:root {
  --ink: #17212a;
  --ink-soft: #566474;
  --paper: #ffffff;
  --page: #edf3f0;
  --dark: #111a22;
  --green: #2d6a4f;
  --blue: #4388ef;
  --gold: #d49a28;
  --line: rgba(23, 33, 42, 0.14);
  --container: min(1120px, calc(100vw - 40px));
  --reading: 760px;
  --font-ui: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--page);
  font-family: var(--font-ui);
  line-height: 1.8;
}

button {
  font: inherit;
}

img {
  display: block;
  max-width: 100%;
}

a {
  color: inherit;
  text-decoration: none;
}

.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 100;
  padding: 8px 12px;
  color: var(--dark);
  background: #fff;
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: absolute;
  inset: 0 0 auto;
  z-index: 10;
  color: #fff;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: var(--container);
  min-height: 76px;
  margin: 0 auto;
  border-bottom: 1px solid rgba(255, 255, 255, 0.14);
}

.brand,
.header-actions,
.language-button,
.back-link,
.signature,
.footer-inner {
  display: flex;
  align-items: center;
}

.brand {
  gap: 11px;
  font-weight: 750;
}

.brand img {
  width: 38px;
  height: 38px;
}

.brand small {
  color: rgba(255, 255, 255, 0.6);
  font-size: 0.78rem;
  font-weight: 600;
}

.header-actions {
  gap: 18px;
}

.language-picker {
  position: relative;
}

.language-button {
  min-height: 40px;
  gap: 8px;
  padding: 6px 10px;
  border: 1px solid rgba(255, 255, 255, 0.18);
  border-radius: 6px;
  color: rgba(255, 255, 255, 0.82);
  background: rgba(255, 255, 255, 0.05);
  cursor: pointer;
  font-size: 0.86rem;
  font-weight: 650;
  transition: color 160ms ease, border-color 160ms ease, background 160ms ease;
}

.language-button:hover,
.language-button[aria-expanded="true"] {
  color: #fff;
  border-color: rgba(255, 255, 255, 0.34);
  background: rgba(255, 255, 255, 0.1);
}

.language-button > img {
  width: 18px;
  height: 18px;
}

.language-button .chevron {
  transition: transform 160ms ease;
}

.language-button[aria-expanded="true"] .chevron {
  transform: rotate(180deg);
}

.language-button:focus-visible,
.language-menu button:focus-visible {
  outline: 3px solid rgba(67, 136, 239, 0.5);
  outline-offset: 2px;
}

.language-menu {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  z-index: 20;
  display: grid;
  width: 184px;
  padding: 6px;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--ink);
  background: #fff;
  box-shadow: 0 18px 44px rgba(4, 12, 18, 0.24);
}

.language-menu[hidden] {
  display: none;
}

.language-menu button {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  min-height: 40px;
  padding: 8px 10px;
  border: 0;
  border-radius: 5px;
  color: var(--ink-soft);
  background: transparent;
  cursor: pointer;
  text-align: left;
}

.language-menu button:hover {
  color: var(--ink);
  background: #edf3f0;
}

.menu-check {
  color: var(--green);
  opacity: 0;
}

.language-menu button[aria-checked="true"] {
  color: var(--ink);
  font-weight: 700;
}

.language-menu button[aria-checked="true"] .menu-check {
  opacity: 1;
}

.back-link {
  min-height: 40px;
  gap: 8px;
  color: rgba(255, 255, 255, 0.76);
  font-size: 0.9rem;
  font-weight: 650;
  transition: color 160ms ease;
}

.back-link:hover {
  color: #fff;
}

.back-link:focus-visible,
.brand:focus-visible,
.site-footer a:focus-visible {
  outline: 3px solid rgba(67, 136, 239, 0.5);
  outline-offset: 4px;
}

.letter-hero {
  display: grid;
  align-items: center;
  min-height: min(620px, calc(100svh - 120px));
  padding: 116px 0 70px;
  color: #fff;
  background: var(--dark);
  overflow: hidden;
}

