:root {
  color-scheme: light dark;
  --page: #dce5df;
  --page-deep: #c5d3ca;
  --ink: #24332d;
  --muted: #596b63;
  --paper: #fffdf7;
  --paper-shadow: rgba(55, 76, 65, 0.2);
  --accent: #9a4f5c;
  --accent-deep: #733742;
  --line: rgba(75, 98, 86, 0.22);
  --envelope: #f0c8cb;
  --envelope-deep: #dca8ad;
  --focus: #2e6851;
  --radius: 6px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-width: 320px;
  background:
    radial-gradient(circle at 15% 10%, rgba(255, 255, 255, 0.46), transparent 28rem),
    linear-gradient(145deg, var(--page), var(--page-deep));
  color: var(--ink);
  font-family: "Avenir Next", Avenir, "Segoe UI", system-ui, sans-serif;
}

button {
  font: inherit;
}

button:focus-visible,
.letter-stage:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 5px;
}

.page-shell {
  min-height: 100dvh;
  padding: clamp(2rem, 7vw, 5rem) 1rem;
}

.intro {
  display: grid;
  justify-items: center;
  width: min(100%, 62rem);
  min-height: calc(100dvh - clamp(4rem, 14vw, 10rem));
  margin: 0 auto;
  align-content: center;
  text-align: center;
}

.intro[hidden] {
  display: none;
}

.occasion,
.letter-header p {
  margin: 0 0 0.75rem;
  color: var(--accent-deep);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

h1,
h2 {
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 500;
}

h1 {
  max-width: 12ch;
  margin: 0;
  font-size: clamp(3.25rem, 9vw, 6.8rem);
  line-height: 0.93;
  letter-spacing: -0.045em;
}

.intro-copy {
  max-width: 34rem;
  margin: 1.25rem 0 2.5rem;
  color: var(--muted);
  font-size: clamp(1rem, 2vw, 1.14rem);
  line-height: 1.6;
}

.envelope {
  position: relative;
  width: min(78vw, 27rem);
  aspect-ratio: 1.62;
  padding: 0;
  overflow: visible;
  border: 0;
  border-radius: var(--radius);
  background: var(--envelope);
  box-shadow: 0 24px 55px rgba(73, 91, 82, 0.22);
  color: var(--ink);
  cursor: pointer;
  transform: rotate(-1.5deg);
  transition: transform 260ms ease, box-shadow 260ms ease;
}

.envelope:hover {
  box-shadow: 0 30px 65px rgba(73, 91, 82, 0.29);
  transform: rotate(0deg) translateY(-5px);
}

.envelope:active {
  transform: rotate(0deg) translateY(-1px) scale(0.985);
}

.envelope-flap {
  position: absolute;
  inset: 0 0 auto;
  height: 62%;
  border-radius: var(--radius) var(--radius) 0 0;
  background: var(--envelope-deep);
  clip-path: polygon(0 0, 100% 0, 50% 88%);
  transform-origin: top;
  transition: transform 700ms cubic-bezier(0.2, 0.75, 0.25, 1);
}

.envelope-pocket {
  position: absolute;
  inset: 0;
  border-radius: var(--radius);
  background:
    linear-gradient(32deg, var(--envelope) 49.4%, transparent 50%) left bottom / 51% 100% no-repeat,
    linear-gradient(-32deg, var(--envelope) 49.4%, transparent 50%) right bottom / 51% 100% no-repeat;
}

.envelope-address {
  position: absolute;
  inset: 39% 20% auto;
  display: grid;
  gap: 0.2rem;
  place-items: center;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(1.45rem, 4.5vw, 2rem);
  font-style: italic;
}

.envelope-address small {
  font-family: "Avenir Next", Avenir, "Segoe UI", system-ui, sans-serif;
  font-size: 0.7rem;
  font-style: normal;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.wax-seal {
  position: absolute;
  left: 50%;
  top: 56%;
  display: grid;
  width: 3.1rem;
  aspect-ratio: 1;
  place-items: center;
  border: 2px solid rgba(255, 242, 238, 0.28);
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 4px 12px rgba(90, 45, 54, 0.28), inset 0 0 0 3px var(--accent);
  color: #fff8f4;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.45rem;
  transform: translate(-50%, -50%);
}

