/* ===== RESET ===== */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{min-height:100vh;background:#1A1A1A;color:#F5F5F5;font-family:'Helvetica Neue','微软雅黑',sans-serif;font-weight:300;font-size:16px;line-height:1.6;-webkit-font-smoothing:antialiased}
img{max-width:100%;display:block}
ul,ol{list-style:none}
a{color:inherit;text-decoration:none}
button{font:inherit;cursor:pointer;border:none;background:none}
:focus-visible{outline:2px solid #FF4500;outline-offset:2px}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{animation-duration:0.01ms!important;animation-iteration-count:1!important;transition-duration:0.01ms!important;scroll-behavior:auto}}

/* ===== CSS VARIABLES ===== */
:root{
  --color-primary:#FF4500;
  --color-primary-hover:#E03D00;
  --color-primary-light:#FF6600;
  --color-dark:#1A1A1A;
  --color-dark-soft:rgba(26,26,26,0.92);
  --color-light:#F5F5F5;
  --color-green:#00CC66;
  --color-red:#FF3333;
  --color-gray:#CCCCCC;
  --color-gray-soft:#E0E0E0;
  --font-heading:'Helvetica Neue','黑体',sans-serif;
  --font-body:'Helvetica Neue','微软雅黑',sans-serif;
  --font-data:Arial,Helvetica,sans-serif;
  --container-max:1200px;
  --header-height:68px;
  --radius-sm:6px;
  --radius-md:12px;
  --radius-lg:30px;
  --shadow-md:0 4px 20px rgba(0,0,0,0.4);
  --transition:0.25s ease
}

/* ===== SKIP LINK ===== */
.skip-link{position:fixed;top:-100px;left:16px;z-index:2000;background:#FF4500;color:#fff;padding:10px 20px;border-radius:0 0 8px 8px;font-weight:600;font-size:14px;transition:top 0.3s}
.skip-link:focus{top:0}

/* ===== CONTAINER ===== */
.container{max-width:var(--container-max);margin:0 auto;padding:0 24px}
@media(max-width:768px){.container{padding:0 16px}}

/* ===== BUTTONS ===== */
.btn{display:inline-flex;align-items:center;justify-content:center;padding:10px 28px;border-radius:var(--radius-lg);font-family:var(--font-heading);font-weight:500;font-size:15px;line-height:1.4;transition:background var(--transition),color var(--transition),box-shadow var(--transition);white-space:nowrap}
.btn--primary{background:var(--color-primary);color:#fff}
.btn--primary:hover,.btn--primary:focus-visible{background:var(--color-primary-hover);box-shadow:0 0 20px rgba(255,69,0,0.35)}
.btn--ghost{background:transparent;border:1.5px solid rgba(255,255,255,0.25);color:var(--color-light)}
.btn--ghost:hover,.btn--ghost:focus-visible{border-color:var(--color-primary);color:var(--color-primary)}

/* ===== BREADCRUMB ===== */
.breadcrumb{display:flex;flex-wrap:wrap;gap:8px;font-size:13px;color:var(--color-gray);font-family:var(--font-heading);letter-spacing:0.04em;padding:16px 0}
.breadcrumb a{color:var(--color-gray);transition:color var(--transition)}
.breadcrumb a:hover{color:var(--color-primary)}
.breadcrumb span+span::before{content:"/";margin-right:8px;color:var(--color-gray)}

/* ===== SECTION ===== */
.section{padding:60px 0}
.section__header{display:flex;align-items:baseline;gap:16px;margin-bottom:32px}
.section__index{font-family:var(--font-heading);font-weight:200;font-size:14px;letter-spacing:0.08em;color:var(--color-gray)}
.section__title{font-family:var(--font-heading);font-weight:100;font-size:48px;letter-spacing:-0.02em;line-height:1.1;color:var(--color-primary)}
@media(max-width:768px){.section{padding:40px 0}.section__title{font-size:32px}}

/* ===== GRID ===== */
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:24px}
.grid--2{grid-template-columns:1fr 1fr}
.grid--3{grid-template-columns:1fr 1fr 1fr}
@media(max-width:768px){.grid--2,.grid--3{grid-template-columns:1fr}}

/* ===== HEADER ===== */
.site-header{position:fixed;top:16px;left:16px;right:16px;z-index:1000;background:var(--color-dark-soft);backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);border-radius:var(--radius-md);box-shadow:var(--shadow-md);padding:0 20px;height:var(--header-height);display:flex;flex-direction:column;justify-content:center;max-width:calc(100% - 32px);margin:0 auto}
.site-header__inner{display:flex;align-items:center;justify-content:space-between;width:100%;position:relative}
.site-header__logo{font-family:var(--font-heading);font-weight:700;font-size:22px;letter-spacing:-0.02em;color:#fff;transition:color var(--transition);flex-shrink:0}
.site-header__logo:hover{color:var(--color-primary)}

/* ---- Navigation ---- */
.site-header__nav ul{display:flex;gap:4px;align-items:center}
.site-header__nav-link{display:block;padding:8px 18px;border-radius:var(--radius-lg);font-family:var(--font-heading);font-weight:400;font-size:14px;color:rgba(255,255,255,0.8);transition:background var(--transition),color var(--transition);white-space:nowrap}
.site-header__nav-link:hover{background:rgba(255,69,0,0.25);color:#fff}
.site-header__nav-link[aria-current="page"]{background:var(--color-primary);color:#fff;font-weight:500}
.site-header__cta{margin-left:20px;flex-shrink:0;font-size:14px;padding:8px 22px}

