/* ============================================================
   爱科工业建站 · icman.com.cn
   全站核心样式 · 铁灰 + 深黑 + 明黄 · 文具复古工业风
   纯手写 CSS3 · 无框架依赖
   ============================================================ */

/* ---------- 设计变量 ---------- */
:root{
  --bg-paper:#F2EFE6;
  --bg-iron:#E8E5DC;
  --bg-steel:#D8D5CD;
  --bg-dark:#1A1A1C;
  --bg-charcoal:#2A2A2C;
  --bg-graphite:#3A3A3D;
  --iron:#4A4A4C;
  --iron-deep:#333336;
  --iron-light:#6E6E71;
  --yellow:#E8C41F;
  --yellow-deep:#C9A510;
  --yellow-soft:#F7E99C;
  --yellow-tint:#FCF6D6;
  --amber:#E8971F;
  --steel-blue:#2E5F8A;
  --rust:#B5412A;
  --ink:#1A1A1C;
  --ink-soft:#5A5A5D;
  --ink-faint:#9A9A9E;
  --line:#C5C2BA;
  --line-soft:#DDDBD3;
  --line-dark:#4A4A4C;
  --paper-line:#E2DFD6;
  --shadow-s:0 4px 18px -8px rgba(26,26,28,.28);
  --shadow-m:0 14px 40px -18px rgba(26,26,28,.38);
  --shadow-l:0 28px 70px -30px rgba(26,26,28,.48);
  --shadow-y:0 18px 50px -16px rgba(232,196,31,.35);
  --radius-s:4px;
  --radius-m:8px;
  --radius-l:14px;
  --ease:cubic-bezier(.22,.61,.36,1);
  --nav-w:88px;
  --nav-w-open:272px;
  --font-sans:"PingFang SC","Hiragino Sans GB","Microsoft YaHei",-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;
  --font-mono:"JetBrains Mono","Menlo","Consolas","SF Mono",monospace;
}

/* ---------- 重置 ---------- */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
  font-family:var(--font-sans);
  background:var(--bg-paper);
  color:var(--ink);
  font-size:16px;
  line-height:1.75;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
  overflow-x:hidden;
  position:relative;
}
body::before{
  content:"";position:fixed;inset:0;pointer-events:none;z-index:0;
  background:
    repeating-linear-gradient(0deg,transparent,transparent 39px,rgba(232,196,31,.03) 39px,rgba(232,196,31,.03) 40px),
    repeating-linear-gradient(90deg,transparent,transparent 79px,rgba(74,74,76,.025) 79px,rgba(74,74,76,.025) 80px);
}
img{max-width:100%;height:auto;display:block}
a{color:inherit;text-decoration:none;transition:color .3s var(--ease)}
ul,ol{list-style:none}
button{font-family:inherit;cursor:pointer;border:none;background:none}
figure{margin:0}
::selection{background:var(--yellow);color:var(--bg-dark)}
::-moz-selection{background:var(--yellow);color:var(--bg-dark)}

::-webkit-scrollbar{width:12px;height:12px}
::-webkit-scrollbar-track{background:var(--bg-iron)}
::-webkit-scrollbar-thumb{
  background:linear-gradient(180deg,var(--iron),var(--iron-deep));
  border-radius:0;border-left:3px solid var(--bg-iron);border-right:3px solid var(--bg-iron);
}
::-webkit-scrollbar-thumb:hover{background:var(--yellow)}

/* ---------- 布局骨架 ---------- */
.layout{min-height:100vh;display:flex;position:relative;z-index:1}
.content-area{
  flex:1;
  margin-left:var(--nav-w);
  min-width:0;
  transition:margin-left .42s var(--ease);
  position:relative;
}

/* ---------- 光线折射装饰层 ---------- */
.refract-layer{
  position:absolute;pointer-events:none;z-index:0;overflow:hidden;
}
.refract-layer::before{
  content:"";position:absolute;inset:-20% -10% auto 30%;height:80%;
  background:linear-gradient(115deg,transparent 40%,rgba(232,196,31,.08) 45%,rgba(232,196,31,.15) 50%,rgba(46,95,138,.06) 55%,transparent 60%);
  transform:skewX(-15deg);
  filter:blur(20px);
  opacity:.6;
}

