/* 首屏、信封、信纸——开场到的第一段路。 */
.hero {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start;
  text-align: center;
  min-height: 100vh;
  min-height: 100svh;
  padding: clamp(3rem, 11vh, 7rem) var(--gutter, 1.5rem) clamp(2rem, 6vh, 4rem);
}

.hero::before {
  content: "";
  position: absolute;
  top: clamp(0.5rem, 4vh, 3rem);
  left: 50%;
  z-index: -1;
  width: min(48rem, 132vw);
  aspect-ratio: 3 / 2;
  transform: translateX(-50%);
  background-image: radial-gradient(50% 50% at 50% 50%, rgba(255, 246, 233, 0.92), rgba(255, 246, 233, 0) 71%);
  animation: hero-halo 11s ease-in-out infinite;
  pointer-events: none;
}

@keyframes hero-halo {
  0%, 100% { opacity: 0.62; transform: translateX(-50%) scale(1); }
  50% { opacity: 0.92; transform: translateX(-50%) scale(1.035); }
}

.hero__eyebrow {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  font-size: 0.68rem;
  letter-spacing: 0.34em;
  color: var(--ink-soft, #5b6b80);
  text-indent: 0.34em;
}

.hero__dot {
  width: 3px;
  height: 3px;
  border-radius: 50%;
  background: var(--blush, #f3b8c0);
}

.hero__title {
  margin-top: clamp(1.1rem, 3vh, 1.8rem);
  font-family: var(--font-display, serif);
  font-size: clamp(2.35rem, 6vw, 4.8rem);
  font-weight: 500;
  line-height: 1.12;
  letter-spacing: 0.07em;
  color: var(--ink, #2e3b4e);
  text-shadow: 0 1px 0 rgba(255, 255, 255, 0.65);
}

.hero__title-line {
  display: block;
}

.hero__title-line--tail {
  font-size: 0.76em;
  letter-spacing: 0.22em;
  color: rgba(46, 59, 78, 0.88);
}

.hero__title-line--tail::before {
  content: "";
  display: inline-block;
  width: clamp(1.2rem, 4.5vw, 2.4rem);
  height: 1px;
  margin-right: 0.5em;
  vertical-align: 0.34em;
  background-image: linear-gradient(90deg, rgba(238, 186, 150, 0), rgba(238, 186, 150, 0.95));
}

.hero__sub {
  margin-top: clamp(0.95rem, 2.4vh, 1.5rem);
  max-width: min(31rem, 100%);
  font-size: clamp(0.92rem, 0.88rem + 0.24vw, 1.06rem);
  line-height: 1.9;
  letter-spacing: 0.07em;
  color: var(--ink-soft, #5b6b80);
}

.hero__sub-br {
  display: none;
}

.hero__actions {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.1rem;
  margin-top: clamp(1.9rem, 5vh, 2.9rem);
}

.pill {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.92rem 2.05rem;
  border: 0;
  border-radius: var(--radius-pill, 999px);
  font-size: 0.96rem;
  letter-spacing: 0.14em;
  text-indent: 0.14em;
  color: var(--ink, #2e3b4e);
  background-image: linear-gradient(135deg, #fbd8b8 0%, #f7c9a8 46%, #f1b5bc 100%);
  box-shadow:
    0 18px 32px -20px rgba(203, 122, 112, 0.95),
    inset 0 1px 0 rgba(255, 255, 255, 0.6);
  cursor: pointer;
  overflow: hidden;
  -webkit-tap-highlight-color: transparent;
  transition:
    transform var(--dur-1, 220ms) var(--ease-out, ease-out),
    box-shadow var(--dur-1, 220ms) var(--ease-out, ease-out);
}

.pill::after {
  content: "";
  position: absolute;
  inset: -40% -10%;
  background: radial-gradient(60% 80% at 30% 0%, rgba(255, 255, 255, 0.85), rgba(255, 255, 255, 0) 70%);
  opacity: 0;
  transition: opacity var(--dur-2, 520ms) var(--ease-out, ease-out);
  pointer-events: none;
}

.pill:hover {
  transform: translateY(-2px);
  box-shadow:
    0 22px 36px -20px rgba(203, 122, 112, 0.95),
    inset 0 1px 0 rgba(255, 255, 255, 0.7);
}

