/* Màn "Chạm để mở thiệp": khách chạm là nhạc bắt đầu to dần và thiệp mở ra.
   Chỉ hiện khi có JS (html.js); tự ẩn nếu cover.js không chạy được (html.no-cover). */
.cover { display: none; }
.js .cover {
  position: fixed; inset: 0; z-index: 60;
  display: grid; place-items: center;
  padding: max(28px, env(safe-area-inset-top, 0px)) 24px max(28px, env(safe-area-inset-bottom, 0px));
  overflow: hidden;
  color: #fff; text-align: center;
  background: #13241a;
  cursor: pointer;
  touch-action: none; /* không cho vuốt cuộn trang phía sau khi thiệp chưa mở */
  transition: opacity 1s var(--ease), visibility 0s linear 1s;
}
.js.no-cover .cover, .js .cover[hidden] { display: none; }
.cover__bg {
  position: absolute; inset: -60px;
  background: url(../img/hero.webp) 58% 30% / cover no-repeat;
  filter: blur(18px) brightness(.62) saturate(1.05);
}
.cover__bg::after { content: ''; position: absolute; inset: 0; background: radial-gradient(ellipse at 50% 42%, rgba(5, 40, 20, .2), rgba(5, 30, 16, .72)); }
.cover__inner { position: relative; display: grid; justify-items: center; gap: 12px; max-width: 440px; transition: transform 1s var(--ease-out); }
.cover__inner > * { animation: blur-in 1.3s var(--ease) both; animation-delay: calc(.15s + var(--i, 0) * .18s); }
.cover__logo { width: 104px; height: auto; filter: brightness(0) invert(1); opacity: .95; }
.cover__inner > .cover__logo { animation-name: rise-in; } /* blur-in đổi filter nên sẽ làm mất màu trắng của logo */
@keyframes rise-in { from { opacity: 0; transform: translate3d(0, 18px, 0); } to { opacity: .95; transform: none; } }
.cover__kicker { margin-top: 10px; font: 400 12px/1 var(--serif); letter-spacing: .44em; padding-left: .44em; opacity: .9; }
.cover__names { font: 400 clamp(42px, 12.5vw, 68px)/1.08 var(--script); text-shadow: 0 2px 18px rgba(0, 0, 0, .35); }
.cover__names span { display: block; }
.cover__date { font: 400 17px/1 var(--serif); letter-spacing: .34em; padding-left: .34em; }
.cover__btn {
  margin-top: 26px;
  display: inline-flex; align-items: center; gap: 12px;
  padding: 15px 30px;
  border: 1px solid rgba(255, 255, 255, .85); border-radius: 999px;
  background: rgba(255, 255, 255, .1); color: #fff;
  font: 600 13px/1 var(--sans); letter-spacing: .3em;
  cursor: pointer;
  -webkit-backdrop-filter: blur(4px); backdrop-filter: blur(4px);
}
.cover__inner > .cover__btn {
  animation: blur-in 1.3s var(--ease) both, breathe 2.6s ease-in-out infinite;
  animation-delay: calc(.15s + var(--i, 0) * .18s), 2.2s;
}
.cover__btn svg { width: 18px; height: 18px; fill: currentColor; }
.cover__btn:focus-visible { outline: 2px solid #fff; outline-offset: 4px; }
.cover__hint { margin-top: 4px; font-size: 12px; opacity: .75; }
@keyframes breathe {
  0%, 100% { box-shadow: 0 0 0 0 rgba(255, 255, 255, .35); }
  50% { box-shadow: 0 0 0 14px rgba(255, 255, 255, 0); }
}
.cover.is-leaving { opacity: 0; visibility: hidden; pointer-events: none; }
.cover.is-leaving .cover__inner { transform: translateY(-28px) scale(.98); }
html.cover-open { overflow: hidden; }