/* ==========================================================================
   Janus Filtration — 共享设计系统 / Shared Design System
   风格：暖色工业 · 钢橙系 (Warm Industrial · Steel & Ember)
   零外部依赖：系统字体栈 + 内联 SVG，离线永久可用
   ========================================================================== */

:root{
  /* --- 主色系：钢橙 --- */
  --primary:#C2410C;        /* 主色·焦橙：按钮、标题强调、数据数字 */
  --primary-dk:#9A3412;     /* 主色深阶：hover */
  --accent:#F59E0B;         /* 渐变搭档·琥珀 */
  --tint:#FFF4EC;           /* 极淡橙底：卡片填充、标签底 */
  --tint-2:#FDF0E6;

  /* --- 钢灰系（工业骨架色）--- */
  --steel:#1F2933;          /* 深钢灰：页脚、深色区块底 */
  --steel-2:#33414F;        /* 次级钢灰 */
  --ink:#1A1F24;            /* 主文本 */
  --sub:#5B6773;            /* 次级文本 */
  --mute:#8A95A0;           /* 注释、英文小标签 */
  --line:#E6E2DC;           /* 分隔线（暖调） */
  --line-dk:#3A4652;        /* 深底上的分隔线 */

  /* --- 底色 --- */
  --bg:#FFFFFF;
  --bg-2:#F7F5F2;           /* 交替区块背景（暖调浅灰） */
  --bg-3:#FAFAF8;

  /* --- 尺寸 --- */
  --radius:12px;
  --radius-lg:18px;
  --shadow:0 4px 16px rgba(26,31,36,.07);
  --shadow-md:0 10px 30px rgba(26,31,36,.10);
  --shadow-lg:0 18px 48px rgba(26,31,36,.14);
  --maxw:1180px;
}

/* ---------- Reset ---------- */
*{margin:0;padding:0;box-sizing:border-box;}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%;}
body{
  font-family:"Noto Sans SC","PingFang SC","Microsoft YaHei","Helvetica Neue",
              Inter,"Segoe UI",Roboto,Arial,sans-serif;
  color:var(--ink);background:var(--bg);line-height:1.72;
  font-size:15px;
  -webkit-font-smoothing:antialiased;
  overflow-x:hidden;
}
img,svg{display:block;max-width:100%;}
a{color:inherit;text-decoration:none;}
button{font-family:inherit;}
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 24px;}
h1,h2,h3,h4,p,li,dd,dt,span,b,small{overflow-wrap:break-word;}

/* ---------- 语言切换 / Language switching ---------- */
[data-lang]{display:none;}
html[data-active-lang="zh"] [data-lang="zh"]{display:revert;}
html[data-active-lang="en"] [data-lang="en"]{display:revert;}
/* 块级元素需要恢复块级 */
html[data-active-lang="zh"] p[data-lang="zh"],
html[data-active-lang="zh"] div[data-lang="zh"],
html[data-active-lang="zh"] h2[data-lang="zh"],
html[data-active-lang="en"] p[data-lang="en"],
html[data-active-lang="en"] div[data-lang="en"],
html[data-active-lang="en"] h2[data-lang="en"]{display:block;}
html[data-active-lang="zh"] b[data-lang="zh"],
html[data-active-lang="zh"] span[data-lang="zh"],
html[data-active-lang="en"] b[data-lang="en"],
html[data-active-lang="en"] span[data-lang="en"]{display:inline;}
html[data-active-lang="zh"] li[data-lang="zh"],
html[data-active-lang="en"] li[data-lang="en"]{display:list-item;}

