:root {
  --midnight: oklch(0.19 0.045 255);
  --deep-blue: oklch(0.27 0.065 246);
  --mist-violet: oklch(0.34 0.055 285);
  --paper: oklch(0.965 0.012 235 / 0.95);
  --paper-edge: oklch(0.84 0.022 239 / 0.46);
  --ink: oklch(0.245 0.035 250);
  --muted: oklch(0.49 0.035 247);
  --moon: oklch(0.91 0.022 238);
}

* { box-sizing: border-box; }

html {
  min-height: 100%;
  scroll-behavior: smooth;
  background: var(--midnight);
}

body {
  min-height: 100%;
  margin: 0;
  color: var(--ink);
  background: var(--midnight);
  font-family: "Songti SC", "STSong", "Noto Serif CJK SC", "SimSun", serif;
  overflow-x: hidden;
}

a { color: inherit; }

.tide-sky {
  position: fixed;
  inset: 0;
  z-index: 0;
  overflow: hidden;
  pointer-events: none;
  background:
    radial-gradient(ellipse at 13% 7%, oklch(0.78 0.035 246 / 0.12), transparent 27%),
    linear-gradient(171deg, var(--midnight) 0%, var(--deep-blue) 59%, var(--mist-violet) 100%);
}

.tide-sky::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 72% 18%, oklch(0.92 0.014 240 / 0.05) 0 1px, transparent 1.5px),
    radial-gradient(circle at 31% 32%, oklch(0.90 0.018 245 / 0.04) 0 1px, transparent 1.5px),
    radial-gradient(circle at 83% 43%, oklch(0.90 0.018 245 / 0.035) 0 1px, transparent 1.5px);
  background-size: 173px 191px, 239px 227px, 307px 293px;
  opacity: 0.65;
}

.tide-sky::after {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at center, transparent 38%, oklch(0.08 0.025 255 / 0.44) 100%);
}

.moon-haze {
  position: absolute;
  top: -11svh;
  left: -20vw;
  width: min(92vw, 760px);
  aspect-ratio: 1;
  border-radius: 50%;
  background: radial-gradient(circle, oklch(0.91 0.023 239 / 0.20), oklch(0.77 0.04 251 / 0.07) 34%, transparent 70%);
  filter: blur(22px);
}

.distant-shore {
  position: absolute;
  right: -8%;
  bottom: 19svh;
  left: -8%;
  height: 18svh;
  background: linear-gradient(180deg, transparent, oklch(0.13 0.038 254 / 0.52));
  filter: blur(15px);
}

.water {
  position: absolute;
  right: -12%;
  bottom: -8svh;
  left: -12%;
  height: 38svh;
  transform-origin: center bottom;
}

.water-back {
  background:
    radial-gradient(ellipse at 23% 22%, oklch(0.77 0.035 235 / 0.11), transparent 22%),
    radial-gradient(ellipse at 76% 43%, oklch(0.68 0.045 265 / 0.12), transparent 25%),
    linear-gradient(178deg, oklch(0.28 0.06 247 / 0.26), oklch(0.11 0.035 255 / 0.72));
  filter: blur(10px);
}

.water-front {
  bottom: -19svh;
  height: 42svh;
  border-radius: 48% 52% 0 0 / 13% 15% 0 0;
  background:
    linear-gradient(173deg, transparent 0 24%, oklch(0.52 0.045 238 / 0.10) 25%, transparent 27% 39%, oklch(0.72 0.028 231 / 0.08) 40%, transparent 42%),
    oklch(0.105 0.032 255 / 0.84);
  filter: blur(7px);
}

.water-light {
  position: absolute;
  bottom: 9svh;
  height: 2px;
  border-radius: 50%;
  background: linear-gradient(90deg, transparent, oklch(0.91 0.018 230 / 0.34), transparent);
  filter: blur(1px);
  opacity: 0.74;
  animation: drift-light 21s ease-in-out infinite alternate;
}

.water-light-one { left: 8%; width: 46%; }
.water-light-two { right: 4%; bottom: 16svh; width: 31%; opacity: 0.42; animation-delay: -8s; }
.water-light-three { left: 38%; bottom: 4svh; width: 24%; opacity: 0.28; animation-delay: -14s; }

.tide-shell {
  position: relative;
  z-index: 1;
  width: min(100%, 920px);
  margin: 0 auto;
  padding: max(24px, env(safe-area-inset-top)) clamp(14px, 4vw, 38px) max(44px, env(safe-area-inset-bottom));
}

.quiet-nav {
  width: min(100%, 720px);
  min-height: 44px;
  margin: 0 auto clamp(28px, 7vw, 58px);
  display: flex;
  justify-content: space-between;
  gap: 24px;
  align-items: center;
  color: oklch(0.89 0.025 239 / 0.78);
  font-family: "PingFang SC", "Helvetica Neue", sans-serif;
  font-size: 0.74rem;
}

