:root {
  --rose-050: #fff7fa;
  --rose-100: #fde9f1;
  --rose-200: #f3cada;
  --rose-300: #e9adc5;
  --wine-700: #6f2440;
  --wine-800: #52172d;
  --cream-050: #fffaf2;
  --paper: #fffaf5;
  --text: #4f1730;
  --shadow-soft: 0 16px 30px rgba(90, 24, 45, 0.18);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
}

body {
  font-family: "Palatino Linotype", "Book Antiqua", Palatino, serif;
  color: var(--text);
  background:
    radial-gradient(70rem 36rem at 14% -8%, rgba(255, 255, 255, 0.75), transparent 62%),
    radial-gradient(45rem 24rem at 92% 8%, rgba(216, 122, 151, 0.16), transparent 70%),
    linear-gradient(155deg, #fff9f6 0%, #ffeef4 46%, #f9e0ea 100%);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  text-size-adjust: 100%;
  -webkit-tap-highlight-color: transparent;
}

.bg-glow {
  position: fixed;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(circle at 18% 18%, rgba(255, 255, 255, 0.3), transparent 36%),
    radial-gradient(circle at 86% 84%, rgba(104, 25, 52, 0.08), transparent 32%);
}

.particles {
  position: fixed;
  inset: 0;
  pointer-events: none;
  overflow: hidden;
  contain: strict;
}

.heart {
  position: absolute;
  bottom: -10vh;
  width: var(--size);
  height: var(--size);
  background: rgba(212, 93, 128, 0.2);
  transform: rotate(45deg);
  border-radius: 2px;
  animation: heart-float var(--duration) linear infinite;
  animation-delay: var(--delay);
}

.heart::before,
.heart::after {
  content: "";
  position: absolute;
  width: 100%;
  height: 100%;
  border-radius: 50%;
  background: inherit;
}

.heart::before {
  left: -50%;
}

.heart::after {
  top: -50%;
}

@keyframes heart-float {
  0% {
    transform: translate3d(0, 0, 0) rotate(45deg) scale(0.75);
    opacity: 0;
  }
  16% {
    opacity: var(--opacity);
  }
  100% {
    transform: translate3d(var(--drift), -110vh, 0) rotate(45deg) scale(1.2);
    opacity: 0;
  }
}

.app {
  position: relative;
  z-index: 2;
  min-height: 100svh;
  display: grid;
  align-content: center;
  justify-items: center;
  gap: 0.95rem;
  padding: 1rem 0.9rem 1.1rem;
}

.hero {
  text-align: center;
}

.hero h1 {
  margin: 0;
  color: var(--wine-700);
  font-family: "Segoe Script", "Lucida Handwriting", "Brush Script MT", cursive;
  font-weight: 400;
  font-size: clamp(2rem, 10.8vw, 3.6rem);
  text-shadow: 0 10px 24px rgba(111, 36, 64, 0.18);
}

.hero p {
  margin: 0.15rem 0 0;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-size: clamp(0.7rem, 3.4vw, 0.95rem);
  color: rgba(82, 23, 45, 0.72);
}

.experience {
  width: min(27rem, 100%);
  text-align: center;
}

.stage {
  position: relative;
  width: min(92vw, 26rem);
  aspect-ratio: 1.15 / 1;
  margin-inline: auto;
  perspective: 1600px;
}

.envelope-trigger {
  position: absolute;
  inset: 0;
  z-index: 10;
  border: 0;
  background: transparent;
  cursor: pointer;
}

.stage.is-open .envelope-trigger {
  pointer-events: none;
}

.envelope {
  position: absolute;
  left: 50%;
  bottom: 0;
  width: 100%;
  height: 74%;
  transform: translateX(-50%);
  filter: drop-shadow(var(--shadow-soft));
}

.env-back,
.env-front,
.env-flap {
  position: absolute;
  inset: 0;
  border-radius: 1rem;
}

.env-back {
  background: linear-gradient(150deg, #f9dfeb 0%, #efbfd2 100%);
  overflow: hidden;
}

.env-back::before,
.env-back::after {
  content: "";
  position: absolute;
  inset: 0;
}

.env-back::before {
  clip-path: polygon(0 0, 50% 58%, 0 100%);
  background: linear-gradient(150deg, #efbdd0, #e39db9);
}

.env-back::after {
  clip-path: polygon(100% 0, 50% 58%, 100% 100%);
  background: linear-gradient(205deg, #efbdd0, #e39db9);
}

.env-front {
  height: 82%;
  bottom: 0;
  border-radius: 0 0 1rem 1rem;
  clip-path: polygon(0 0, 50% 58%, 100% 0, 100% 100%, 0 100%);
  background: linear-gradient(165deg, #f8e6ee 0%, #efbfd2 100%);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.65);
  z-index: 4;
}

.env-flap {
  height: 66%;
  top: 0;
  clip-path: polygon(0 0, 50% 100%, 100% 0);
  background: linear-gradient(180deg, #faecf3, #edb9cc);
  transform-origin: top center;
  transition: transform 760ms cubic-bezier(0.2, 0.75, 0.28, 1.04);
  z-index: 5;
  backface-visibility: hidden;
}