.pill:hover::after {
  opacity: 1;
}

.pill:active {
  transform: translateY(0) scale(0.986);
}

.pill__icon {
  width: 1.05em;
  height: 1.05em;
  opacity: 0.72;
}

.hero__badge {
  display: inline-flex;
  align-items: baseline;
  gap: 0.3rem;
  padding: 0.32rem 0.95rem;
  border: 1px solid rgba(46, 59, 78, 0.09);
  border-radius: var(--radius-pill, 999px);
  font-size: 0.7rem;
  letter-spacing: 0.2em;
  color: var(--ink-soft, #5b6b80);
  background: rgba(255, 255, 255, 0.5);
}

.hero__badge b {
  font-family: var(--font-display, serif);
  font-size: 0.94rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  color: var(--ink, #2e3b4e);
}

.hero__cue {
  position: relative;
  display: block;
  width: 1px;
  height: clamp(26px, 4.6vh, 38px);
  margin-top: auto;
  background: linear-gradient(180deg, rgba(46, 59, 78, 0), rgba(46, 59, 78, 0.42));
  opacity: 0.58;
  animation: cue-breathe 3.6s ease-in-out infinite;
}

.hero__cue::after {
  content: "";
  position: absolute;
  top: 100%;
  left: 50%;
  width: 7px;
  height: 7px;
  margin: -5px 0 0 -4px;
  border-right: 1px solid rgba(46, 59, 78, 0.55);
  border-bottom: 1px solid rgba(46, 59, 78, 0.55);
  transform: rotate(45deg);
}

.hero__cue i {
  position: absolute;
  top: 0;
  left: 50%;
  width: 4px;
  height: 4px;
  margin-left: -2px;
  border-radius: 50%;
  background: var(--blush, #f3b8c0);
  animation: cue-drift 2.8s var(--ease-out, ease-out) infinite;
}

@keyframes cue-drift {
  0% { transform: translateY(0); opacity: 0; }
  25% { opacity: 0.95; }
  100% { transform: translateY(clamp(26px, 4.6vh, 38px)); opacity: 0; }
}

@keyframes cue-breathe {
  0%, 100% { opacity: 0.38; }
  50% { opacity: 0.68; }
}

/* ── 信封与信纸共用的舞台 ── */
.stage {
  padding: clamp(1.5rem, 5vh, 3.5rem) var(--gutter, 1.5rem) clamp(2.5rem, 8vh, 5rem);
  scroll-margin-top: 10vh;
}

.stage__inner {
  position: relative;
  display: grid;
  grid-template-columns: 1fr;
  justify-items: center;
  width: 100%;
  max-width: var(--stage-max, 46rem);
  margin-inline: auto;
}

.envelope-wrap {
  grid-area: 1 / 1;
  align-self: start;
  justify-self: center;
  display: grid;
  justify-items: center;
  gap: clamp(1rem, 3vh, 1.7rem);
  padding-block: clamp(1rem, 4vh, 2.5rem);
  transition:
    opacity var(--dur-2, 520ms) var(--ease-out, ease-out) 0.42s,
    transform 0.8s var(--ease-out, ease-out) 0.42s,
    visibility 0s linear 0s;
}

html.is-opened .envelope-wrap {
  opacity: 0;
  transform: translateY(-16px) scale(0.94);
  visibility: hidden;
  pointer-events: none;
  transition:
    opacity 0.46s var(--ease-out, ease-out) 0.4s,
    transform 0.8s var(--ease-out, ease-out) 0.4s,
    visibility 0s linear 1.15s;
}

.envelope {
  position: relative;
  width: min(21rem, 76vw);
  aspect-ratio: 1.52 / 1;
  padding: 0;
  border: 0;
  background: none;
  cursor: pointer;
  perspective: 900px;
  filter: drop-shadow(0 18px 22px -18px rgba(46, 59, 78, 0.5));
  transition: transform var(--dur-2, 520ms) var(--ease-out, ease-out);
  -webkit-tap-highlight-color: transparent;
}

.envelope::before {
  content: "";
  position: absolute;
  inset: -14% -12%;
  border-radius: 50%;
  background: radial-gradient(50% 50% at 50% 46%, rgba(255, 246, 233, 0.95), rgba(255, 246, 233, 0) 72%);
  opacity: 0.55;
  animation: envelope-glow 6.5s ease-in-out infinite;
  pointer-events: none;
}