.open-hint {
  margin: 1.4rem 0 0;
  color: var(--muted);
  font-size: 0.86rem;
}

.intro.is-opening .envelope-flap {
  transform: rotateX(175deg);
}

.intro.is-opening .envelope {
  transform: translateY(12px) scale(0.97);
}

.letter-stage {
  width: min(100%, 56rem);
  margin: 0 auto;
  scroll-margin-top: 1.5rem;
}

.letter-stage[hidden] {
  display: none;
}

.letter-paper {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  border: 1px solid rgba(86, 106, 95, 0.18);
  border-radius: var(--radius);
  background:
    linear-gradient(rgba(255, 255, 255, 0.24), rgba(255, 255, 255, 0.24)),
    repeating-linear-gradient(0deg, transparent 0 31px, rgba(108, 129, 116, 0.045) 31px 32px),
    var(--paper);
  box-shadow: 0 32px 90px var(--paper-shadow);
  padding: clamp(3rem, 8vw, 6.5rem) clamp(1.45rem, 8vw, 6.5rem) clamp(2.5rem, 7vw, 5rem);
}

.botanical {
  position: absolute;
  z-index: -1;
  width: min(58%, 31rem);
  height: auto;
  pointer-events: none;
  user-select: none;
}

.botanical-top {
  top: -2rem;
  right: -5rem;
  opacity: 0.7;
  transform: rotate(2deg);
}

.letter-header {
  position: relative;
  max-width: 34rem;
  padding: 0 0 2rem;
  border-bottom: 1px solid var(--line);
}

.letter-header h2 {
  margin: 0;
  font-size: clamp(2.5rem, 6vw, 4.3rem);
  line-height: 1.05;
  letter-spacing: -0.035em;
}

.letter-body {
  max-width: 43rem;
  padding-top: 1.1rem;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(1.15rem, 2.2vw, 1.36rem);
  line-height: 1.74;
}

.letter-body p {
  margin: 1.35em 0 0;
}

.closing-wish {
  color: var(--accent-deep);
  font-size: 1.12em;
  font-weight: 500;
}

.signature {
  display: grid;
  width: max-content;
  margin: 2.4rem 0 0 auto;
  color: var(--accent-deep);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.15rem;
}

.signature strong {
  margin-top: 0.15rem;
  font-size: 2.6rem;
  font-style: italic;
  font-weight: 500;
  line-height: 1.1;
}

.letter-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem 1.2rem;
  align-items: center;
  margin-top: 3.25rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--line);
}

.text-button {
  min-height: 3rem;
  border-radius: var(--radius);
  cursor: pointer;
  font-weight: 600;
  white-space: nowrap;
  transition: transform 160ms ease, background-color 160ms ease;
}

.text-button {
  border: 0;
  background: transparent;
  color: var(--accent-deep);
  padding: 0.75rem 0.3rem;
  text-decoration: underline;
  text-underline-offset: 0.25em;
}

.text-button:active {
  transform: translateY(1px);
}

@media (prefers-color-scheme: dark) {
  :root {
    --page: #1e2a25;
    --page-deep: #111b17;
    --ink: #28372f;
    --muted: #c5d2cb;
    --paper: #f3eee4;
    --paper-shadow: rgba(0, 0, 0, 0.42);
    --line: rgba(62, 82, 71, 0.24);
    --focus: #b9ddca;
  }

  .intro {
    color: #edf3ef;
  }

  .occasion,
  .intro .open-hint {
    color: #dcb9be;
  }
}

@media (max-width: 600px) {
  .page-shell {
    padding: 1.5rem 0.75rem 2.5rem;
  }

  .intro {
    min-height: calc(100dvh - 4rem);
  }

  h1 {
    font-size: clamp(3.1rem, 16vw, 4.7rem);
  }

  .intro-copy {
    max-width: 27ch;
    margin-bottom: 2rem;
  }

  .letter-paper {
    padding-inline: clamp(1.3rem, 6vw, 2rem);
  }

  .botanical-top {
    top: -1rem;
    right: -4.5rem;
    width: 78%;
    opacity: 0.48;
  }

  .letter-header {
    padding-top: 2.5rem;
  }

  .letter-body {
    font-size: 1.15rem;
    line-height: 1.68;
  }

  .letter-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .text-button {
    width: 100%;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}