:root{--liner-edge:clamp(12px,4.6vw,19px)}
.back,.left,.right,.bottom,.flap-face,.flap-face.reverse{background-color:#161719;background-image:url('burgundy-paper.webp');background-blend-mode:soft-light;background-size:410px 512px}
.back{border-color:#0b0b0d;box-shadow:0 1px 0 #ffffff24 inset,0 -2px 0 #0009 inset,2px 3px 2px #0003,0 14px 20px #0003}
.back:before,.flap-face.reverse:before{content:'';position:absolute;inset:var(--liner-edge);background:linear-gradient(118deg,#8c5c19 0%,#bb8a32 9%,#f0d28b 20%,#fff2bf 25%,#cea04c 31%,#9b6d24 44%,#e7c06a 60%,#fff1b0 67%,#c29136 74%,#825414 100%);box-shadow:inset 0 0 0 1px #f2d98e80,inset 0 2px 5px #67411333;pointer-events:none}
.back:before{border-radius:1px}
.flap-face.reverse:before{clip-path:polygon(0 0,100% 0,100% 54%,50% 100%,0 54%)}
.flap-face:after{background:linear-gradient(180deg,#ffffff30 0,transparent 2px,transparent 98%,#0008)}
.flap-face.reverse:after{inset:var(--liner-edge);clip-path:polygon(0 0,100% 0,100% 54%,50% 100%,0 54%);background:linear-gradient(112deg,transparent 18%,#fff8 24%,transparent 32%,transparent 62%,#fff5 67%,transparent 74%);mix-blend-mode:soft-light}
.pocket{filter:drop-shadow(0 -1px 1px #ffffff20) drop-shadow(0 -5px 4px #0007)}
.flap{filter:drop-shadow(0 1px 1px #000a) drop-shadow(0 8px 6px #0008)}
.cover-copy{text-shadow:0 -1px #000,0 1px #ffffff18}.sender{text-shadow:0 -1px #000}.seal{filter:drop-shadow(1px 5px 3px #0009)}.seal:hover{filter:drop-shadow(1px 5px 3px #0009) brightness(1.06)}
.opened .flap{transform:translateY(190px) rotateX(178deg)}
.flap{height:61%;transform-style:flat;filter:drop-shadow(0 2px 1px #000b) drop-shadow(0 9px 7px #000a)}
.flap-face,.flap-face.reverse{clip-path:polygon(0 0,100% 0,50% 100%);backface-visibility:visible}
.flap-face.reverse{transform:none;opacity:0}
.inside-visible .flap-face:not(.reverse){opacity:0}
.inside-visible .flap-face.reverse{opacity:1}
.flap-face.reverse:before,.flap-face.reverse:after{clip-path:polygon(0 0,100% 0,50% 100%);inset:var(--liner-edge) var(--liner-edge) calc(var(--liner-edge) * 1.6)}
.left{background-image:linear-gradient(135deg,#ffffff13,#0004),url('burgundy-paper.webp');background-blend-mode:normal,soft-light}
.right{background-image:linear-gradient(225deg,#ffffff0a,#0008),url('burgundy-paper.webp');background-blend-mode:normal,soft-light}
.bottom{background-image:linear-gradient(180deg,#ffffff16,transparent 20%,#0005),url('burgundy-paper.webp');background-blend-mode:normal,soft-light}
.seams{position:absolute;inset:0;width:100%;height:100%;overflow:visible;pointer-events:none}
/* One paper finish outside, one continuous foil sheet across the hinge. */
.flap-face:not(.reverse){background-image:linear-gradient(180deg,#ffffff16,transparent 20%,#0005),url('burgundy-paper.webp');background-blend-mode:normal,soft-light;background-position:center bottom;background-size:410px 512px}
.back:before,.flap-face.reverse:before{background:linear-gradient(90deg,#91621e 0%,#c39343 11%,#f0d28b 23%,#fff0b7 29%,#d0a24e 37%,#a4772c 49%,#e3ba60 65%,#fff1b0 72%,#c4943c 83%,#8f611c 100%);box-shadow:none}
.back:before{top:-1px;border-radius:0}
.flap-face.reverse:before,.flap-face.reverse:after{top:0}
.flap-face.reverse:after{background:linear-gradient(90deg,transparent 20%,#fff4 28%,transparent 37%,transparent 65%,#fff3 72%,transparent 82%)}
.inside-visible{filter:none}
.opened .flap{transform:translateY(190px) rotateX(180deg)}
/* Preserve the original lower fold; mirror its geometry on the upper flap. */
.flap{height:56%;filter:drop-shadow(0 2px 1px #000b) drop-shadow(0 9px 7px #000a)}
.flap-face,.flap-face.reverse{clip-path:polygon(0 0,100% 0,100% 53.5714%,50% 100%,0 53.5714%)}
.flap-face.reverse:before,.flap-face.reverse:after{clip-path:polygon(0 0,100% 0,100% 53.5714%,50% 100%,0 53.5714%)}
.bottom{clip-path:polygon(0 100%,0 70%,50% 44%,100% 70%,100% 100%)}
.left{clip-path:polygon(0 0,58% 59%,0 100%)}
.right{clip-path:polygon(100% 0,42% 59%,100% 100%)}
.pocket{filter:drop-shadow(0 -1px 1px #ffffff20) drop-shadow(0 -5px 4px #0007)}
.seal{top:53%}
.inside-visible{filter:none}