.quiet-nav a,
.page-ending a {
  text-decoration: none;
  border-bottom: 1px solid oklch(0.86 0.025 239 / 0.38);
}

.quiet-nav a:focus-visible,
.page-ending a:focus-visible {
  outline: 3px solid oklch(0.89 0.035 239 / 0.75);
  outline-offset: 5px;
}

.tide-letter {
  position: relative;
  width: min(100%, 720px);
  margin: 0 auto;
  padding: clamp(44px, 9vw, 80px) clamp(24px, 7vw, 62px) clamp(58px, 10vw, 92px);
  background-color: var(--paper);
  background-image: url("../../assets/paper-texture.png");
  background-size: 520px auto;
  border: 1px solid var(--paper-edge);
  border-radius: 9px;
  box-shadow: 0 8px 8px oklch(0.07 0.025 255 / 0.22);
  overflow: hidden;
}

.tide-letter::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(ellipse at 8% 1%, oklch(0.83 0.035 238 / 0.18), transparent 29%),
    linear-gradient(180deg, transparent 82%, oklch(0.78 0.035 242 / 0.08));
  mix-blend-mode: multiply;
}

.tide-letter::after {
  content: "";
  position: absolute;
  inset: 18px;
  border-top: 1px solid oklch(0.66 0.03 242 / 0.22);
  border-bottom: 1px solid oklch(0.66 0.03 242 / 0.22);
  pointer-events: none;
}

.letter-heading,
.letter-body { position: relative; z-index: 1; }

.letter-heading {
  margin-bottom: clamp(40px, 9vw, 66px);
  padding-bottom: clamp(28px, 6vw, 42px);
  border-bottom: 1px solid oklch(0.62 0.035 244 / 0.24);
}

.letter-heading p {
  margin: 0 0 14px;
  color: var(--muted);
  font-size: 0.91rem;
  line-height: 1.7;
}

.letter-heading h1 {
  max-width: 8em;
  margin: 0;
  color: oklch(0.29 0.055 252);
  font-size: clamp(2.35rem, 8vw, 4.25rem);
  line-height: 1.18;
  font-weight: 500;
  letter-spacing: -0.025em;
  text-wrap: balance;
}

.letter-body {
  max-width: 67ch;
  margin: 0 auto;
  font-size: clamp(1.03rem, 3.8vw, 1.16rem);
  line-height: 2.08;
  text-wrap: pretty;
}

.letter-body > p { margin: 0; }
.letter-body > p + p { margin-top: 1.06em; }

.letter-ending {
  position: relative;
  margin-top: clamp(54px, 10vw, 78px);
  padding: clamp(40px, 8vw, 58px) 0 clamp(38px, 8vw, 56px);
  border-top: 1px solid oklch(0.61 0.035 243 / 0.24);
  overflow: visible;
}

.letter-ending p {
  position: relative;
  z-index: 1;
  margin: 0;
}

.letter-ending p:first-child {
  margin-bottom: 1.1em;
  color: oklch(0.31 0.055 252);
  font-size: 1.15em;
}

.tear-mark {
  position: absolute;
  right: -4%;
  bottom: -19px;
  width: clamp(105px, 28vw, 170px);
  height: clamp(62px, 16vw, 96px);
  border-radius: 46% 54% 57% 43% / 43% 40% 60% 57%;
  background:
    radial-gradient(ellipse at 46% 44%, oklch(0.79 0.035 234 / 0.16), oklch(0.70 0.045 245 / 0.08) 48%, transparent 72%);
  filter: blur(2px);
  transform: rotate(-9deg);
  mix-blend-mode: multiply;
}

.page-ending {
  width: min(100%, 720px);
  min-height: 44px;
  margin: clamp(34px, 7vw, 58px) auto 0;
  display: flex;
  justify-content: center;
  align-items: center;
  color: oklch(0.89 0.025 239 / 0.78);
  font-size: 0.86rem;
}

@keyframes drift-light {
  from { transform: translate3d(-6px, 0, 0) scaleX(0.96); opacity: 0.46; }
  to { transform: translate3d(12px, -2px, 0) scaleX(1.04); opacity: 0.78; }
}

@media (max-width: 520px) {
  .quiet-nav { align-items: flex-start; }
  .quiet-nav span { max-width: 10em; text-align: right; }

  .tide-letter {
    border-radius: 6px;
    box-shadow: 0 6px 8px oklch(0.07 0.025 255 / 0.20);
  }

  .tide-letter::after { inset: 12px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .water-light { animation: none; }
}