/* ===== Reset & Base ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body { font-family: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif; font-weight: 400; line-height: 1.75; color: #1A1A1A; background: #FFFFFF; }
a { color: inherit; text-decoration: none; }
ul, ol { list-style: none; }
img { max-width: 100%; display: block; }
button { font: inherit; cursor: pointer; border: none; background: none; }
:focus-visible { outline: 3px solid #FF6B35; outline-offset: 2px; }

/* ===== CSS Variables ===== */
:root {
  --color-primary: #0B1D3A;
  --color-primary-light: #1C3A6E;
  --color-accent-orange: #FF6B35;
  --color-accent-green: #00C9A7;
  --color-white: #FFFFFF;
  --color-gray: #F4F4F4;
  --color-dark: #1A1A1A;
  --color-border: #E0E0E0;
  --font-mono: "Courier New", Courier, monospace;
  --container-max: 1200px;
  --container-padding: 24px;
  --header-height: 72px;
  --transition-fast: 0.2s ease;
  --transition-med: 0.35s ease;
  --shadow-card: 0 2px 12px rgba(0,0,0,0.06), 0 8px 32px rgba(0,0,0,0.04);
  --shadow-stack: 0 1px 4px rgba(0,0,0,0.04), 0 4px 16px rgba(0,0,0,0.06), 0 12px 48px rgba(0,0,0,0.04);
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; scroll-behavior: auto !important; }
}

/* ===== Container ===== */
.container { max-width: var(--container-max); margin: 0 auto; padding-left: var(--container-padding); padding-right: var(--container-padding); }

/* ===== Skip Link ===== */
.skip-link { position: absolute; top: -100%; left: 16px; z-index: 10000; padding: 8px 16px; background: var(--color-primary); color: var(--color-white); font-weight: 700; border-radius: 0 0 6px 6px; transition: top var(--transition-fast); }
.skip-link:focus { top: 0; }

/* ===== Scroll Progress ===== */
.scroll-progress { position: fixed; top: 0; left: 0; z-index: 9999; width: 0%; height: 4px; background: var(--color-accent-orange); transition: width 0.1s linear; pointer-events: none; }
@media (prefers-reduced-motion: reduce) {
  .scroll-progress { transition: none; }
}

/* ===== Site Header ===== */
.site-header { position: fixed; top: 0; left: 0; right: 0; z-index: 9000; height: var(--header-height); transition: background var(--transition-med), box-shadow var(--transition-med); }
.site-header[data-nav-state="transparent"] { background: transparent; box-shadow: none; }
.site-header[data-nav-state="solid"] { background: var(--color-primary); box-shadow: 0 2px 20px rgba(0,0,0,0.15); }
.header-inner { display: flex; align-items: center; height: var(--header-height); gap: 16px; }
.site-brand { font-size: 1.5rem; font-weight: 700; color: var(--color-white); letter-spacing: 0.04em; white-space: nowrap; }
.site-header[data-nav-state="transparent"] .site-brand { color: var(--color-white); }
.site-header[data-nav-state="solid"] .site-brand { color: var(--color-white); }

/* ===== Navigation Toggle ===== */
.nav-toggle { display: none; flex-direction: column; justify-content: center; align-items: center; width: 44px; height: 44px; margin-left: auto; gap: 5px; background: transparent; border: none; cursor: pointer; }
.nav-toggle-bar { display: block; width: 26px; height: 3px; background: var(--color-white); border-radius: 2px; transition: transform var(--transition-fast), opacity var(--transition-fast); }
.site-header[data-nav-state="transparent"] .nav-toggle-bar { background: var(--color-white); }
.site-header[data-nav-state="solid"] .nav-toggle-bar { background: var(--color-white); }

/* ===== Site Nav ===== */
.site-nav { display: flex; align-items: center; }
.nav-list { display: flex; gap: 8px; }
.nav-item { margin: 0; }
.nav-link { display: block; padding: 8px 16px; font-size: 0.95rem; font-weight: 500; color: var(--color-white); border-radius: 6px; transition: background var(--transition-fast), color var(--transition-fast); white-space: nowrap; }
.site-header[data-nav-state="transparent"] .nav-link { color: var(--color-white); }
.site-header[data-nav-state="solid"] .nav-link { color: var(--color-white); }
.nav-link:hover { background: rgba(255,255,255,0.12); }
.nav-link[aria-current="page"] { background: rgba(255,107,53,0.25); color: var(--color-accent-orange); font-weight: 700; }
.nav-link[aria-current="page"]::before { content: "◆ "; font-size: 0.7em; }

