/* 由 scripts/build-home.mjs 抽出，勿手改。
 * 用法：容器要 position:relative + overflow:hidden（.secbg-host 已含），內容層 z-index ≥ 2。
 * <div class="secbg-host">
 *   <video class="sec-bg sec-bg--light" src="/home/assets/section-bg-loop-seamless.mp4" autoplay loop muted playsinline poster="/home/assets/section-bg.jpg"></video>
 *   <video class="sec-bg sec-bg--dark"  src="/home/assets/section-bg-dark.mp4"          autoplay loop muted playsinline poster="/home/assets/section-bg-dark.jpg"></video>
 *   <div class="sec-bg-veil"></div>
 *   <div style="position:relative;z-index:2">…內容…</div>
 * </div>
 * 深淺切換＝CSS 靠 html[data-theme] 顯隱（與首頁同機制）。
 * 首頁另有「只載當前主題」的省流量載法（data-video-src＋loader），子頁要用再說。 */
.secbg-host{position:relative;overflow:hidden;}
.sec-bg{position:absolute;inset:0;z-index:0;width:100%;height:100%;object-fit:cover;}
.sec-bg--dark{display:none;}
.sec-bg-veil{position:absolute;inset:0;z-index:1;background:linear-gradient(180deg,rgba(247,246,251,.46),rgba(247,246,251,.6));}
[data-theme="dark"] .sec-bg--light{display:none;}
[data-theme="dark"] .sec-bg--dark{display:block;}
[data-theme="dark"] .sec-bg-veil{background:radial-gradient(125% 108% at 50% 48%, rgba(30,27,40,.82) 0%, rgba(30,27,40,.62) 56%, rgba(30,27,40,.5) 100%);}
@media (prefers-reduced-motion:reduce){ .secbg-host .sec-bg{display:none;} .secbg-host{background:var(--surface-sunken,#f1eff7);} }