.env-flap::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 48%;
  width: 2.75rem;
  height: 2.75rem;
  transform: translate(-50%, -50%);
  border-radius: 50%;
  background: radial-gradient(circle at 34% 30%, #fff6fb 0 22%, #d8688f 60%, #a13d61 100%);
  box-shadow:
    0 6px 14px rgba(118, 27, 54, 0.33),
    inset 0 2px 2px rgba(255, 255, 255, 0.45);
}

.stage.is-open .env-flap {
  transform: rotateX(178deg);
}

.letter {
  position: absolute;
  left: 50%;
  bottom: 0.7rem;
  width: 88%;
  height: 78%;
  max-height: 19rem;
  transform: translate(-50%, 60%) scale(0.99);
  opacity: 0;
  border-radius: 0.95rem;
  background: linear-gradient(180deg, #fffdf9 0%, var(--paper) 100%);
  box-shadow:
    0 14px 26px rgba(86, 21, 42, 0.22),
    0 3px 0 #f1dfd0,
    inset 0 0 0 1px rgba(183, 130, 113, 0.24);
  transition:
    transform 920ms cubic-bezier(0.19, 0.85, 0.25, 1.03),
    opacity 480ms ease;
  overflow: hidden;
  z-index: 3;
}

.letter::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    repeating-linear-gradient(
      0deg,
      rgba(153, 118, 100, 0.05) 0,
      rgba(153, 118, 100, 0.05) 1px,
      transparent 1px,
      transparent 5px
    );
  pointer-events: none;
}

.stage.is-open .letter {
  opacity: 1;
  transform: translate(-50%, -39%) scale(1);
  transition-delay: 120ms;
}

.letter-content {
  position: relative;
  z-index: 1;
  height: 100%;
  overflow: auto;
  text-align: left;
  padding: 1rem 0.95rem 1.15rem;
  opacity: 0;
  transform: translateY(0.65rem);
  transition: opacity 520ms ease, transform 520ms ease;
}

.stage.show-message .letter-content {
  opacity: 1;
  transform: translateY(0);
}

.letter-content h2 {
  margin: 0 0 0.5rem;
  color: var(--wine-700);
  font-size: clamp(1.08rem, 5.3vw, 1.2rem);
}

.letter-content p {
  margin: 0 0 0.62rem;
  color: var(--wine-800);
  line-height: 1.45;
  font-size: clamp(0.9rem, 3.9vw, 1rem);
}

.letter-content p:last-child {
  margin-bottom: 0;
}

.letter-content::-webkit-scrollbar {
  width: 0.48rem;
}

.letter-content::-webkit-scrollbar-thumb {
  background: rgba(140, 67, 95, 0.28);
  border-radius: 100px;
}

.hint {
  margin: 0.65rem 0 0;
  color: rgba(82, 23, 45, 0.72);
  font-size: clamp(0.76rem, 3.5vw, 0.94rem);
}

.controls {
  margin-top: 0.75rem;
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 0.58rem;
  flex-wrap: wrap;
}

.btn {
  min-height: 2.75rem;
  min-width: 9.2rem;
  border: 1px solid rgba(122, 45, 71, 0.28);
  border-radius: 999px;
  background: rgba(255, 250, 246, 0.84);
  color: #67213b;
  padding: 0.58rem 1rem;
  font: 600 0.9rem/1 "Trebuchet MS", "Segoe UI", sans-serif;
  letter-spacing: 0.02em;
  cursor: pointer;
  touch-action: manipulation;
  transition: transform 200ms ease, box-shadow 200ms ease, background 200ms ease;
}

.btn:hover {
  background: rgba(255, 247, 241, 0.96);
  transform: translateY(-1px);
  box-shadow: 0 8px 14px rgba(106, 36, 58, 0.16);
}

.btn:active {
  transform: translateY(0);
}

.btn:focus-visible {
  outline: 2px solid rgba(111, 36, 64, 0.5);
  outline-offset: 2px;
}

.btn[disabled] {
  opacity: 0.5;
  cursor: not-allowed;
  box-shadow: none;
}

.btn-secondary {
  background: rgba(255, 248, 240, 0.72);
}

@media (min-width: 700px) {
  .app {
    gap: 1.15rem;
    padding-top: 1.4rem;
  }

  .experience {
    width: min(30rem, 100%);
  }

  .stage {
    width: min(84vw, 28rem);
  }
}

@media (max-width: 430px) {
  body {
    background: linear-gradient(155deg, #fff9f6 0%, #ffeef4 46%, #f9e0ea 100%);
  }

  .bg-glow {
    display: none;
  }

  .envelope {
    filter: drop-shadow(0 10px 20px rgba(90, 24, 45, 0.16));
  }

  .letter {
    box-shadow:
      0 10px 18px rgba(86, 21, 42, 0.16),
      0 2px 0 #f1dfd0,
      inset 0 0 0 1px rgba(183, 130, 113, 0.24);
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation: none !important;
    transition-duration: 0.01ms !important;
    transition-delay: 0ms !important;
  }
}