:root {
  --navy: #12283e;
  --deep: #0b1c2d;
  --blue: #0758b8;
  --gold: #edb72c;
  --ink: #162b40;
  --muted: #617180;
  --bg: #f5f7f9;
  --white: #fff;
  --line: #dce3e9;
  --radius: 12px;
  --width: 1220px;
}
* {
  box-sizing: border-box;
}
html {
  scroll-behavior: smooth;
  scroll-padding-top: 105px;
}
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: Arial,"PingFang SC","Microsoft YaHei",sans-serif;
  font-size: 16px;
  line-height: 1.75;
}
a {
  color: var(--blue);
  text-decoration: none;
}
a,button,summary {
  transition: background .2s,color .2s,border-color .2s,transform .2s;
}
a: hover {;
  color: #033c80;
}
a: active,button:active {;
  transform: translateY(1px);
}
a: focus-visible,button:focus-visible,summary:focus-visible {;
  outline: 3px solid var(--gold);
  outline-offset: 4px;
}
button {
  font: inherit;
  cursor: pointer;
}
h1,h2,h3,h4,p {
  margin: 0;
}
h1,h2,h3,h4 {
  line-height: 1.3;
  color: var(--ink);
}
h1 {
  font-size: clamp(2rem,3.2vw,2.8rem);
  letter-spacing: -.035em;
  font-weight: 800;
}
h2 {
  font-size: clamp(1.35rem,2vw,1.8rem);
  letter-spacing: -.02em;
}
h3 {
  font-size: 1.16rem;
}
p {
  color: #425569;
}
img,svg {
  display: block;
  max-width: 100%;
  height: auto;
}
button,a {
  overflow-wrap: anywhere;
}
.container {
  width: min(var(--width),calc(100% - 48px));
  margin: auto;
}
.site-header {
  position: sticky;
  top: 0;
  z-index: 30;
  background: var(--white);
  box-shadow: 0 1px 0 var(--line),0 4px 16px #0b1c2d08;
}
.header-inner {
  min-height: 88px;
  display: flex;
  align-items: center;
  gap: 35px;
  justify-content: space-between;
}
.logo {
  display: inline-flex;
  align-items: center;
  font-size: 2.7rem;
  line-height: 1;
  font-style: italic;
  letter-spacing: -.08em;
  color: var(--blue);
  font-weight: 900;
  flex-shrink: 0;
}
.logo span {
  color: var(--gold);
  font-size: 3.1rem;
  letter-spacing: -.12em;
  margin-right: 5px;
}
.logo:hover {
  color: var(--blue);
}
.nav {
  display: flex;
  gap: 4px;
  align-items: center;
}
.nav a {
  color: var(--ink);
  padding: 12px 13px;
  font-size: .88rem;
  font-weight: 700;
  border-bottom: 3px solid transparent;
}
.nav a:hover {
  color: var(--blue);
  background: #f1f6fc;
}
.nav a[aria-current=page] {
  color: var(--blue);
  border-color: var(--gold);
}
.header-tools {
  display: flex;
  align-items: center;
  gap: 12px;
}
.language-switch {
  display: flex;
  align-items: center;
  gap: 2px;
  padding: 3px;
  border: 1px solid var(--line);
  border-radius: 6px;
}
.language-switch a {
  padding: 6px 9px;
  font-size: .75rem;
  white-space: nowrap;
  color: #56677a;
  line-height: 1.3;
}
.language-switch a[aria-current=true] {
  background: var(--navy);
  color: white;
  border-radius: 3px;
}
.language-switch a:hover {
  background: #e8eff7;
  color: var(--ink);
}
.menu-toggle {
  display: none;
  border: 1px solid var(--line);
  border-radius: 5px;
  background: white;
  color: var(--ink);
  padding: 8px 11px;
  font-size: .8rem;
}
.eyebrow {
  display: flex;
  align-items: center;
  gap: 9px;
  color: var(--blue);
  font-size: .74rem;
  letter-spacing: .12em;
  font-weight: bold;
  text-transform: uppercase;
  margin-bottom: 17px;
}
.eyebrow:before {
  content: '';
  height: 2px;
  width: 25px;
  background: var(--gold);
}
.hero {
  padding: 38px 0 32px;
  background: #eef3f8;
  border-bottom: 1px solid var(--line);
}
.hero-layout {
  display: grid;
  grid-template-columns: .92fr 1.4fr;
  gap: 40px;
  align-items: center;
}
.hero-copy .subtitle {
  font-size: 1.02rem;
  margin-top: 22px;
  max-width: 450px;
}
.hero-figure {
  margin: 0;
  background: var(--navy);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 12px 30px #12283e16;