@keyframes envelope-glow {
  0%, 100% { opacity: 0.5; }
  50% { opacity: 0.88; }
}

.envelope:hover {
  transform: translateY(-4px);
}

.envelope__back,
.envelope__front,
.envelope__flap {
  position: absolute;
  inset: 0;
  border-radius: 0.35rem;
}

.envelope__back {
  inset: 0 -1.4% -2.4% -1.4%;
  border-radius: 0.42rem;
  background-image: linear-gradient(180deg, #efe2c9 0%, #e9dac0 60%, #dfcdae 100%);
  box-shadow:
    var(--shadow-soft, 0 18px 40px -24px rgba(46, 59, 78, 0.45)),
    inset 0 0 0 1px rgba(46, 59, 78, 0.12);
}

.envelope__front {
  clip-path: polygon(0 0, 50% 52%, 100% 0, 100% 100%, 0 100%);
  background-image: linear-gradient(180deg, #f9f2e1 0%, #f6edda 40%, #efe3cc 100%);
  box-shadow: inset 0 0 0 1px rgba(46, 59, 78, 0.07);
  z-index: 3;
}

.envelope__flap {
  clip-path: polygon(0 0, 100% 0, 50% 52%);
  background-image: linear-gradient(180deg, #fffdf7 0%, #fbf5e6 62%, #f3e8d1 100%);
  filter: drop-shadow(0 1px 1px rgba(46, 59, 78, 0.22));
  transform-origin: top center;
  transform: rotateX(0deg);
  z-index: 4;
  transition:
    transform 0.78s var(--ease-out, ease-out) 0.16s,
    opacity 0.32s ease-out 0.62s;
}

html.is-opened .envelope__flap {
  transform: rotateX(-172deg);
  opacity: 0;
}

.envelope__flap::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(180deg, rgba(255, 255, 255, 0.72) 0%, rgba(255, 255, 255, 0) 52%),
    linear-gradient(180deg, rgba(226, 199, 160, 0) 74%, rgba(214, 186, 148, 0.3) 100%);
  pointer-events: none;
}

.envelope__postmark {
  position: absolute;
  right: 8%;
  bottom: 9%;
  z-index: 5;
  display: grid;
  place-items: center;
  width: clamp(2.9rem, 12vw, 3.5rem);
  aspect-ratio: 1;
  border: 1px dashed rgba(46, 59, 78, 0.3);
  border-radius: 50%;
  transform: rotate(-9deg);
  color: rgba(46, 59, 78, 0.62);
  opacity: 0.62;
  font-family: var(--font-body, system-ui);
  font-size: 0.44rem;
  line-height: 1.5;
  letter-spacing: 0.04em;
  pointer-events: none;
}

.envelope__postmark em,
.envelope__postmark b {
  display: block;
  font-style: normal;
  font-weight: 400;
}

.seal {
  position: absolute;
  left: 50%;
  top: 52%;
  width: clamp(3.4rem, 14vw, 4.4rem);
  aspect-ratio: 1;
  transform: translate(-50%, -50%);
  z-index: 6;
}

.seal__half {
  position: absolute;
  inset: 0;
  transition:
    transform 0.44s var(--ease-out, ease-out),
    opacity 0.4s ease-out 0.1s;
}

.seal__half--l {
  clip-path: polygon(0 0, 54% 0, 46% 100%, 0 100%);
}

.seal__half--r {
  clip-path: polygon(54% 0, 100% 0, 100% 100%, 46% 100%);
}

.seal__face {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  border-radius: 48% 52% 47% 53% / 52% 48% 53% 47%;
  line-height: 1;
  color: #fff8ef;
  text-shadow: 0 1px 1px rgba(140, 70, 70, 0.45);
  background-image: radial-gradient(circle at 34% 26%, #fbd0c6 0%, #f2b6ab 42%, #e5a09c 74%, #d68d8d 100%);
  box-shadow:
    inset 0 0 0 2px rgba(255, 255, 255, 0.34),
    inset 0 0 0 7px rgba(255, 255, 255, 0.13),
    inset 0 -7px 12px -7px rgba(120, 60, 60, 0.55),
    0 6px 10px -6px rgba(120, 60, 60, 0.5);
}

