:root {
  --ink: #171513;
  --muted: #746b5d;
  --paper: #eadcc6;
  --paper-soft: #f7eedf;
  --panel: #fff8ed;
  --line: rgba(43, 31, 22, 0.16);
  --green: #234a25;
  --green-deep: #102714;
  --blue: #315c66;
  --gold: #d99b3d;
  color-scheme: light;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  margin: 0;
  background:
    linear-gradient(rgba(43, 31, 22, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(43, 31, 22, 0.04) 1px, transparent 1px),
    var(--paper);
  background-size: 56px 56px;
  color: var(--ink);
  font-family:
    ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "PingFang SC",
    "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  line-height: 1.72;
}

a {
  color: inherit;
}

.letter-nav {
  position: sticky;
  z-index: 10;
  top: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 14px clamp(18px, 4vw, 48px);
  background: rgba(234, 220, 198, 0.86);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(18px);
}

.letter-mark {
  display: grid;
  width: 40px;
  height: 40px;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 50%;
  background: var(--panel);
  color: var(--green-deep);
  font-weight: 950;
  text-decoration: none;
  box-shadow: 0 12px 30px rgba(36, 24, 16, 0.1);
}

.letter-nav nav {
  display: flex;
  gap: 6px;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 5px;
  background: rgba(255, 248, 237, 0.84);
}

.letter-nav nav a {
  border-radius: 999px;
  padding: 7px 12px;
  color: var(--ink);
  font-size: 12px;
  font-weight: 850;
  text-decoration: none;
}

.letter-nav nav a:hover {
  background: rgba(35, 74, 37, 0.12);
}

.letter-shell {
  width: min(100%, 1120px);
  margin: 0 auto;
  padding: clamp(38px, 6vw, 72px) clamp(20px, 5vw, 56px) 40px;
}

.letter-article {
  max-width: 760px;
  margin: 0 auto;
}

.letter-head {
  padding-bottom: clamp(28px, 4vw, 42px);
  border-bottom: 1px solid var(--line);
}

.back-link,
.kicker {
  color: var(--green);
  font-size: 11px;
  font-weight: 950;
  letter-spacing: 0;
  text-transform: uppercase;
}

.back-link {
  display: inline-flex;
  margin-bottom: 26px;
  text-decoration-thickness: 2px;
  text-underline-offset: 5px;
}

.kicker {
  margin: 0 0 14px;
}

.letter-head h1 {
  margin: 0;
  color: var(--ink);
  font-size: clamp(34px, 5vw, 52px);
  line-height: 1.12;
  letter-spacing: 0;
}

.dek {
  max-width: 700px;
  margin: 20px 0 0;
  color: var(--muted);
  font-size: clamp(16px, 1.5vw, 18px);
  line-height: 1.72;
}

.byline {
  display: flex;
  align-items: center;
  margin-top: 24px;
  border-left: 3px solid var(--green);
  padding-left: 12px;
}

.byline strong,
.byline span {
  display: block;
}

.byline strong {
  line-height: 1.2;
}

.byline span {
  color: var(--muted);
  font-size: 12px;
}

.letter-body {
  padding-top: clamp(28px, 4vw, 42px);
  font-size: clamp(17px, 1.45vw, 18px);
  line-height: 1.92;
}

.letter-body p {
  margin: 0;
}

.letter-body p + p,
.letter-body blockquote + p,
.letter-body p + blockquote,
.letter-body blockquote + blockquote {
  margin-top: 1.45em;
}

.letter-body strong {
  color: var(--green-deep);
  font-weight: 950;
}

.letter-body blockquote {
  margin: 1.7em 0;
  border-left: 4px solid var(--green);
  padding: 4px 0 4px 20px;
  color: var(--muted);
  font-size: 0.96em;
}

.letter-body .align-center {
  text-align: center;
}

.signoff {
  width: max-content;
  margin-top: 2em !important;
  border-top: 3px solid var(--gold);
  padding-top: 14px;
  color: var(--green-deep);
  font-size: clamp(20px, 2vw, 24px);
  font-weight: 950;
}

.subscribe-panel {
  display: grid;
  max-width: 760px;
  grid-template-columns: 1fr auto;
  gap: 24px;
  align-items: center;
  margin: clamp(44px, 7vw, 68px) auto 0;
  border: 1px solid rgba(35, 74, 37, 0.26);
  border-radius: 8px;
  padding: clamp(20px, 3vw, 28px);
  background: rgba(255, 248, 237, 0.76);
  box-shadow: 0 18px 50px rgba(36, 24, 16, 0.08);
}

.subscribe-panel h2 {
  margin: 0;
  font-size: clamp(22px, 2.4vw, 28px);
  line-height: 1.14;
}

.subscribe-panel p:not(.kicker) {
  max-width: 520px;
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 15px;
}

.post-subscribe-box {
  width: min(100%, 420px);
}

.post-subscribe-form {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 8px;
}

.post-subscribe-form input,
.post-subscribe-form button {
  min-height: 40px;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 0 15px;
  font: inherit;
  font-size: 14px;
}

.post-subscribe-form input {
  min-width: 0;
  background: rgba(255, 248, 237, 0.78);
}

.post-subscribe-form button {
  border-color: var(--green);
  background: var(--green);
  color: #fff;
  font-weight: 950;
  white-space: nowrap;
}

.post-subscribe-form button:hover {
  background: var(--green-deep);
}

.post-subscribe-form input:disabled,
.post-subscribe-form button:disabled {
  cursor: not-allowed;
  opacity: 0.58;
}

.post-subscribe-note {
  margin: 10px 0 0;
  color: var(--muted);
  font-size: 13px;
}

.post-subscribe-note.success {
  color: var(--green);
  font-weight: 800;
}

.post-subscribe-note.error {
  color: #9b2f22;
  font-weight: 800;
}

.letter-footer {
  display: flex;
  width: min(100%, 1120px);
  margin: 0 auto;
  justify-content: space-between;
  gap: 16px;
  padding: 28px clamp(20px, 5vw, 56px) 38px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 13px;
}

.letter-footer a {
  text-underline-offset: 4px;
}

@media (max-width: 720px) {
  .letter-nav {
    align-items: flex-start;
    padding: 12px;
  }

  .letter-mark {
    width: 38px;
    height: 38px;
  }

  .letter-nav nav {
    flex-wrap: wrap;
    justify-content: flex-end;
  }

  .letter-nav nav a {
    padding: 6px 9px;
    font-size: 12px;
  }

  .letter-shell {
    padding-top: 30px;
  }

  .back-link {
    margin-bottom: 20px;
  }

  .letter-body {
    font-size: 16px;
  }

  .subscribe-panel {
    grid-template-columns: 1fr;
  }

  .post-subscribe-box {
    width: 100%;
  }

  .letter-footer {
    flex-direction: column;
  }
}