  border: 1px solid #d1dbe6;
}
.hero-figure img {
  width: 100%;
  aspect-ratio: 800/450;
  object-fit: contain;
}
.hero-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 25px;
}
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 11px 19px;
  border: 1px solid var(--line);
  background: white;
  color: var(--ink);
  font-size: .88rem;
  line-height: 1.4;
  font-weight: bold;
  border-radius: 6px;
}
.button.primary {
  background: var(--blue);
  color: white;
  border-color: var(--blue);
}
.button:hover {
  background: #e7eef6;
  color: var(--ink);
  transform: translateY(-2px);
}
.button.primary:hover {
  background: #03428e;
  color: white;
}
.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 15px;
  font-size: .75rem;
  color: var(--muted);
  margin-top: 22px;
}
.hero-meta span+span {
  border-left: 1px solid #b9c5d3;
  padding-left: 15px;
}
.article-intro {
  max-width: 940px;
  margin: 30px auto 0;
  padding: 24px 0 0;
  border-top: 1px solid #d4dfe9;
}
.article-intro p+p {
  margin-top: 14px;
}
.breadcrumbs {
  font-size: .78rem;
  color: var(--muted);
  display: flex;
  gap: 8px;
  margin-bottom: 24px;
}
.breadcrumbs a {
  color: var(--muted);
}
section {
  padding: 38px 0;
  border-bottom: 1px solid var(--line);
}
section: nth-of-type(even) {;
  background: white;
}
.section-top {
  display: flex;
  gap: 18px;
  align-items: flex-start;
  margin-bottom: 23px;
}
.section-number {
  padding-top: 4px;
  color: #8292a3;
  font-size: .77rem;
  font-weight: bold;
  min-width: 25px;
}
.section-heading {
  max-width: 900px;
}
.section-heading .topic-tag {
  color: var(--blue);
  font-size: .7rem;
  font-weight: bold;
  letter-spacing: .09em;
  text-transform: uppercase;
  margin-bottom: 8px;
  display: block;
}
.topic-matrix {
  display: grid;
  grid-template-columns: repeat(4,minmax(0,1fr));
  gap: 15px;
}
.topic-card {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--line);
  border-radius: 9px;
  overflow: hidden;
  background: white;
  color: var(--ink);
  box-shadow: 0 3px 12px #12283e05;
}
.topic-card:hover {
  border-color: #9cb6d6;
  transform: translateY(-3px);
  box-shadow: 0 8px 24px #12283e10;
  color: var(--ink);
}
.topic-card img {
  width: 100%;
  aspect-ratio: 800/450;
  object-fit: contain;
}
.topic-card-content {
  padding: 16px;
}
.topic-card-content strong {
  display: block;
  font-size: 1rem;
  color: var(--ink);
}
.topic-card-content p {
  font-size: .8rem;
  margin-top: 7px;
  line-height: 1.6;
}
.topic-card .card-label {
  color: var(--blue);
  font-size: .7rem;
  font-weight: bold;
  display: flex;
  justify-content: space-between;
  margin-top: 14px;
}
.article-section .reading-grid {
  display: grid;
  grid-template-columns: minmax(0,1.3fr) minmax(260px,.85fr);
  gap: 42px;
  align-items: start;
}
.prose {
  max-width: 930px;
  margin: auto;
  min-width: 0;
}
.prose p {
  margin-bottom: 15px;
  overflow-wrap: anywhere;
}
.prose h3 {
  margin: 27px 0 12px;
}
.prose h4 {
  margin: 22px 0 10px;
}
.prose ul,.prose ol {
  margin: 15px 0 20px;
  padding-left: 23px;
  color: #425569;
}
.prose li {
  margin: 7px 0;
}
.prose li::marker {
  color: var(--blue);
}
.prose .subsection-title {
  margin-top: 37px;
  padding-top: 27px;
  border-top: 1px solid var(--line);
  font-size: 1.3rem;
}
.article-figure {
  margin: 24px 0;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 9px;
  overflow: hidden;
}
.article-figure img {
  width: 100%;
  aspect-ratio: 800/450;
  object-fit: contain;
}
.article-figure figcaption {
  padding: 10px 15px;
  color: #617180;
  font-size: .76rem;
  line-height: 1.6;
  background: #f9fbfd;
}
.reading-grid>.article-figure {
  margin-top: 0;
}
.table-scroll {
  overflow-x: auto;
  max-width: 100%;
  margin: 20px 0 24px;