/* ===== CTA Button ===== */
.btn-cta { display: inline-flex; align-items: center; justify-content: center; padding: 10px 24px; font-size: 0.95rem; font-weight: 700; color: var(--color-white); background: var(--color-accent-orange); border-radius: 6px; transition: background var(--transition-fast), transform var(--transition-fast); white-space: nowrap; margin-left: auto; }
.btn-cta:hover { background: #e85d2a; transform: translateY(-1px); }
.site-header[data-nav-state="transparent"] .btn-cta { box-shadow: 0 2px 12px rgba(255,107,53,0.3); }
.site-header[data-nav-state="solid"] .btn-cta { box-shadow: 0 2px 12px rgba(255,107,53,0.3); }

/* ===== Mobile Nav ===== */
@media (max-width: 767px) {
  .nav-toggle { display: flex; }
  .btn-cta { display: none; }
  .site-nav { position: fixed; top: var(--header-height); left: 0; right: 0; bottom: 0; z-index: 9500; background: var(--color-primary); padding: 24px 32px; transform: translateX(100%); transition: transform var(--transition-med); overflow-y: auto; align-items: flex-start; }
  .site-nav[data-open] { transform: translateX(0); }
  .nav-list { flex-direction: column; gap: 4px; width: 100%; }
  .nav-link { padding: 14px 20px; font-size: 1.1rem; border-radius: 8px; }
  .nav-link[aria-current="page"] { background: rgba(255,107,53,0.2); }
  .site-header[data-nav-state="solid"] .site-nav { background: var(--color-primary); }
  .mobile-cta { display: block; margin-top: 24px; width: 100%; text-align: center; background: var(--color-accent-orange); color: var(--color-white); padding: 14px; border-radius: 8px; font-weight: 700; }
}

@media (min-width: 768px) {
  .mobile-cta { display: none; }
}

/* ===== Site Footer ===== */
.site-footer { background: var(--color-primary); color: var(--color-white); padding: 48px 0 24px; margin-top: 80px; }
.footer-inner { display: grid; grid-template-columns: 1fr 1fr; gap: 32px 48px; }
.footer-brand-section { grid-column: 1 / 2; }
.footer-brand { font-size: 1.6rem; font-weight: 700; letter-spacing: 0.04em; display: block; margin-bottom: 8px; }
.footer-tagline { font-size: 0.9rem; color: rgba(255,255,255,0.6); line-height: 1.5; }
.footer-info { grid-column: 2 / 3; text-align: right; }
.footer-contact { font-size: 0.95rem; line-height: 1.6; color: rgba(255,255,255,0.85); }
.footer-contact a { color: var(--color-accent-orange); transition: color var(--transition-fast); }
.footer-contact a:hover { color: #ff8a5c; }
.footer-address { font-size: 0.85rem; color: rgba(255,255,255,0.5); margin-top: 6px; }
.footer-links { grid-column: 1 / 3; display: flex; align-items: center; justify-content: center; gap: 12px; padding-top: 20px; border-top: 1px solid rgba(255,255,255,0.1); }
.footer-link { font-size: 0.9rem; color: rgba(255,255,255,0.7); transition: color var(--transition-fast); }
.footer-link:hover { color: var(--color-accent-orange); }
.footer-link-sep { color: rgba(255,255,255,0.25); font-size: 0.85rem; }
.footer-icp { grid-column: 1 / 3; text-align: center; font-size: 0.8rem; color: rgba(255,255,255,0.4); padding-top: 12px; }

/* ===== Trust Bar ===== */
.trust-bar { background: var(--color-accent-orange); padding: 10px 0; margin-top: 32px; }
.trust-bar-inner { display: flex; align-items: center; justify-content: center; gap: 8px; flex-wrap: wrap; }
.trust-icon { font-size: 1.1rem; flex-shrink: 0; }
.trust-text { font-size: 0.85rem; font-weight: 500; color: var(--color-white); text-align: center; }

/* ===== Shared Components ===== */

/* Card */
.card { background: var(--color-white); border-radius: 8px; padding: 24px; box-shadow: var(--shadow-card); transition: box-shadow var(--transition-fast), transform var(--transition-fast); }
.card:hover { box-shadow: var(--shadow-stack); transform: translateY(-2px); }

