/* 项目页顶栏（2026-10-09）：和首页同一套导航——左边名字的位置换成「← 返回」，右边 Work / About / Contact / Resume；
   透明无底、差值混合（浅底上显深、深底上显白），字号和首页 .h3-top 一致 */
header.cn-top { position: sticky; top: 0; z-index: 100; display: grid; grid-template-columns: repeat(12, 1fr); align-items: start; padding: 38px 56px 14px; background: none !important; border: 0 !important; -webkit-backdrop-filter: none !important; backdrop-filter: none !important; mix-blend-mode: difference; min-height: 0; gap: 0; pointer-events: none; }
header.cn-top > * { padding: 0 8px; }
header.cn-top .cn-back { grid-column: 1 / span 4; justify-self: start; pointer-events: auto; display: inline-flex; align-items: center; gap: 8px; font: 600 22px/24px "Inter", "Noto Sans SC", sans-serif; letter-spacing: -.02em; color: #FAFAFA; text-decoration: none; white-space: nowrap; transition: opacity .2s ease; }
header.cn-top .cn-back svg { width: 24px; height: 24px; }
header.cn-top .cn-nav { grid-column: 9 / span 4; display: flex; justify-content: space-between; }
header.cn-top .cn-nav a { pointer-events: auto; font: 400 16px/24px ui-monospace, "SF Mono", Menlo, Consolas, monospace; text-transform: uppercase; color: #FAFAFA; text-decoration: none; transition: opacity .2s ease; }
header.cn-top a:hover { opacity: .5; }
header.cn-top .cn-sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; margin: 0; padding: 0; }
@media (max-width: 1279px) { header.cn-top .cn-nav { grid-column: 7 / span 6; } }
@media (max-width: 1100px) { header.cn-top { padding: 38px 16px 14px; grid-template-columns: 1fr auto; } header.cn-top .cn-back { grid-column: 1; } header.cn-top .cn-nav { grid-column: 2; gap: 20px; } }
@media (max-width: 640px) { header.cn-top { padding-top: 22px; } header.cn-top .cn-back { font-size: 18px; line-height: 22px; } header.cn-top .cn-back svg { width: 20px; height: 20px; } header.cn-top .cn-nav { gap: 10px; } header.cn-top .cn-nav a { font-size: 11px; line-height: 22px; } }