/* ---------- 左侧垂直导航 ---------- */
.sidenav{
  position:fixed;top:0;left:0;bottom:0;
  width:var(--nav-w);z-index:1200;
  background:linear-gradient(180deg,var(--bg-dark) 0%,var(--bg-charcoal) 100%);
  border-right:3px solid var(--yellow);
  display:flex;flex-direction:column;
  transition:width .42s var(--ease),box-shadow .42s var(--ease);
  overflow:hidden;
}
.sidenav::before{
  content:"";position:absolute;top:0;left:0;right:0;bottom:0;
  background:
    repeating-linear-gradient(0deg,transparent,transparent 34px,rgba(232,196,31,.04) 34px,rgba(232,196,31,.04) 35px);
  pointer-events:none;
}
.sidenav:hover{
  width:var(--nav-w-open);
  box-shadow:12px 0 40px -12px rgba(26,26,28,.45);
}
.sidenav.scrolled{
  background:linear-gradient(180deg,rgba(26,26,28,.96) 0%,rgba(42,42,44,.96) 100%);
  backdrop-filter:blur(12px);
  -webkit-backdrop-filter:blur(12px);
}

.nav-brand{
  height:88px;display:flex;align-items:center;gap:14px;
  padding:0 22px;border-bottom:1px solid rgba(232,196,31,.2);
  flex-shrink:0;white-space:nowrap;overflow:hidden;position:relative;z-index:2;
}
.nav-brand .logo-mark{width:42px;height:42px;flex-shrink:0}
.nav-brand .logo-text{
  font-size:17px;font-weight:800;color:#fff;letter-spacing:1px;
  opacity:0;transform:translateX(-8px);
  transition:opacity .3s var(--ease) .08s,transform .3s var(--ease) .08s;
}
.nav-brand .logo-text em{font-style:normal;color:var(--yellow);font-weight:900}
.sidenav:hover .nav-brand .logo-text{opacity:1;transform:translateX(0)}

.nav-list{flex:1;padding:12px 0;overflow-y:auto;overflow-x:hidden;position:relative;z-index:2}
.nav-list::-webkit-scrollbar{width:4px}
.nav-list::-webkit-scrollbar-thumb{background:rgba(232,196,31,.3);border-radius:4px;border:none}

.nav-item{position:relative}
.nav-link{
  display:flex;align-items:center;gap:16px;
  padding:14px 24px;color:#C5C2BA;font-size:14.5px;font-weight:500;
  white-space:nowrap;position:relative;
  transition:color .3s var(--ease),background .3s var(--ease);
}
.nav-link .nav-ico{width:24px;height:24px;flex-shrink:0;fill:none;stroke:currentColor;stroke-width:1.6}
.nav-link .nav-label{
  opacity:0;transform:translateX(-6px);
  transition:opacity .28s var(--ease) .06s,transform .28s var(--ease) .06s;
  flex:1;letter-spacing:.3px;
}
.sidenav:hover .nav-link .nav-label{opacity:1;transform:translateX(0)}
.nav-link::before{
  content:"";position:absolute;left:0;top:0;bottom:0;width:3px;
  background:var(--yellow);transform:scaleY(0);transform-origin:top;
  transition:transform .3s var(--ease);
}
.nav-link:hover{color:var(--yellow);background:rgba(232,196,31,.08)}
.nav-link:hover::before{transform:scaleY(1)}
.nav-link.active{color:var(--yellow);background:rgba(232,196,31,.12)}
.nav-link.active::before{transform:scaleY(1)}

.nav-link .nav-arrow{
  width:14px;height:14px;flex-shrink:0;
  opacity:0;transform:translateX(4px);
  transition:opacity .28s var(--ease) .06s,transform .35s var(--ease);
  fill:none;stroke:currentColor;stroke-width:1.8;
}
.sidenav:hover .nav-link .nav-arrow{opacity:.5;transform:translateX(0)}
.nav-item.open > .nav-link .nav-arrow{transform:rotate(90deg);opacity:1}

.submenu{
  max-height:0;overflow:hidden;
  transition:max-height .45s var(--ease);
  background:linear-gradient(180deg,rgba(232,196,31,.06) 0%,rgba(232,196,31,.02) 100%);
  border-top:1px solid rgba(232,196,31,.1);
  border-bottom:1px solid rgba(232,196,31,.1);
}
.submenu-inner{padding:4px 0 8px 0}
.submenu a{
  display:flex;align-items:center;gap:10px;
  padding:9px 24px 9px 64px;font-size:13.5px;
  color:#A5A39C;font-weight:400;white-space:nowrap;position:relative;
  transition:color .3s var(--ease),background .3s var(--ease),padding .3s var(--ease);
}
.submenu a::before{
  content:"";width:6px;height:6px;border-radius:0;background:var(--iron-light);opacity:.5;flex-shrink:0;
  transition:background .3s,opacity .3s,transform .3s;
}
.submenu a:hover{color:var(--yellow);background:rgba(232,196,31,.06);padding-left:72px}
.submenu a:hover::before{background:var(--yellow);opacity:1;transform:rotate(45deg)}
.submenu a.active{color:var(--yellow);font-weight:600;background:rgba(232,196,31,.1)}
.submenu a.active::before{background:var(--yellow);opacity:1;transform:rotate(45deg)}