/* ---------- 按钮 ---------- */
.btn{display:inline-flex;align-items:center;gap:9px;padding:14px 30px;border-radius:8px;
  font-size:15px;font-weight:600;transition:all .22s;cursor:pointer;border:1px solid transparent;
  white-space:nowrap;}
.btn-p{background:var(--primary);color:#fff;box-shadow:0 6px 18px rgba(194,65,12,.24);}
.btn-p:hover{background:var(--primary-dk);transform:translateY(-2px);box-shadow:0 10px 24px rgba(194,65,12,.3);}
.btn-s{background:transparent;color:var(--ink);border-color:var(--line);}
.btn-s:hover{border-color:var(--primary);color:var(--primary);transform:translateY(-2px);}
.btn-ghost{background:rgba(255,255,255,.10);color:#fff;border-color:rgba(255,255,255,.34);}
.btn-ghost:hover{background:rgba(255,255,255,.2);border-color:#fff;transform:translateY(-2px);}
.btn .ar{font-size:16px;line-height:1;}

/* ---------- 区块标题 ---------- */
.sec-head{margin-bottom:44px;max-width:760px;}
.sec-head .bar{width:44px;height:4px;border-radius:2px;
  background:linear-gradient(90deg,var(--primary),var(--accent));margin-bottom:18px;}
.sec-head h2{font-size:clamp(25px,3.4vw,35px);font-weight:700;letter-spacing:-.4px;line-height:1.3;}
.sec-head p{color:var(--sub);margin-top:14px;font-size:16px;}
.sec-head.center{margin-left:auto;margin-right:auto;text-align:center;}
.sec-head.center .bar{margin-left:auto;margin-right:auto;}

/* 英文小标签 */
.eyebrow{font-size:12px;font-weight:600;letter-spacing:2.2px;text-transform:uppercase;
  color:var(--primary);margin-bottom:12px;}

section{padding:88px 0;}
.alt{background:var(--bg-2);}

/* ---------- 滚动揭示（含无 JS 兜底）---------- */
.rv{opacity:0;transform:translateY(22px);transition:opacity .55s ease,transform .55s ease;}
.rv.in{opacity:1;transform:none;}
html.no-js .rv{opacity:1;transform:none;}
@media (prefers-reduced-motion:reduce){
  .rv{transition:none;opacity:1;transform:none;}
  html{scroll-behavior:auto;}
}

/* ---------- 表单 ---------- */
.field{margin-bottom:18px;}
.field label{display:block;font-size:14px;font-weight:600;margin-bottom:7px;}
.field input,.field textarea,.field select{
  width:100%;padding:13px 15px;border:1px solid var(--line);border-radius:9px;
  font-size:15px;font-family:inherit;background:#fff;color:var(--ink);transition:border-color .2s;}
.field input:focus,.field textarea:focus,.field select:focus{
  outline:none;border-color:var(--primary);box-shadow:0 0 0 3px rgba(194,65,12,.1);}

/* ---------- 页脚 ---------- */
footer{background:var(--steel);color:#A8B4C0;font-size:13.5px;padding:56px 0 28px;}
.f-grid{display:grid;grid-template-columns:1.5fr 1fr 1fr 1.2fr;gap:36px;padding-bottom:34px;
  border-bottom:1px solid var(--line-dk);}
.f-grid h4{color:#fff;font-size:14px;font-weight:600;margin-bottom:16px;letter-spacing:.4px;}
.f-grid a,.f-grid p{display:block;color:#A8B4C0;font-size:13.5px;line-height:2.1;}
.f-grid a:hover{color:var(--accent);}
.f-brand b{color:#fff;font-size:19px;display:block;margin-bottom:12px;letter-spacing:.3px;}
.f-brand .f-en{color:var(--mute);font-size:11.5px;letter-spacing:2px;text-transform:uppercase;margin-bottom:14px;}
.f-bottom{display:flex;justify-content:space-between;gap:16px;flex-wrap:wrap;
  padding-top:24px;color:var(--mute);font-size:12.5px;}

/* ---------- 响应式 ---------- */
@media (max-width:920px){
  .f-grid{grid-template-columns:1fr 1fr;gap:28px;}
}
@media (max-width:760px){
  body{font-size:14.5px;}
  section{padding:60px 0;}
  .wrap{padding:0 18px;}
  .sec-head{margin-bottom:32px;}
  .f-grid{grid-template-columns:1fr;gap:24px;}
  .f-bottom{flex-direction:column;gap:8px;}
  .btn{padding:13px 24px;font-size:14.5px;}
}