.seal__plane {
  width: 54%;
  height: 54%;
  color: #fff8ef;
  filter: drop-shadow(0 1px 0.5px rgba(140, 70, 70, 0.5));
  transform: rotate(-6deg);
}

html.is-opened .seal__half--l {
  transform: translate(-15%, -7%) rotate(-15deg);
  opacity: 0;
}

html.is-opened .seal__half--r {
  transform: translate(15%, 9%) rotate(13deg);
  opacity: 0;
}

.stage__hint {
  font-size: 0.71rem;
  letter-spacing: 0.24em;
  text-indent: 0.24em;
  color: var(--ink-soft, #5b6b80);
  opacity: 0.74;
}

/* ── 信纸 ── */
body.has-paper #paper .paper__inner {
  background-image:
    linear-gradient(rgba(254, 252, 246, 0.82), rgba(248, 242, 231, 0.82)),
    var(--paper-url, none);
  background-size: auto, cover;
  background-position: center;
}

.paper {
  grid-area: 1 / 1;
  align-self: start;
  justify-self: center;
  position: relative;
  width: 100%;
  min-width: 0;
  opacity: 1;
  transform: translateY(0) scale(1);
  transition:
    opacity var(--dur-2, 520ms) var(--ease-out, ease-out) 0.5s,
    transform var(--dur-3, 1200ms) var(--ease-out, ease-out) 0.44s,
    visibility 0s linear 0s;
}

html:not(.is-opened) .paper {
  position: absolute;
  inset: 0 0 auto;
  height: 0;
  overflow: hidden;
  opacity: 0;
  visibility: hidden;
  transform: translateY(26px) scale(0.975);
  transition:
    opacity 0.3s ease-out,
    transform 0.3s ease-out,
    visibility 0s linear 0.3s;
}

.paper__inner {
  position: relative;
  isolation: isolate;
  padding: clamp(1.7rem, 5vw, 3.4rem) clamp(1.4rem, 5.4vw, 3.4rem) clamp(1.7rem, 5vw, 3rem);
  border-radius: var(--radius-lg, 28px);
  background-image: linear-gradient(180deg, #fefcf6 0%, var(--paper, #fbf8f1) 42%, #f8f2e7 100%);
  box-shadow:
    var(--shadow-soft, 0 18px 40px -24px rgba(46, 59, 78, 0.45)),
    inset 0 0 0 1px rgba(46, 59, 78, 0.05);
}

.paper__inner::before {
  content: "";
  position: absolute;
  inset: 0.62rem;
  border: 1px solid rgba(226, 199, 160, 0.42);
  border-radius: calc(var(--radius-lg, 28px) - 12px);
  pointer-events: none;
}

/* 纸纤维 + 左侧装订线，压在正文之下 */
.paper__inner::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  border-radius: inherit;
  pointer-events: none;
  background-image:
    linear-gradient(
      90deg,
      transparent calc(clamp(1.4rem, 5.4vw, 3.4rem) - 1px),
      rgba(226, 199, 160, 0.5) calc(clamp(1.4rem, 5.4vw, 3.4rem) - 1px),
      rgba(226, 199, 160, 0.5) clamp(1.4rem, 5.4vw, 3.4rem),
      transparent clamp(1.4rem, 5.4vw, 3.4rem)
    ),
    repeating-linear-gradient(
      94deg,
      rgba(226, 199, 160, 0.1) 0 1px,
      transparent 1px 3px,
      rgba(255, 255, 255, 0.5) 3px 4px,
      transparent 4px 7px
    ),
    repeating-linear-gradient(
      2deg,
      rgba(46, 59, 78, 0.018) 0 1px,
      transparent 1px 5px
    );
  opacity: 0.85;
}

.paper__inner {
  border-radius: 30px 26px 28px 24px;
}

.paper::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: 0;
  width: clamp(1.7rem, 5.6vw, 2.5rem);
  height: clamp(1.7rem, 5.6vw, 2.5rem);
  border-bottom-right-radius: 24px;
  background-image: linear-gradient(
    135deg,
    rgba(46, 59, 78, 0) 44%,
    rgba(46, 59, 78, 0.05) 52%,
    rgba(255, 255, 255, 0.92) 72%,
    #efe5d4 100%
  );
  pointer-events: none;
  transition: opacity var(--dur-2, 520ms) var(--ease-out, ease-out) 0.7s;
}

html:not(.is-opened) .paper::after {
  opacity: 0;
}

.paper__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
}

.paper__to {
  font-family: var(--font-display, serif);
  font-size: 0.82rem;
  letter-spacing: 0.16em;
  color: var(--ink-soft, #5b6b80);
}