.submenu a .sub-label{
  opacity:0;transform:translateX(-4px);
  transition:opacity .28s var(--ease) .08s,transform .28s var(--ease) .08s;
}
.sidenav:hover .submenu a .sub-label{opacity:1;transform:none}
.sidenav.open .submenu a .sub-label{opacity:1;transform:none}

.nav-foot{
  padding:16px 24px;border-top:1px solid rgba(232,196,31,.2);
  white-space:nowrap;overflow:hidden;flex-shrink:0;position:relative;z-index:2;
}
.nav-foot .nav-cta{
  display:inline-flex;align-items:center;gap:8px;
  font-size:13px;color:var(--yellow);font-weight:600;
}
.nav-foot .nav-cta .nav-ico{width:18px;height:18px;stroke:var(--yellow);fill:none;stroke-width:1.8}
.nav-foot .nav-cta .nav-label{opacity:0;transition:opacity .3s var(--ease) .08s}
.sidenav:hover .nav-foot .nav-cta .nav-label{opacity:1}

/* 移动端触发 */
.nav-toggle{
  display:none;position:fixed;top:14px;right:18px;z-index:1300;
  width:48px;height:48px;border-radius:50%;
  background:var(--bg-dark);color:var(--yellow);
  box-shadow:var(--shadow-m);
  align-items:center;justify-content:center;gap:0;flex-direction:column;
  border:2px solid var(--yellow);
}
.nav-toggle span{display:block;width:20px;height:2px;background:var(--yellow);margin:2px 0;border-radius:2px;transition:.3s}

.nav-overlay{
  display:none;position:fixed;inset:0;z-index:1100;
  background:rgba(26,26,28,.7);opacity:0;transition:opacity .4s var(--ease);
}
.nav-overlay.show{display:block;opacity:1}

/* ---------- 通用容器 ---------- */
.wrap{max-width:1280px;margin:0 auto;padding:0 40px;position:relative}
.wrap-narrow{max-width:920px;margin:0 auto;padding:0 40px;position:relative}
.wrap-wide{max-width:1480px;margin:0 auto;padding:0 40px;position:relative}

/* ---------- 页面通用头部 ---------- */
.page-hero{
  position:relative;padding:120px 0 70px;overflow:hidden;
  background:
    linear-gradient(135deg,var(--bg-dark) 0%,var(--bg-charcoal) 100%);
  color:#fff;
}
.page-hero::before{
  content:"";position:absolute;inset:0;
  background:
    repeating-linear-gradient(45deg,transparent,transparent 14px,rgba(232,196,31,.04) 14px,rgba(232,196,31,.04) 15px);
}
.page-hero::after{
  content:"";position:absolute;left:0;right:0;bottom:0;height:60px;
  background:linear-gradient(180deg,transparent,var(--bg-paper));
}
.page-hero .ph-eyebrow{
  display:inline-flex;align-items:center;gap:10px;
  font-size:12px;letter-spacing:4px;color:var(--yellow);
  text-transform:uppercase;font-weight:700;margin-bottom:18px;
  padding:6px 14px;border:1px solid var(--yellow);
  font-family:var(--font-mono);
}
.page-hero .ph-eyebrow::before{content:"";width:24px;height:1px;background:var(--yellow)}
.page-hero h1{
  font-size:clamp(34px,4.8vw,60px);font-weight:900;line-height:1.12;
  color:#fff;letter-spacing:-.5px;margin-bottom:20px;
  text-shadow:3px 3px 0 rgba(232,196,31,.15);
}
.page-hero h1 em{font-style:normal;color:var(--yellow);position:relative}
.page-hero p{font-size:17px;color:#B5B3AD;max-width:640px;line-height:1.85}
.page-hero .ph-deco{
  position:absolute;right:-80px;top:-60px;width:420px;height:420px;
  border-radius:0;transform:rotate(12deg);
  background:
    linear-gradient(135deg,rgba(232,196,31,.06),transparent 60%),
    repeating-linear-gradient(0deg,transparent,transparent 30px,rgba(232,196,31,.06) 30px,rgba(232,196,31,.06) 31px);
  pointer-events:none;
}

