:root{
  --wine:#22050d; --deep:#0b0105; --rose:#c8102e; --pink:#ff9fb5; --gold:#ffd9a8; --cream:#fff4f0;
  --script:'Dancing Script','Brush Script MT',cursive;
  --body:'Be Vietnam Pro','Segoe UI',system-ui,sans-serif;
}
*{box-sizing:border-box;margin:0;padding:0}
html,body{height:100%;overflow:hidden}
body{
  background:radial-gradient(ellipse at 50% 20%,#4a0c1c 0%,var(--wine) 45%,var(--deep) 100%);
  color:var(--cream);font-family:var(--body);-webkit-tap-highlight-color:transparent;user-select:none;
}
canvas{position:fixed;inset:0;width:100%;height:100%;display:block}
#garden{z-index:1}
#vignette{position:fixed;inset:0;z-index:2;pointer-events:none;
  background:radial-gradient(ellipse at 50% 45%,transparent 45%,rgba(0,0,0,.55) 100%)}
#petals{z-index:4;pointer-events:none}

/* ---------- Màn mở đầu ---------- */
#intro{
  position:fixed;inset:0;z-index:10;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:18px;
  text-align:center;padding:24px;transition:opacity 1.2s ease, visibility 1.2s;
}
#intro.hide{opacity:0;visibility:hidden}
#intro h1{font-family:var(--script);font-weight:700;font-size:clamp(2.4rem,8vw,4.6rem);color:var(--gold);
  text-shadow:0 0 24px rgba(255,143,171,.45);animation:float 4s ease-in-out infinite}
#intro p{font-weight:300;letter-spacing:.08em;opacity:.85;animation:blink 2.4s ease-in-out infinite}
#openBtn{background:none;border:0;cursor:pointer;line-height:0;border-radius:50%;
  filter:drop-shadow(0 10px 30px rgba(200,16,46,.7));animation:pulse 1.8s ease-in-out infinite}
#openBtn img{width:clamp(170px,42vw,280px);height:auto}
#openBtn:focus-visible{outline:2px dashed var(--gold);outline-offset:6px}

/* ---------- Trái tim kết bằng hoa hồng ---------- */
#heart{
  --S:min(82vw,58vh);
  position:fixed;left:50%;top:50%;width:var(--S);height:var(--S);z-index:5;pointer-events:none;
  transform:translate(-50%,-50%);transition:transform 1.6s cubic-bezier(.65,0,.35,1);
}
#heart.up{transform:translate(-50%,calc(-50% - 50vh + var(--S)*.25 + 2vh)) scale(.46)}
#heart .inner{position:absolute;inset:0}
#heart .r{
  position:absolute;width:calc(var(--S)*var(--w));height:auto;
  transform:translate(-50%,-50%) scale(0) rotate(-160deg);opacity:0;
  filter:drop-shadow(0 4px 6px rgba(0,0,0,.55));
}
#heart.show .r{animation:pop .8s cubic-bezier(.2,1.5,.4,1) forwards;animation-delay:var(--d)}
#heart.beat .inner{animation:beat 1.3s ease-in-out infinite}
#heart .date{
  position:absolute;left:50%;top:44%;transform:translate(-50%,-50%) scale(.3);opacity:0;z-index:2;
  font-family:var(--script);font-weight:700;font-size:calc(var(--S)*.2);color:var(--gold);white-space:nowrap;
  text-shadow:0 2px 6px rgba(0,0,0,.8),0 0 30px rgba(200,16,46,.9);transition:all 1.2s ease;
}
#heart.beat .date{opacity:1;transform:translate(-50%,-50%) scale(1)}