.paper__to b {
  margin-left: 0.4rem;
  font-size: 1.04rem;
  font-weight: 500;
  letter-spacing: 0.14em;
  color: var(--ink, #2e3b4e);
}

.paper__date {
  font-size: 0.7rem;
  letter-spacing: 0.18em;
  color: var(--ink-soft, #5b6b80);
}

.paper__rule {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin: 0.95rem 0 clamp(1.1rem, 3vw, 1.7rem);
  color: rgba(238, 186, 150, 0.95);
}

.paper__rule i {
  flex: 1;
  height: 1px;
  background-image: linear-gradient(90deg, rgba(226, 199, 160, 0), rgba(226, 199, 160, 0.9), rgba(226, 199, 160, 0));
}

.paper__rule svg {
  width: 1rem;
  height: 1rem;
  flex: none;
}

.paper__body {
  font-family: var(--font-display, serif);
  color: var(--ink, #2e3b4e);
}

.letter-p {
  margin: 0 0 1.1em;
  font-size: clamp(1rem, 0.95rem + 0.2vw, 1.08rem);
  line-height: 2;
  letter-spacing: 0.02em;
  text-indent: 2em;
  overflow-wrap: break-word;
  opacity: 0;
  transform: translateY(14px);
  transition:
    opacity 0.62s var(--ease-out, ease-out) calc(0.9s + var(--i, 0) * 60ms),
    transform 0.62s var(--ease-out, ease-out) calc(0.9s + var(--i, 0) * 60ms);
}

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

.kao {
  margin-inline-start: 0.08em;
  letter-spacing: 0.04em;
  white-space: nowrap;
}

html.is-opened .letter-p {
  opacity: 1;
  transform: none;
}

.letter-counter .lc-date,
.letter-counter .lc-time {
  white-space: nowrap;
}

.letter-counter {
  display: inline-block;
  white-space: nowrap;
  text-indent: 0;
  margin-inline-end: 0.1em;
  font-family: var(--font-body, system-ui);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.01em;
}

.letter-counter .lc-date {
  font-weight: 600;
}

.letter-counter .lc-time {
  font-weight: 300;
  color: var(--ink-soft, #5b6b80);
}

.letter-counter .lc-n {
  display: inline-block;
  min-width: 2ch;
  text-align: right;
}

@media (max-width: 340px) {
  .letter-counter {
    font-size: 0.9em;
  }
}

.paper__ps {
  margin-top: 1.3rem;
  padding-top: 1rem;
  border-top: 1px dashed rgba(46, 59, 78, 0.14);
  font-family: var(--font-display, serif);
  font-size: 0.95rem;
  line-height: 1.9;
  color: var(--ink-soft, #5b6b80);
}

.paper__foot {
  display: flex;
  align-items: baseline;
  justify-content: flex-end;
  gap: 0.5rem;
  margin-top: clamp(1.5rem, 4vw, 2.2rem);
  font-family: var(--font-display, serif);
}

.paper__from-label {
  font-size: 0.68rem;
  letter-spacing: 0.24em;
  color: var(--ink-soft, #5b6b80);
}

.paper__from {
  font-size: 1.02rem;
  font-weight: 500;
  letter-spacing: 0.3em;
}

/* 窄屏：整块淡入放大，不做 3D 翻折 */
@media (max-width: 600px) {
  .hero {
    min-height: auto;
    padding-block: clamp(2.8rem, 11vh, 4.4rem) clamp(1.6rem, 4vh, 2.6rem);
  }

  .hero__sub-br {
    display: block;
    height: 0;
    overflow: hidden;
  }

  .hero__cue {
    margin-top: clamp(1.4rem, 4vh, 2.2rem);
  }

  .envelope__flap {
    transition: opacity 0.4s ease-out 0.12s;
    transform: none;
  }

  html.is-opened .envelope__flap {
    transform: none;
    opacity: 0;
  }

  html.is-opened .seal__half--l {
    transform: translateY(-8%) rotate(-9deg);
  }

  html.is-opened .seal__half--r {
    transform: translateY(8%) rotate(8deg);
  }

  html:not(.is-opened) .paper {
    transform: scale(0.965);
  }

  .paper__inner::before {
    inset: 0.45rem;
  }
}