/* 面包屑 */
.breadcrumb{
  display:flex;align-items:center;gap:8px;font-size:13px;color:#A5A39C;
  margin-bottom:28px;position:relative;z-index:2;
}
.breadcrumb a{color:#A5A39C;transition:color .3s}
.breadcrumb a:hover{color:var(--yellow)}
.breadcrumb svg{width:14px;height:14px;stroke:#A5A39C;fill:none;stroke-width:1.8}
.breadcrumb .current{color:var(--yellow);font-weight:600}

/* 章节标题 */
.sec-title{text-align:center;margin-bottom:56px;position:relative}
.sec-title .eyebrow{
  display:inline-block;font-size:12px;letter-spacing:4px;
  color:var(--iron);font-weight:700;text-transform:uppercase;
  margin-bottom:16px;position:relative;padding:0 48px;
  font-family:var(--font-mono);
}
.sec-title .eyebrow::before,.sec-title .eyebrow::after{
  content:"";position:absolute;top:50%;width:34px;height:1px;background:var(--iron);
}
.sec-title .eyebrow::after{background:var(--yellow);height:3px;width:18px}
.sec-title h2{
  font-size:clamp(28px,3.4vw,42px);font-weight:900;color:var(--ink);letter-spacing:-.3px;
  position:relative;
}
.sec-title h2 em{font-style:normal;color:var(--yellow);position:relative;z-index:1}
.sec-title h2 em::after{
  content:"";position:absolute;left:-4px;right:-4px;bottom:2px;height:10px;
  background:var(--yellow-soft);z-index:-1;opacity:.6;
}
.sec-title p{margin-top:14px;color:var(--ink-soft);max-width:720px;margin-left:auto;margin-right:auto;font-size:15px}

/* ---------- 按钮 ---------- */
.btn{
  display:inline-flex;align-items:center;gap:10px;
  padding:14px 30px;border-radius:0;font-size:14px;font-weight:700;
  letter-spacing:.5px;text-transform:uppercase;
  transition:all .35s var(--ease);position:relative;overflow:hidden;
  font-family:var(--font-sans);
  clip-path:polygon(8px 0,100% 0,calc(100% - 8px) 100%,0 100%);
}
.btn svg{width:18px;height:18px}
.btn-primary{
  background:var(--yellow);color:var(--bg-dark);
  box-shadow:4px 4px 0 var(--iron);
}
.btn-primary:hover{
  background:var(--yellow-deep);transform:translate(-2px,-2px);
  box-shadow:6px 6px 0 var(--iron);
}
.btn-ghost{
  background:transparent;color:var(--ink);border:2px solid var(--ink);
  box-shadow:none;
}
.btn-ghost:hover{
  background:var(--ink);color:var(--yellow);transform:translate(-2px,-2px);
  box-shadow:4px 4px 0 var(--yellow);
}
.btn-light{
  background:#fff;color:var(--bg-dark);border:2px solid var(--yellow);
  box-shadow:3px 3px 0 var(--yellow);
}
.btn-light:hover{background:var(--yellow);transform:translate(-2px,-2px)}
.btn-dark{
  background:var(--bg-dark);color:var(--yellow);border:2px solid var(--yellow);
  box-shadow:3px 3px 0 var(--yellow);
}
.btn-dark:hover{background:var(--yellow);color:var(--bg-dark);transform:translate(-2px,-2px)}
.btn-text{
  display:inline-flex;align-items:center;gap:8px;
  color:var(--ink);font-weight:600;font-size:14px;text-transform:uppercase;letter-spacing:1px;
}
.btn-text svg{width:16px;height:16px;transition:transform .3s var(--ease);stroke:var(--yellow);fill:none;stroke-width:2}
.btn-text:hover{color:var(--yellow)}
.btn-text:hover svg{transform:translateX(4px)}

/* ---------- 滚动渐入 ---------- */
.reveal{opacity:0;transform:translateY(36px);transition:opacity .9s var(--ease),transform .9s var(--ease)}
.reveal.in{opacity:1;transform:none}
.reveal.d1{transition-delay:.1s}
.reveal.d2{transition-delay:.2s}
.reveal.d3{transition-delay:.3s}
.reveal.d4{transition-delay:.4s}