  border: 1px solid var(--line);
  border-radius: 9px;
  background: #fff;
}
.table-scroll:focus-visible {
  outline: 3px solid var(--gold);
  outline-offset: 3px;
}
table {
  border-collapse: collapse;
  width: 100%;
  font-size: .87rem;
  line-height: 1.65;
  text-align: left;
}
th {
  background: var(--navy);
  color: white;
  font-size: .81rem;
  white-space: nowrap;
  padding: 13px 17px;
}
td {
  padding: 13px 17px;
  border-bottom: 1px solid var(--line);
  color: #425569;
  min-width: 150px;
}
td: first-child {;
  font-weight: bold;
  color: var(--ink);
}
tr: last-child td {;
  border-bottom: 0;
}
tbody tr:nth-child(even) {
  background: #f5f8fb;
}
tbody tr:hover {
  background: #eef4fa;
}
.compact-table td {
  min-width: 0;
}
.info-rail {
  padding: 23px;
  border-left: 3px solid var(--gold);
  background: #f0f5fa;
  color: #40566f;
  font-size: .9rem;
  margin: 22px 0;
}
.faq {
  max-width: 930px;
  margin: auto;
}
.faq details {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  margin-bottom: 11px;
  overflow: hidden;
}
.faq summary {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  padding: 16px 19px;
  font-size: .96rem;
  font-weight: bold;
  cursor: pointer;
  list-style: none;
}
.faq summary:hover {
  background: #f3f7fb;
}
.faq summary::-webkit-details-marker {
  display: none;
}
.faq summary:after {
  content: '+';
  color: var(--blue);
  font-size: 1.2rem;
  line-height: 1.2;
  flex: none;
}
.faq details[open] summary:after {
  content: '−';
}
.faq details .answer {
  padding: 0 19px 18px;
  font-size: .95rem;
}
.faq .answer p+p {
  margin-top: 12px;
}
.source-links {
  max-width: 930px;
  margin: 20px auto 0;
  padding-top: 16px;
  border-top: 1px solid var(--line);
  font-size: .77rem;
  color: var(--muted);
}
.source-links a {
  display: inline-block;
  margin-right: 20px;
}
.conclusion .prose {
  padding: 27px;
  background: #edf3f9;
  border: 1px solid #d1dfe9;
  border-radius: 9px;
}
.site-footer {
  padding: 35px 0 20px;
  background: var(--deep);
  color: #e6ecf3;
  border-top: 3px solid var(--gold);
}
.footer-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 30px;
  padding-bottom: 24px;
}
.footer-logo {
  color: white;
  font-size: 2.25rem;
}
.footer-logo:hover {
  color: white;
}
.footer-logo span {
  font-size: 2.6rem;
}
.footer-text {
  max-width: 480px;
  font-size: .82rem;
  color: #aebdcc;
}
.footer-links {
  display: flex;
  gap: 20px;
  font-size: .79rem;
  flex-wrap: wrap;
}
.footer-links a {
  color: #d4dfeb;
}
.footer-links a:hover {
  color: var(--gold);
}
.copyright {
  padding-top: 18px;
  border-top: 1px solid #294057;
  display: flex;
  justify-content: space-between;
  gap: 20px;
  font-size: .73rem;
  color: #9eb0c2;
}
.skip-link {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 100;
  transform: translateY(-200%);
  background: var(--gold);
  color: var(--ink);
  padding: 10px 15px;
  border-radius: 6px;
}
.skip-link:focus {
  transform: none;
}
.backtop {
  width: 34px;
  height: 34px;
  border: 1px solid #496078;
  border-radius: 6px;
  display: grid;
  place-items: center;
  font-size: 1.2rem;
  color: #fff;
}
.backtop:hover {
  background: #29425c;
  color: white;
}
html[lang^=zh] h1 {
  font-size: clamp(1.8rem,3vw,2.45rem);
  letter-spacing: 0;
}
html[lang^=zh] body {
  line-height: 1.9;
}
html[lang^=zh] .prose h3 {
  line-height: 1.5;
}
@media(max-width:1024px) {
  .header-inner {
    gap: 20px;
  }
  .nav a {
    padding: 12px 9px;
    font-size: .82rem;
  }
  .hero-layout {
    gap: 28px;
    grid-template-columns: 1fr 1.25fr;
  }
  .hero-copy .subtitle {
    font-size: .96rem;
  }
  .language-switch a {
    padding: 6px;
    font-size: .7rem;
  }
  .logo {
    font-size: 2.3rem;