.hero-inner {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 250px;
  align-items: center;
  gap: 90px;
  width: var(--container);
  margin: 0 auto;
}

.hero-copy {
  max-width: 820px;
}

.eyebrow {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 0 0 24px;
  color: #91baff;
  font-size: 0.88rem;
  font-weight: 750;
}

.eyebrow::before {
  content: "";
  width: 34px;
  height: 2px;
  background: var(--blue);
}

h1 {
  max-width: 780px;
  margin: 0;
  font-size: 4.25rem;
  line-height: 1.12;
  letter-spacing: 0;
  text-wrap: balance;
}

h1 strong {
  color: #ffd06d;
  font-weight: 800;
}

html[lang="en"] h1 {
  font-size: 4rem;
}

html[lang="en"] .letter-body > p {
  text-align: left;
}

html[lang="en"] .opening::first-letter {
  float: none;
  margin: 0;
  color: inherit;
  font-size: inherit;
  font-weight: inherit;
  line-height: inherit;
}

.hero-note {
  margin: 30px 0 0;
  color: rgba(255, 255, 255, 0.63);
  font-size: 1rem;
}

.hero-mark {
  display: grid;
  justify-items: end;
  align-content: center;
  min-height: 300px;
  border-left: 1px solid rgba(255, 255, 255, 0.13);
}

.hero-mark img {
  width: 104px;
  height: 104px;
  margin-bottom: 34px;
}

.year-line {
  width: 100%;
  height: 1px;
  background: rgba(255, 255, 255, 0.18);
}

.year-line span {
  display: block;
  width: 58%;
  height: 2px;
  background: var(--green);
}

.years {
  display: flex;
  align-items: baseline;
  gap: 14px;
  margin-top: 18px;
}

.years b {
  font-size: 2rem;
  letter-spacing: 0;
}

.years span {
  color: rgba(255, 255, 255, 0.55);
  font-size: 0.88rem;
}

.letter {
  padding: 100px 0 118px;
  background: var(--paper);
}

.letter-layout {
  display: grid;
  grid-template-columns: 150px minmax(0, var(--reading));
  justify-content: center;
  gap: 70px;
  width: var(--container);
  margin: 0 auto;
}

.letter-rail {
  align-self: stretch;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 18px;
  padding-top: 10px;
  color: var(--ink-soft);
}

.letter-rail span,
.letter-rail b {
  font-size: 0.68rem;
  letter-spacing: 0;
}

.letter-rail span {
  color: var(--blue);
  font-weight: 800;
}

.letter-rail i {
  width: 1px;
  min-height: 210px;
  background: var(--line);
}

.letter-rail b {
  writing-mode: vertical-rl;
  font-weight: 700;
}

.letter-body {
  min-width: 0;
}

.letter-body > p {
  margin: 0 0 30px;
  color: #364452;
  font-size: 1.08rem;
  line-height: 2;
  text-align: justify;
}

.letter-body .opening {
  margin-bottom: 36px;
  color: var(--ink);
  font-size: 1.24rem;
  font-weight: 620;
  line-height: 1.9;
}

.opening::first-letter {
  float: left;
  margin: 8px 10px 0 0;
  color: var(--green);
  font-size: 3.8rem;
  font-weight: 800;
  line-height: 0.78;
}

blockquote {
  margin: 62px 0;
  padding: 8px 0 8px 30px;
  border-left: 4px solid var(--gold);
}

blockquote p {
  margin: 0;
  color: var(--ink);
  font-size: 2rem;
  font-weight: 750;
  line-height: 1.35;
  letter-spacing: 0;
}

.letter-body .question {
  margin: 54px 0 28px;
  color: var(--green);
  font-size: 1.32rem;
  font-weight: 750;
  text-align: left;
}

.milestone {
  display: grid;
  grid-template-columns: 150px minmax(0, 1fr);
  gap: 30px;
  margin: 62px 0 42px;
  padding: 34px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.milestone > span {
  color: var(--blue);
  font-size: 1.2rem;
  font-weight: 800;
}