/* ---------- 页脚 ---------- */
.footer{
  background:var(--bg-dark);color:#A5A39C;
  padding:72px 0 0;margin-left:var(--nav-w);position:relative;overflow:hidden;
}
.footer::before{
  content:"";position:absolute;top:0;left:0;right:0;height:4px;
  background:linear-gradient(90deg,var(--yellow),var(--amber),var(--yellow));
}
.footer::after{
  content:"";position:absolute;top:40px;right:5%;width:360px;height:360px;
  background:
    repeating-linear-gradient(0deg,transparent,transparent 24px,rgba(232,196,31,.06) 24px,rgba(232,196,31,.06) 25px),
    repeating-linear-gradient(90deg,transparent,transparent 24px,rgba(232,196,31,.06) 24px,rgba(232,196,31,.06) 25px);
  opacity:.4;pointer-events:none;
}
.footer-grid{display:grid;grid-template-columns:1.5fr 1fr 1fr 1.3fr;gap:48px;position:relative;z-index:2}
.footer h4{color:var(--yellow);font-size:15px;font-weight:800;margin-bottom:22px;letter-spacing:2px;text-transform:uppercase;font-family:var(--font-mono)}
.footer p{font-size:14px;line-height:1.85;color:#8A877F}
.footer .f-brand{display:flex;align-items:center;gap:14px;margin-bottom:20px}
.footer .f-brand img{width:48px;height:48px}
.footer .f-brand strong{color:#fff;font-size:19px;font-weight:900;letter-spacing:1px}
.footer .f-brand strong em{font-style:normal;color:var(--yellow)}
.footer ul li{margin-bottom:12px;font-size:14px;position:relative;padding-left:14px}
.footer ul li::before{
  content:"";position:absolute;left:0;top:8px;width:6px;height:6px;transform:rotate(45deg);
  background:var(--iron);transition:background .3s,transform .3s;
}
.footer ul li a{color:#8A877F;transition:color .3s}
.footer ul li a:hover{color:var(--yellow)}
.footer ul li a:hover + ::before,
.footer ul li:hover::before{background:var(--yellow);transform:rotate(45deg) scale(1.3)}
.footer .f-contact li{display:flex;gap:12px;align-items:flex-start;margin-bottom:14px;font-size:14px;padding-left:0}
.footer .f-contact li::before{display:none}
.footer .f-contact svg{width:18px;height:18px;flex-shrink:0;stroke:var(--yellow);fill:none;stroke-width:1.6;margin-top:3px}
.footer .f-news{display:flex;gap:0;margin-top:18px}
.footer .f-news input{
  flex:1;padding:12px 16px;border-radius:0;border:1px solid rgba(232,196,31,.3);
  background:rgba(255,255,255,.05);color:#fff;font-size:14px;outline:none;
  clip-path:polygon(4px 0,100% 0,calc(100% - 4px) 100%,0 100%);
}
.footer .f-news input::placeholder{color:#6E6E71}
.footer .f-news button{
  width:48px;height:48px;flex-shrink:0;
  background:var(--yellow);color:var(--bg-dark);
  display:flex;align-items:center;justify-content:center;
  clip-path:polygon(0 0,100% 0,100% 100%,8px 100%);
  margin-left:-4px;
}
.footer .f-news button svg{width:18px;height:18px;stroke:currentColor;fill:none;stroke-width:2}
.footer-bottom{
  margin-top:56px;border-top:1px solid rgba(232,196,31,.15);
  padding:24px 0;display:flex;justify-content:space-between;align-items:center;
  font-size:13px;color:#6E6E71;flex-wrap:wrap;gap:12px;position:relative;z-index:2;
}
.footer-bottom .f-links{display:flex;gap:24px;flex-wrap:wrap}
.footer-bottom .f-links a:hover{color:var(--yellow)}
.footer .icp{color:#6E6E71}
.footer .icp a{color:#6E6E71}
.footer .icp a:hover{color:var(--yellow)}

/* ---------- 工具类 ---------- */
.text-center{text-align:center}
.mt-0{margin-top:0}
.section{padding:96px 0}
.section-sm{padding:64px 0}
.bg-iron{background:var(--bg-iron)}
.bg-paper{background:var(--bg-paper)}
.bg-steel{background:var(--bg-steel)}
.bg-dark{background:var(--bg-dark);color:#fff}
.bg-yellow-tint{background:var(--yellow-tint)}