  }
  .logo span {
    font-size: 2.7rem;
  }
  .topic-matrix {
    gap: 12px;
  }
  .topic-card-content {
    padding: 13px;
  }
  .article-section .reading-grid {
    gap: 25px;
    grid-template-columns: 1.1fr .9fr;
  }
}
@media(max-width:768px) {
  html {
    scroll-padding-top: 85px;
  }
  .container {
    width: calc(100% - 32px);
  }
  .header-inner {
    min-height: 76px;
    flex-wrap: wrap;
    gap: 0;
    padding: 12px 0;
  }
  .header-tools {
    margin-left: auto;
    gap: 10px;
  }
  .menu-toggle {
    display: block;
  }
  .nav {
    display: none;
    width: 100%;
    order: 3;
    flex-direction: column;
    align-items: stretch;
    padding: 13px 0 3px;
  }
  .nav.open {
    display: flex;
  }
  .nav a {
    padding: 10px 12px;
    font-size: .9rem;
    border-left: 3px solid transparent;
    border-bottom: 0;
  }
  .nav a[aria-current=page] {
    border-left-color: var(--gold);
    background: #f0f5fa;
  }
  .hero {
    padding: 28px 0;
  }
  .hero-layout {
    grid-template-columns: 1fr;
    gap: 26px;
  }
  .hero-copy .subtitle {
    max-width: 680px;
    font-size: 1rem;
  }
  .hero-figure {
    max-width: 800px;
    width: 100%;
    margin: auto;
  }
  .hero-actions {
    margin-top: 20px;
  }
  .article-intro {
    margin-top: 24px;
    padding-top: 20px;
  }
  .topic-matrix {
    grid-template-columns: repeat(2,minmax(0,1fr));
  }
  .article-section .reading-grid {
    grid-template-columns: 1fr;
  }
  .reading-grid>.article-figure {
    max-width: 800px;
  }
  .section-top {
    gap: 12px;
  }
  section {
    padding: 30px 0;
  }
  .footer-top {
    flex-wrap: wrap;
    gap: 20px;
  }
  .footer-text {
    flex: 1;
    max-width: 100%;
    min-width: 230px;
  }
  .footer-links {
    width: 100%;
  }
  .copyright {
    flex-direction: column;
    gap: 8px;
  }
  .prose h3 {
    margin-top: 23px;
  }
}
@media(max-width:520px) {
  .container {
    width: calc(100% - 24px);
  }
  .header-tools {
    gap: 7px;
  }
  .language-switch a {
    font-size: .68rem;
    padding: 6px;
  }
  .logo {
    font-size: 2.1rem;
  }
  .logo span {
    font-size: 2.5rem;
  }
  .menu-toggle {
    font-size: .72rem;
    padding: 6px 8px;
  }
  .header-inner {
    min-height: 70px;
  }
  .hero {
    padding-top: 22px;
  }
  .hero-layout {
    gap: 22px;
  }
  h1 {
    font-size: 2rem;
  }
  .hero-copy .subtitle {
    font-size: .96rem;
  }
  .hero-meta {
    gap: 10px;
    font-size: .69rem;
  }
  .hero-meta span+span {
    padding-left: 10px;
  }
  .hero-actions .button {
    flex: 1;
    padding: 11px 14px;
    font-size: .81rem;
  }
  .topic-card-content strong {
    font-size: .91rem;
  }
  .topic-card-content p {
    font-size: .77rem;
  }
  .topic-card .card-label {
    font-size: .65rem;
  }
  .section-number {
    display: none;
  }
  .section-top {
    margin-bottom: 19px;
  }
  h2 {
    font-size: 1.35rem;
  }
  .prose {
    font-size: .96rem;
  }
  .prose h3 {
    font-size: 1.06rem;
  }
  .table-scroll {
    margin: 17px 0;
  }
  th,td {
    padding: 11px 13px;
  }
  td {
    min-width: 135px;
  }
  .faq summary {
    padding: 14px 15px;
    font-size: .91rem;
  }
  .faq details .answer {
    padding: 0 15px 16px;
    font-size: .91rem;
  }
  .conclusion .prose {
    padding: 20px;
  }
  .footer-text {
    min-width: 100%;
    font-size: .79rem;
  }
  .breadcrumbs {
    font-size: .72rem;
    flex-wrap: wrap;
  }
  .source-links a {
    margin-bottom: 8px;
  }
  .article-figure figcaption {
    font-size: .72rem;
  }
  .topic-matrix {
    gap: 10px;
  }
}
@media(prefers-reduced-motion:reduce) {
  html {
    scroll-behavior: auto;
  }
  *,*:before,*:after {
    transition: none!important;
    animation: none!important;
  }
}
.banner-grid {
  display: grid;