.milestone p {
  margin: 0;
  color: #364452;
  font-size: 1.05rem;
  line-height: 1.95;
}

.letter-body .closing-line {
  margin: 62px 0 0;
  color: var(--ink);
  font-size: 2rem;
  font-weight: 780;
  text-align: left;
}

.signature {
  gap: 14px;
  margin-top: 46px;
  padding-top: 30px;
  border-top: 1px solid var(--line);
}

.signature img {
  width: 48px;
  height: 48px;
}

.signature div {
  display: grid;
  gap: 1px;
}

.signature strong {
  font-size: 0.98rem;
}

.signature span {
  color: var(--ink-soft);
  font-size: 0.82rem;
}

.site-footer {
  padding: 28px 0;
  color: rgba(255, 255, 255, 0.64);
  background: var(--dark);
  font-size: 0.82rem;
}

.footer-inner {
  justify-content: space-between;
  gap: 20px;
  width: var(--container);
  margin: 0 auto;
}

.site-footer a {
  color: #fff;
  font-weight: 650;
}

@media (max-width: 900px) {
  .hero-inner {
    grid-template-columns: minmax(0, 1fr) 180px;
    gap: 50px;
  }

  h1 {
    font-size: 3.25rem;
  }

  .letter-layout {
    grid-template-columns: 80px minmax(0, var(--reading));
    gap: 38px;
  }
}

@media (max-width: 640px) {
  :root {
    --container: calc(100vw - 32px);
  }

  .header-inner {
    min-height: 68px;
  }

  .brand small {
    display: none;
  }

  .back-link span {
    position: absolute;
    width: 1px;
    height: 1px;
    overflow: hidden;
    clip: rect(0 0 0 0);
    white-space: nowrap;
  }

  .back-link,
  .language-button {
    justify-content: center;
    width: 40px;
    padding-inline: 0;
  }

  .header-actions {
    gap: 8px;
  }

  .language-button > span,
  .language-button .chevron {
    display: none;
  }

  .letter-hero {
    min-height: min(560px, calc(100svh - 120px));
    padding: 102px 0 46px;
  }

  .hero-inner {
    grid-template-columns: 1fr;
    gap: 34px;
  }

  h1 {
    font-size: 2.5rem;
    line-height: 1.16;
  }

  html[lang="en"] h1 {
    font-size: 2.25rem;
  }

  .hero-note {
    margin-top: 22px;
    font-size: 0.9rem;
  }

  .hero-mark {
    grid-template-columns: 58px minmax(0, 1fr) auto;
    align-items: center;
    gap: 16px;
    min-height: 0;
    border-left: 0;
  }

  .hero-mark img {
    width: 58px;
    height: 58px;
    margin: 0;
  }

  .year-line {
    width: 100%;
  }

  .years {
    margin: 0;
  }

  .years b {
    font-size: 1.3rem;
  }

  .letter {
    padding: 68px 0 78px;
  }

  .letter-layout {
    grid-template-columns: 1fr;
    gap: 0;
  }

  .letter-rail {
    display: none;
  }

  .letter-body > p {
    margin-bottom: 26px;
    font-size: 1rem;
    line-height: 1.92;
    text-align: left;
  }

  .letter-body .opening {
    font-size: 1.08rem;
  }

  .opening::first-letter {
    font-size: 3.3rem;
  }

  blockquote {
    margin: 46px 0;
    padding-left: 20px;
  }

  blockquote p {
    font-size: 1.55rem;
  }

  .letter-body .question {
    margin-top: 42px;
    font-size: 1.18rem;
  }

  .milestone {
    grid-template-columns: 1fr;
    gap: 12px;
    margin: 48px 0 34px;
    padding: 26px 0;
  }

  .milestone p {
    font-size: 1rem;
  }

  .letter-body .closing-line {
    margin-top: 50px;
    font-size: 1.65rem;
  }

  .footer-inner {
    align-items: flex-start;
    flex-direction: column;
  }
}

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

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