.opening{
  min-height:100svh;
  display:grid;
  place-items:center;
  padding:28px 24px;
  position:relative;
  text-align:center;
  overflow:hidden;
}
.opening > div{
  width:min(96vw,760px);
  margin:auto;
}
.intro-title{
  margin-bottom:22px;
  color:rgba(255,255,255,.88);
  font-size:clamp(15px,2vw,19px);
  font-weight:300;
  letter-spacing:.09em;
  text-transform:uppercase;
  line-height:1.55;
}
.envelope-stage{
  width:min(94vw,720px);
  margin-inline:auto;
  cursor:pointer;
  filter:drop-shadow(0 30px 45px rgba(0,0,0,.35));
}
.envelope-svg{
  display:block;
  width:100%;
  height:auto;
}
.open-hint{
  margin-top:20px;
  color:var(--gold);
  font-family:var(--font-title);
  font-size:clamp(13px,1.8vw,15px);
  letter-spacing:.12em;
  text-transform:uppercase;
  line-height:1.6;
}
.seal-shine{animation:sealGlow 2.5s ease-in-out infinite}
@keyframes sealGlow{50%{filter:brightness(1.25)}}
@media(max-width:560px){
  .opening{padding:20px 14px}
  .opening > div{width:100%}
  .intro-title{font-size:16px;margin-bottom:18px;letter-spacing:.075em}
  .envelope-stage{width:calc(100vw - 30px);max-width:500px}
  .open-hint{font-size:13px;margin-top:16px;letter-spacing:.08em}
}