/* ---- Mobile Toggle ---- */
.nav-toggle{display:none;flex-direction:column;gap:5px;padding:8px;border-radius:var(--radius-sm);transition:background var(--transition)}
.nav-toggle span{display:block;width:24px;height:2px;background:#fff;border-radius:2px;transition:transform var(--transition),opacity var(--transition)}
.nav-toggle:hover{background:rgba(255,255,255,0.08)}

/* ---- Progress Bar ---- */
.progress-bar{position:absolute;bottom:0;left:0;height:3px;background:var(--color-primary);width:0%;border-radius:0 0 0 3px;transition:width 0.1s linear;will-change:width}
@media(prefers-reduced-motion:reduce){.progress-bar{transition:none}}

/* ---- Mobile States ---- */
@media(max-width:900px){
  .site-header{top:12px;left:12px;right:12px;padding:0 14px;max-width:calc(100% - 24px)}
  .site-header__nav{position:fixed;top:calc(var(--header-height) + 16px);left:12px;right:12px;background:var(--color-dark-soft);backdrop-filter:blur(12px);-webkit-backdrop-filter:blur(12px);border-radius:var(--radius-md);padding:16px 8px;box-shadow:var(--shadow-md);opacity:0;visibility:hidden;transform:translateY(-8px);transition:opacity 0.3s,visibility 0.3s,transform 0.3s;max-height:70vh;overflow-y:auto}
  .site-header__nav[data-open]{opacity:1;visibility:visible;transform:translateY(0)}
  .site-header__nav ul{flex-direction:column;gap:2px}
  .site-header__nav-link{padding:12px 20px;font-size:15px;width:100%;text-align:center}
  .site-header__cta{display:none}
  .nav-toggle{display:flex}
  .site-header__inner{justify-content:space-between}
}

/* ===== FOOTER ===== */
.site-footer{background:var(--color-dark);border-top:1px solid rgba(255,255,255,0.06);padding:48px 24px 32px;margin-top:80px}
.site-footer__inner{max-width:var(--container-max);margin:0 auto;display:grid;grid-template-columns:1fr 1.5fr 1fr;gap:40px 32px}
.site-footer__brand{grid-column:1}
.site-footer__contact{grid-column:2}
.site-footer__links{grid-column:3}
.site-footer__copyright{grid-column:1 / -1;border-top:1px solid rgba(255,255,255,0.08);padding-top:24px;margin-top:8px;display:flex;flex-wrap:wrap;justify-content:space-between;align-items:center;font-size:13px;color:var(--color-gray)}
.site-footer__logo{font-family:var(--font-heading);font-weight:700;font-size:20px;color:var(--color-primary);transition:color var(--transition)}
.site-footer__logo:hover{color:#fff}
.site-footer__tagline{font-size:13px;color:var(--color-gray);margin-top:6px;letter-spacing:0.04em}
.site-footer__heading{font-family:var(--font-heading);font-weight:500;font-size:15px;color:#fff;margin-bottom:14px;letter-spacing:0.03em}
.site-footer__contact ul,.site-footer__links ul{display:flex;flex-direction:column;gap:10px}
.site-footer__contact li,.site-footer__links li{font-size:14px;color:rgba(255,255,255,0.65);line-height:1.5}
.site-footer__contact a,.site-footer__links a{color:rgba(255,255,255,0.75);transition:color var(--transition)}
.site-footer__contact a:hover,.site-footer__links a:hover{color:var(--color-primary)}
.site-footer__note{font-size:12px;color:var(--color-gray);margin-top:12px;letter-spacing:0.02em}
.site-footer__copyright p{margin:2px 0}

@media(max-width:768px){
  .site-footer{padding:32px 16px 24px;margin-top:48px}
  .site-footer__inner{grid-template-columns:1fr;gap:28px}
  .site-footer__brand,.site-footer__contact,.site-footer__links{grid-column:1}
  .site-footer__copyright{flex-direction:column;align-items:flex-start;gap:6px;text-align:left}
}

/* ===== UTILITY ===== */
.text-primary{color:var(--color-primary)}
.text-green{color:var(--color-green)}
.text-red{color:var(--color-red)}
.text-gray{color:var(--color-gray)}
.bg-dark{background:var(--color-dark)}
.bg-light{background:var(--color-light);color:var(--color-dark)}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}

/* ===== IMAGE CONTAINER BASE ===== */
.img-frame{background:rgba(255,255,255,0.04);border-radius:var(--radius-md);overflow:hidden;position:relative;aspect-ratio:16/9;display:flex;align-items:center;justify-content:center;color:var(--color-gray);font-size:13px}
.img-frame--portrait{aspect-ratio:3/4}
.img-frame--hero{aspect-ratio:21/9}
.img-frame svg{width:48px;height:48px;opacity:0.2}

/* ===== RESPONSIVE TYPOGRAPHY ===== */
@media(max-width:480px){
  .site-header__logo{font-size:18px}
  .site-header__nav-link{padding:10px 14px;font-size:14px}
  .section__title{font-size:26px}
}