#slide,.print-slide{isolation:isolate}
#slide::before,.print-slide::before{
  content:"";position:absolute;inset:0;z-index:-2;pointer-events:none;
  background-image:var(--slide-bg,none);background-size:cover;background-position:center;
  opacity:var(--slide-bg-opacity,.3)
}
#slide::after,.print-slide::after{
  content:"";position:absolute;inset:0;z-index:-1;pointer-events:none;
  background:linear-gradient(90deg,rgba(11,13,16,.45),rgba(11,13,16,.16) 48%,rgba(11,13,16,.42)),
    linear-gradient(180deg,rgba(11,13,16,.05),rgba(11,13,16,.18));
  opacity:var(--slide-shade-opacity,1)
}

#slide[data-slide-id="P3"],.print-slide[data-slide-id="P3"]{--slide-bg:url("assets/backgrounds/P3.webp");--slide-bg-opacity:.74}
#slide[data-slide-id="T1"],.print-slide[data-slide-id="T1"]{--slide-bg:url("assets/backgrounds/T1.webp");--slide-bg-opacity:.72}
#slide[data-slide-id="S1"],.print-slide[data-slide-id="S1"]{--slide-bg:url("assets/backgrounds/S1.webp");--slide-bg-opacity:.68}
#slide[data-slide-id="L1-3"],.print-slide[data-slide-id="L1-3"]{--slide-bg:url("assets/backgrounds/L1-3.webp");--slide-bg-opacity:.52}
#slide[data-slide-id="L1-5c"],.print-slide[data-slide-id="L1-5c"]{--slide-bg:url("assets/backgrounds/L1-5c.webp");--slide-bg-opacity:.42}
#slide[data-slide-id="L1-4"],.print-slide[data-slide-id="L1-4"]{--slide-bg:url("assets/backgrounds/L1-4.webp");--slide-bg-opacity:.42}
#slide[data-slide-id="L1-4b"],.print-slide[data-slide-id="L1-4b"]{--slide-bg:url("assets/backgrounds/L1-4b.webp");--slide-bg-opacity:.34}
#slide[data-slide-id="L3-2a"],.print-slide[data-slide-id="L3-2a"]{--slide-bg:url("assets/backgrounds/L3-2a.webp");--slide-bg-opacity:.42}
#slide[data-slide-id="L1-3a"],.print-slide[data-slide-id="L1-3a"]{--slide-bg:url("assets/backgrounds/L1-3a.webp");--slide-bg-opacity:.68}
#slide[data-slide-id="L1-3b"],.print-slide[data-slide-id="L1-3b"]{--slide-bg:url("assets/backgrounds/L1-3b.webp");--slide-bg-opacity:.5}
#slide[data-slide-id="L1-6b3"],.print-slide[data-slide-id="L1-6b3"]{--slide-bg:url("assets/backgrounds/L1-6b3.webp");--slide-bg-opacity:.56}
#slide[data-slide-id="L1-6b3v"],.print-slide[data-slide-id="L1-6b3v"]{--slide-bg:url("assets/backgrounds/L1-6b3v.webp");--slide-bg-opacity:.42}
#slide[data-slide-id="L1-6b4"],.print-slide[data-slide-id="L1-6b4"]{--slide-bg:url("assets/backgrounds/L1-6b4.webp");--slide-bg-opacity:.5}
#slide[data-slide-id="Z2"],.print-slide[data-slide-id="Z2"]{--slide-bg:url("assets/backgrounds/Z2.webp");--slide-bg-opacity:.58}
#slide[data-slide-id="Z3"],.print-slide[data-slide-id="Z3"]{--slide-bg:url("assets/backgrounds/Z3.webp");--slide-bg-opacity:.42}
#slide[data-slide-id="P54"],.print-slide[data-slide-id="P54"]{--slide-bg:url("assets/backgrounds/P54.webp");--slide-bg-opacity:.72}
#slide[data-slide-id="A1"],.print-slide[data-slide-id="A1"]{--slide-bg:url("assets/backgrounds/A1.webp");--slide-bg-opacity:.36}
/* TODO A3 暂时复用 A2 的图,待生成专属语义配图 */

@media (prefers-reduced-transparency:reduce){
  #slide::before,.print-slide::before{opacity:.12}
}