/* Tag (印刷边框标签) */
.tag { display: inline-flex; align-items: center; padding: 4px 14px; font-size: 0.8rem; font-weight: 600; color: var(--color-primary); border: 2px solid var(--color-primary); background: var(--color-white); letter-spacing: 0.03em; }
.tag-orange { border-color: var(--color-accent-orange); color: var(--color-accent-orange); }
.tag-green { border-color: var(--color-accent-green); color: var(--color-accent-green); }

/* Index Mono (等宽索引) */
.index-mono { font-family: var(--font-mono); font-size: 1.4rem; font-weight: 700; color: var(--color-accent-orange); line-height: 1.2; }
.index-mono-sm { font-size: 1rem; }
.index-mono-lg { font-size: 2rem; }

/* Print Border (印刷边框装饰块) */
.print-border { border: 2px solid var(--color-primary); padding: 20px; position: relative; background: var(--color-white); }
.print-border::before { content: ""; position: absolute; top: 4px; left: 4px; right: -4px; bottom: -4px; background: var(--color-primary); z-index: -1; }

/* Paper Stack (纸张叠层) */
.paper-stack { position: relative; background: var(--color-white); padding: 24px; box-shadow: 0 1px 4px rgba(0,0,0,0.04), 0 4px 16px rgba(0,0,0,0.06), 0 12px 48px rgba(0,0,0,0.04); }
.paper-stack::after { content: ""; position: absolute; left: 8px; right: 8px; bottom: -6px; height: 12px; background: rgba(0,0,0,0.03); border-radius: 0 0 4px 4px; z-index: -1; box-shadow: 0 2px 8px rgba(0,0,0,0.04); }

/* Button Base */
.btn { display: inline-flex; align-items: center; justify-content: center; padding: 10px 28px; font-size: 0.95rem; font-weight: 600; border-radius: 6px; transition: background var(--transition-fast), color var(--transition-fast), transform var(--transition-fast); }
.btn-primary { background: var(--color-primary); color: var(--color-white); }
.btn-primary:hover { background: var(--color-primary-light); transform: translateY(-1px); }
.btn-orange { background: var(--color-accent-orange); color: var(--color-white); }
.btn-orange:hover { background: #e85d2a; transform: translateY(-1px); }
.btn-outline { border: 2px solid var(--color-primary); color: var(--color-primary); background: transparent; }
.btn-outline:hover { background: var(--color-primary); color: var(--color-white); }

/* Section Title & Number */
.section-title { font-size: 2rem; font-weight: 700; color: var(--color-primary); line-height: 1.3; margin-bottom: 16px; }
.section-number { font-family: var(--font-mono); font-size: 1.2rem; font-weight: 700; color: var(--color-accent-orange); display: block; margin-bottom: 8px; }

/* Responsive Footer */
@media (max-width: 767px) {
  .footer-inner { grid-template-columns: 1fr; gap: 20px; }
  .footer-brand-section { grid-column: 1; text-align: center; }
  .footer-info { grid-column: 1; text-align: center; }
  .footer-links { grid-column: 1; flex-wrap: wrap; justify-content: center; }
  .footer-icp { grid-column: 1; }
  .trust-text { font-size: 0.8rem; }
}

@media (min-width: 768px) and (max-width: 1023px) {
  .footer-inner { gap: 24px 32px; }
}

/* ===== Image Container Base ===== */
.img-container { position: relative; overflow: hidden; background: var(--color-gray); }
.img-container img { width: 100%; height: 100%; object-fit: cover; }
.img-ratio-16-9 { aspect-ratio: 16 / 9; }
.img-ratio-4-3 { aspect-ratio: 4 / 3; }
.img-ratio-1-1 { aspect-ratio: 1 / 1; }

/* ===== Breadcrumb ===== */
.breadcrumb { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; padding: 16px 0; font-size: 0.85rem; color: rgba(255,255,255,0.6); }
.breadcrumb a { color: rgba(255,255,255,0.8); transition: color var(--transition-fast); }
.breadcrumb a:hover { color: var(--color-accent-orange); }
.breadcrumb .sep { color: rgba(255,255,255,0.3); }

/* ===== Utility ===== */
.text-center { text-align: center; }
.mt-1 { margin-top: 16px; }
.mt-2 { margin-top: 32px; }
.mt-3 { margin-top: 48px; }
.mb-1 { margin-bottom: 16px; }
.mb-2 { margin-bottom: 32px; }
.mb-3 { margin-bottom: 48px; }