/* ---------- Thiệp ---------- */
#card{
  position:fixed;z-index:6;left:50%;top:30vh;max-height:calc(70vh - max(4vh,env(safe-area-inset-bottom)));
  width:min(600px,calc(100vw - 32px));transform:translate(-50%,30px);opacity:0;visibility:hidden;
  display:flex;flex-direction:column;gap:14px;padding:26px clamp(20px,5vw,40px);
  background:linear-gradient(160deg,rgba(40,4,14,.62),rgba(20,2,8,.55));
  border:1px solid rgba(255,217,168,.3);border-radius:22px;
  backdrop-filter:blur(12px);-webkit-backdrop-filter:blur(12px);
  box-shadow:0 20px 60px rgba(0,0,0,.55),inset 0 0 40px rgba(255,159,181,.06);
  transition:all 1.1s ease;overflow-y:auto;overscroll-behavior:contain;scrollbar-width:none;
}
#card::-webkit-scrollbar{display:none}
#card>*{flex-shrink:0}
#card.show{opacity:1;visibility:visible;transform:translate(-50%,0)}
#card h2{font-family:var(--script);font-size:clamp(2rem,6vw,2.8rem);color:var(--gold);line-height:1.1}
#msg{font-size:clamp(.98rem,2.6vw,1.1rem);line-height:1.85;font-weight:300;white-space:pre-wrap;min-height:6em}
#msg .cur{display:inline-block;width:2px;height:1.1em;background:var(--pink);vertical-align:-3px;margin-left:2px;animation:blink .8s steps(1) infinite}
#sign{font-family:var(--script);font-size:clamp(1.6rem,5vw,2.2rem);color:var(--pink);text-align:right;opacity:0;transform:translateY(8px);transition:all 1s ease}
#sign.show{opacity:1;transform:none}
.actions{display:flex;gap:10px;flex-wrap:wrap;justify-content:center;opacity:0;transition:opacity 1s ease .4s}
.actions.show{opacity:1}
.actions button{
  font:500 .95rem var(--body);color:var(--wine);background:linear-gradient(135deg,var(--gold),var(--pink));
  border:0;border-radius:999px;padding:11px 20px;cursor:pointer;box-shadow:0 6px 20px rgba(200,16,46,.4);
  transition:transform .2s ease,box-shadow .2s ease;
}
.actions button:hover{transform:translateY(-2px) scale(1.04);box-shadow:0 10px 26px rgba(200,16,46,.6)}
.actions button:focus-visible{outline:2px solid var(--cream);outline-offset:3px}

/* ---------- Nút nhạc ---------- */
#music{
  position:fixed;z-index:11;right:max(16px,env(safe-area-inset-right));top:max(16px,env(safe-area-inset-top));
  width:46px;height:46px;border-radius:50%;border:1px solid rgba(255,217,168,.4);background:rgba(255,255,255,.08);
  color:var(--gold);font-size:1.2rem;cursor:pointer;display:none;backdrop-filter:blur(6px);
}
#music.on{animation:spin 6s linear infinite}

/* ---------- Hiệu ứng rơi / bay ---------- */
.fly{position:fixed;z-index:7;pointer-events:none;will-change:transform,opacity}
.heartUp{color:var(--pink);text-shadow:0 0 10px rgba(255,80,120,.8);animation:rise var(--t) ease-out forwards}
.roseFall{top:-140px;height:auto;filter:drop-shadow(0 6px 8px rgba(0,0,0,.5));animation:fall var(--t) linear forwards}

@keyframes pulse{0%,100%{transform:scale(1)}50%{transform:scale(1.07)}}
@keyframes float{0%,100%{transform:translateY(0)}50%{transform:translateY(-10px)}}
@keyframes blink{0%,100%{opacity:1}50%{opacity:.3}}
@keyframes pop{to{opacity:1;transform:translate(-50%,-50%) scale(1) rotate(var(--rot))}}
@keyframes beat{0%,100%{transform:scale(1)}15%{transform:scale(1.06)}30%{transform:scale(.98)}45%{transform:scale(1.04)}}
@keyframes spin{to{transform:rotate(360deg)}}
@keyframes rise{
  0%{transform:translate(0,0) scale(.4);opacity:1}
  100%{transform:translate(var(--dx),-70vh) scale(1.3) rotate(var(--r));opacity:0}
}
@keyframes fall{
  0%{transform:translate(0,0) rotate(0)}
  100%{transform:translate(var(--dx),calc(100vh + 260px)) rotate(var(--r))}
}
@media (prefers-reduced-motion:reduce){
  #openBtn,#intro h1,#heart.beat .inner{animation:none}
}