.08)}
.tag--new{color:var(--fresh);border-color:rgba(98,240,182,.45);background:rgba(98,240,182,.08)}
.btn{
  display:inline-flex;align-items:center;gap:8px;
  padding:11px 18px;border:1px solid var(--line);border-radius:var(--radius);
  background:rgba(11,22,48,.85);color:var(--frost);
  font-size:15px;font-weight:600;text-decoration:none;cursor:pointer;
  transition:border-color var(--ease),box-shadow var(--ease),background var(--ease),color var(--ease);
}
.btn:hover,.btn:focus-visible{border-color:var(--amber);color:var(--frost);box-shadow:0 0 0 2px rgba(246,184,74,.26)}
.btn--sm{padding:8px 14px;font-size:14px}
.btn--amber{
  background:linear-gradient(180deg,#F6B84A,#DF9A22);
  border-color:var(--amber);color:#1A1136;
}
.btn--amber:hover,.btn--amber:focus-visible{color:#120C24;box-shadow:0 0 0 2px rgba(246,184,74,.4)}
.btn--ghost{background:transparent}

/* ===== 09 步骤条 · 对照表 ===== */
.step-list{display:grid;gap:14px}
.step-list__item{
  display:grid;grid-template-columns:auto 1fr;gap:16px;align-items:start;
  padding:16px 18px;border:1px solid var(--line);border-radius:var(--radius);
  background:linear-gradient(140deg,rgba(11,22,48,.96),rgba(26,17,54,.76));
}
.step-list__num{
  display:inline-grid;place-items:center;min-width:36px;height:36px;padding:0 9px;
  border:1px solid rgba(62,232,214,.45);border-radius:999px;
  background:rgba(62,232,214,.08);color:var(--neon);
  font-family:var(--font-mono);font-size:14px;font-variant-numeric:tabular-nums;
}
.step-list__body h3{font-size:17px;margin-bottom:6px}
.step-list__body p{margin:0;color:var(--steel);font-size:15.5px}
.compare{
  position:relative;overflow-x:auto;
  border:1px solid var(--line);border-radius:var(--radius);
  background:var(--panel);
}
.compare::before{content:"";display:block;height:3px;background:linear-gradient(90deg,var(--neon),var(--amber),rgba(246,184,74,0))}
.compare table{width:100%;min-width:520px;border-collapse:collapse;font-size:15px}
.compare th{
  padding:14px 16px;text-align:left;
  background:var(--violet);border-bottom:1px solid var(--line);
  color:var(--steel);font-family:var(--font-mono);font-size:12.5px;letter-spacing:.1em;font-weight:400;
}
.compare td{padding:16px;border-bottom:1px solid rgba(53,69,110,.5);vertical-align:top;line-height:1.6}
.compare tbody tr{transition:background .12s linear}
.compare tbody tr:hover{background:var(--violet-lift)}
.compare tbody tr:last-child td{border-bottom:0}
.compare .is-new{color:var(--fresh)}
.compare .num{font-family:var(--font-mono);font-variant-numeric:tabular-nums}

/* ===== 10 手风琴 · 章节导航 ===== */
.acc{
  position:relative;margin:0 0 12px;overflow:hidden;
  border:1px solid var(--line);border-radius:var(--radius);
  background:var(--panel);
}
.acc::before{
  content:"";position:absolute;left:0;top:0;bottom:0;width:2px;
  background:linear-gradient(180deg,var(--neon),rgba(62,232,214,0));
  opacity:0;transition:opacity var(--ease);
}
.acc[open]{border-color:rgba(62,232,214,.42)}
.acc[open]::before{opacity:1}
.acc__head{
  display:flex;align-items:center;gap:12px;
  padding:18px 20px;cursor:pointer;list-style:none;
  font-size:17px;font-weight:700;color:var(--frost);
}
.acc__head::-webkit-details-marker{display:none}
.acc__head::after{content:"＋";margin-left:auto;font-family:var(--font-mono);color:var(--steel)}
.acc[open] .acc__head::after{content:"－";color:var(--neon)}
.acc__body{padding:0 20px 20px;color:var(--steel);font-size:16px}
.acc__body p:last-child{margin-bottom:0}
.chapter-nav{display:flex;flex-wrap:wrap;gap:4px 20px;margin:0 0 clamp(20px,3vw,32px);border-bottom:1px solid var(--line)}
.chapter-nav__link{
  display:inline-flex;align-items:center;gap:8px;padding:10px 2px;
  border-bottom:2px solid transparent;
  color:var(--steel);font-size:14px;font-weight:600;
}
.chapter-nav__link::before{content:attr(data-num);font-family:var(--font-mono);font-size:12px;color:var(--line)}
.chapter-nav__link:hover{color:var(--frost)}
.chapter-nav__link:hover::before{color:var(--neon)}
.chapter-nav__link.is-active{color:var(--frost);border-bottom-color:var(--neon)}
.chapter-nav__link.is-active::before{color:var(--neon)}