  grid-template-columns: repeat(2,minmax(0,1fr));
  gap: 20px;
  margin-top: 24px;
}
.promo-banner {
  margin: 0;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 6px 20px #12283e0b;
}
.promo-banner img {
  width: 100%;
  height: auto;
  aspect-ratio: 990/320;
  object-fit: contain;
}
.promo-banner figcaption {
  padding: 10px 16px;
  color: var(--ink);
  font-size: .85rem;
  font-weight: 700;
}
.promo-note {
  margin-top: 12px;
  max-width: 850px;
}
.promotion-section {
  background: #edf3fa;
}
.promo-banner:hover {
  box-shadow: 0 10px 26px #12283e18;
}
.article-section .banner-grid {
  margin-top: 30px;
}
@media(max-width:768px) {
  .banner-grid {
    grid-template-columns: 1fr;
    gap: 16px;
  }
}
@media(max-width:520px) {
  .promo-banner {
    border-radius: 8px;
  }
  .promo-banner figcaption {
    padding: 8px 12px;
    font-size: .78rem;
  }
}

/* Compact language selector and persistent account actions. */
.header-inner  {
  gap: 20px;
}
.header-tools  {
  gap: 10px;
  flex-shrink: 0;
}
.auth-actions  {
  display: flex;
  gap: 8px;
  align-items: center;
}
.auth-button  {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 38px;
  padding: 7px 14px;
  font-size: .82rem;
  font-weight: 700;
  line-height: 1.3;
  border: 1px solid var(--blue);
  border-radius: 6px;
  white-space: nowrap;
}
.auth-register  {
  background: var(--blue);
  color: white;
}
.auth-register:hover  {
  background: #03428e;
  color: white;
}
.auth-login  {
  background: white;
  color: var(--blue);
}
.auth-login:hover  {
  background: #edf4fd;
  color: #03428e;
}
.language-dropdown  {
  position: relative;
}
.language-trigger  {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: 50%;
  background: white;
  color: var(--navy);
  cursor: pointer;
  list-style: none;
}
.language-trigger::-webkit-details-marker  {
  display: none;
}
.language-trigger:hover, .language-dropdown[open] .language-trigger  {
  background: #edf4fd;
  border-color: var(--blue);
  color: var(--blue);
}
.language-menu  {
  position: absolute;
  right: 0;
  top: calc(100% + 10px);
  z-index: 50;
  width: 155px;
  padding: 6px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: white;
  box-shadow: 0 10px 30px #12283e24;
}
.language-menu a  {
  display: block;
  padding: 9px 12px;
  border-radius: 5px;
  font-size: .8rem;
  line-height: 1.5;
  color: var(--ink);
}
.language-menu a:hover  {
  background: #edf4fd;
  color: var(--blue);
}
.language-menu a[aria-current=true]  {
  background: var(--navy);
  color: white;
}
.menu-toggle  {
  width: 36px;
  height: 36px;
  padding: 0;
  font-size: 19px;
  line-height: 1;
}
@media(max-width:1100px)  {
  .header-inner  {
    flex-wrap: wrap;
    min-height: 76px;
    gap: 0;
    padding: 12px 0;
  }
  .header-tools  {
    margin-left: auto;
  }
  .menu-toggle  {
    display: block;
  }
  .nav  {
    display: none;
    order: 3;
    width: 100%;
    flex-direction: column;
    align-items: stretch;
    padding: 13px 0 3px;
  }
  .nav.open  {
    display: flex;
  }
  .nav a  {
    border-bottom: 0;
    border-left: 3px solid transparent;
  }
  .nav a[aria-current=page]  {
    border-left-color: var(--gold);
    background: #f0f5fa;
  }
}
@media(max-width:520px)  {
  .header-tools  {
    gap: 7px;
  }
  .auth-actions  {
    gap: 5px;
  }
  .auth-button  {
    min-height: 34px;
    padding: 7px 10px;
    font-size: .73rem;
  }
  .language-trigger, .menu-toggle  {
    width: 32px;
    height: 32px;
  }
  .header-inner  {
    min-height: 68px;
  }
}
@media(max-width:380px)  {
  .header-tools  {
    gap: 5px;
  }
  .auth-button  {
    padding: 7px 8px;
    font-size: .69rem;
  }
  .logo  {
    font-size: 1.8rem;
  }
  .logo span  {
    font-size: 2.2rem;
  }
}