/* ===== 11 图片容器（页面阶段放素材） ===== */
.img-frame{
  position:relative;display:block;overflow:hidden;
  aspect-ratio:16 / 10;
  border:1px solid var(--line);border-radius:var(--radius);
  background:
    linear-gradient(135deg,rgba(62,232,214,.16),transparent 44%),
    linear-gradient(315deg,rgba(246,184,74,.14),transparent 48%),
    linear-gradient(180deg,var(--panel),var(--violet));
  clip-path:polygon(0 0,100% 0,100% calc(100% - 22px),calc(100% - 22px) 100%,0 100%);
}
.img-frame::after{
  content:"";position:absolute;inset:0;pointer-events:none;
  background:
    repeating-linear-gradient(115deg,rgba(62,232,214,.10) 0 1px,transparent 1px 28px),
    linear-gradient(200deg,transparent 55%,rgba(5,10,24,.55));
}
.img-frame>img,.img-frame>svg{width:100%;height:100%;object-fit:cover}
.img-frame--wide{aspect-ratio:21 / 9}
.img-frame--square{aspect-ratio:1 / 1}
.img-frame__cap{
  position:absolute;left:14px;bottom:14px;z-index:2;
  padding:3px 10px;border:1px solid var(--line);border-radius:999px;
  background:rgba(5,10,24,.72);color:var(--frost);
  font-family:var(--font-mono);font-size:12px;
}
.figure{margin:0}
.figure__cap{margin-top:10px;font-family:var(--font-mono);font-size:12.5px;letter-spacing:.04em;color:var(--steel)}

/* ===== 12 页脚 ===== */
.site-footer{
  position:relative;overflow:hidden;
  margin-top:clamp(40px,6vw,96px);
  padding:clamp(40px,5vw,74px) 0 24px;
  border-top:1px solid var(--line);
  background:
    radial-gradient(64% 60% at 12% 0%,rgba(43,30,85,.9),transparent 62%),
    radial-gradient(58% 80% at 92% 100%,rgba(62,232,214,.10),transparent 66%),
    linear-gradient(180deg,#070E22,#050A18 58%,#0A0F22);
}
.site-footer::before{
  content:"";position:absolute;top:0;left:0;width:min(430px,62%);height:100%;
  background:linear-gradient(160deg,rgba(26,17,54,.85),transparent 72%);
  clip-path:polygon(0 0,100% 0,34% 100%,0 100%);
  pointer-events:none;
}
.footer-glow{
  position:absolute;top:0;left:0;right:0;height:1px;
  background:linear-gradient(90deg,transparent,rgba(62,232,214,.6),rgba(246,184,74,.5),transparent);
}
.footer-inner{position:relative;display:grid;gap:clamp(26px,3.4vw,52px)}
.footer-brand__line{margin:0 0 6px;font-size:19px;font-weight:800;letter-spacing:-.01em}
.footer-brand__desc{margin:0 0 14px;font-size:12.5px;letter-spacing:.1em;color:var(--neon)}
.footer-brand__note{margin:0 0 14px;max-width:42ch;color:var(--steel);font-size:15px}
.footer-brand__sig{
  display:inline-block;margin:0;padding:4px 12px;
  border:1px solid rgba(246,184,74,.45);border-radius:999px;
  color:var(--amber);font-size:13px;letter-spacing:.06em;
}
.footer-cols{display:grid;gap:24px;grid-template-columns:repeat(auto-fit,minmax(150px,1fr))}
.footer-col__title{
  display:flex;align-items:center;gap:8px;
  margin:0 0 14px;font-size:15px;font-weight:700;color:var(--frost);
}
.footer-col__title .mono{color:var(--amber);font-size:12px;letter-spacing:.12em}
.footer-links li+li{margin-top:2px}
.footer-links a{display:inline-flex;align-items:center;padding:6px 0;color:var(--steel);font-size:15px}
.footer-links a::before{
  content:"";display:inline-block;width:8px;height:1px;margin-right:9px;
  background:var(--line);transition:background var(--ease),width var(--ease);
}
.footer-links a:hover{color:var(--frost)}
.footer-links a:hover::before{width:14px;background:var(--neon)}
.footer-contact{padding:18px 20px;border:1px solid var(--line);border-radius:var(--radius);background:rgba(11,22,48,.72)}
.footer-contact__list{display:grid;gap:12px;margin:0 0 16px}
.footer-contact__list li{display:flex;flex-wrap:wrap;align-items:center;gap:10px}
.footer-contact__key{
  min-width:74px;font-family:var(--font-mono);font-size:12px;letter-spacing:.08em;color:var(--steel);
}
.footer-contact__val{color:var(--frost);font-size:14.5px}
.copy-chip{
  display:inline-flex;align-items:center;gap:8px;
  padding:4px 12px;border:1px dashed var(--line);border-radius:999px;
  background:rgba(11,22,48,.7);color:var(--frost);font-size:13px;cursor:pointer;text-align:left;
  transition:border-color var(--ease),background var(--ease),color var(--ease),box-shadow var(--ease);
}
.copy-chip::after{content:"复制";font-size:11px;color:var(--steel);font-family:var(--font-body)}
.copy-chip:hover{border-style:solid;border-color:var(--neon);box-shadow:0 0 0 2px rgba(62,232,214,.14)}
.copy-chip.is-copied{border-style:solid;border-color:var(--neon);background:rgba(62,232,214,.12);color:var(--neon)}
.copy-chip.is-copied::after{content:"已复制";color:var(--neon)}
.footer-base{
  position:relative;display:flex;flex-wrap:wrap;gap:10px 22px;align-items:center;
  margin-top:clamp(30px,4vw,52px);padding-top:18px;
  border-top:1px dashed var(--line);
}
.footer-base p{margin:0;font-size:13px;color:var(--steel)}
.footer-base__icp{color:var(--frost);letter-spacing:.04em}
.footer-base__sig{margin-left:auto;color:var(--amber)}

/* ===== 13 返回顶部 · 显现 ===== */
.to-top{
  position:fixed;right:clamp(14px,3vw,30px);bottom:clamp(14px,3vw,30px);z-index:80;
  display:grid;place-items:center;width:52px;height:52px;
  border:1px solid var(--line);border-radius:50%;
  background:rgba(11,22,48,.92);color:var(--neon);cursor:pointer;
  opacity:0;visibility:hidden;transform:translateY(10px);
  transition:opacity var(--ease),transform var(--ease),visibility var(--ease),border-color var(--ease),box-shadow var(--ease);
}
.to-top.is-visible{opacity:1;visibility:visible;transform:none}
.to-top:hover{border-color:var(--amber);box-shadow:0 0 0 2px rgba(246,184,74,.22)}
.to-top__ring{position:absolute;inset:0;width:100%;height:100%;transform:rotate(-90deg)}
.to-top__track,.to-top__value{fill:none;stroke-width:2}
.to-top__track{stroke:rgba(53,69,110,.85)}
.to-top__value{stroke:var(--amber);stroke-linecap:round;stroke-dasharray:119.4;stroke-dashoffset:119.4;transition:stroke-dashoffset .12s linear}
.to-top__arrow{position:relative;font-size:16px;line-height:1}
html[data-reveal-ready] [data-reveal]{opacity:0;transform:translateY(12px);transition:opacity .5s ease,transform .5s ease}
html[data-reveal-ready] [data-reveal].is-in{opacity:1;transform:none}

/* ===== 14 断点 ===== */
@media (min-width:768px){
  .frame-contact{display:flex}
  .drawer-list{grid-template-columns:1fr 1fr}
  .footer-inner{grid-template-columns:repeat(2,1fr)}
  .footer-brand{grid-column:1 / -1}
}
@media (min-width:1024px){
  body{padding-left:var(--rail-w)}
  .frame-rail{display:flex}
  .frame-drawer{display:none}
  .nav-toggle{display:none}
}
@media (min-width:1100px){
  .footer-inner{grid-template-columns:1.05fr 1.75fr 1.2fr}
  .footer-brand{grid-column:auto}
}
@media (min-width:1180px){
  .frame-hint{display:block}
}
@media (max-width:767px){
  .brand__desc{display:none}
  .footer-base__sig{margin-left:0}
}

/* ===== 15 无障碍偏好 ===== */
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
  }
  html[data-reveal-ready] [data-reveal]{opacity:1;transform:none}
  .read-progress__bar{transition:none}
  .to-top__value{transition:none}
}