:root {
  --color-ice-50: #F7FBFD;
  --color-ice-200: #D6EDF2;
  --color-glacier-600: #167A8C;
  --color-glacier-900: #0E2E38;
  --color-sun-500: #F2763A;
  --color-sun-100: #FFE7D6;
  --color-ink-900: #162A32;
  --color-ink-600: #3D545E;
  --color-line-300: #C0D6DB;
  --color-white: #FFFFFF;

  --font-heading: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-weight-heading: 900;
  --font-weight-body: 300;

  --fs-h1: clamp(2.8rem, 6vw, 5.2rem);
  --fs-h2: clamp(2rem, 4vw, 3.2rem);
  --fs-h3: clamp(1.4rem, 2.5vw, 2rem);
  --body-size: 1rem;
  --line-height: 1.7;
  --letter-spacing: 0.01em;

  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.5rem;
  --space-6: 2rem;
  --space-8: 4rem;

  --container-max: 72rem;
  --border-width: 1px;
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  font-family: var(--font-body);
  font-size: var(--body-size);
  font-weight: var(--font-weight-body);
  line-height: var(--line-height);
  letter-spacing: var(--letter-spacing);
  color: var(--color-ink-900);
  background-color: var(--color-ice-50);
  -webkit-font-smoothing: antialiased;
}

body,
h1, h2, h3, h4, h5, h6,
p, ul, ol, dl, figure, blockquote {
  margin: 0;
}

ul[class],
ol[class] {
  padding: 0;
  list-style: none;
}

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

button,
input,
select,
textarea {
  font: inherit;
}

a {
  color: var(--color-glacier-600);
  text-decoration-thickness: 0.08em;
  text-underline-offset: 0.2em;
  transition: color 0.2s ease;
}

a:hover,
a:focus-visible {
  color: var(--color-sun-500);
}

h1, h2, h3 {
  font-family: var(--font-heading);
  font-weight: var(--font-weight-heading);
  line-height: 1.15;
}

h1 { font-size: var(--fs-h1); }
h2 { font-size: var(--fs-h2); }
h3 { font-size: var(--fs-h3); }

:focus-visible {
  outline: 3px solid var(--color-sun-500);
  outline-offset: 2px;
}

#main-content:focus {
  outline: none;
}

main {
  flex: 1;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.container {
  width: 100%;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--space-4);
}

@media (min-width: 48rem) {
  .container {
    padding-inline: var(--space-6);
  }
}

.site-header {
  position: relative;
  background: var(--color-ice-50);
  border-top: 4px solid var(--color-sun-500);
}

.skip-link {
  position: absolute;
  left: var(--space-4);
  top: -100%;
  z-index: 1000;
  background: var(--color-sun-500);
  color: var(--color-white);
  padding: var(--space-3) var(--space-4);
  font-weight: bold;
  text-decoration: none;
  transition: top 0.2s ease;
}

.skip-link:focus {
  top: var(--space-4);
}

.header-topbar {
  border-bottom: 1px solid var(--color-line-300);
  padding-block: var(--space-3);
  background: var(--color-ice-50);
}

.header-topbar__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
}

.header-brand {
  margin: 0;
}

.header-brand__link {
  display: inline-flex;
  align-items: baseline;
  gap: var(--space-3);
  text-decoration: none;
  color: var(--color-glacier-900);
}

.header-brand__name {
  font-family: var(--font-heading);
  font-weight: 900;
  font-size: 1.25rem;
  letter-spacing: 0.04em;
}

.header-brand__tagline {
  font-size: 0.8125rem;
  color: var(--color-ink-600);
}

.header-topbar__note {
  font-size: 0.75rem;
  color: var(--color-ink-600);
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

@media (max-width: 40rem) {
  .header-topbar__inner {
    flex-direction: column;
    align-items: flex-start;
  }
}

.header-navbar {
  background: var(--color-glacier-900);
  color: var(--color-white);
}

.header-navbar__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 3.5rem;
  gap: var(--space-4);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 2.5rem;
  height: 2.5rem;
  padding: var(--space-2);
  background: transparent;
  border: 1px solid rgba(255,255,255,0.4);
  border-radius: 0;
  cursor: pointer;
}

.nav-toggle__bar {
  width: 100%;
  height: 2px;
  background: var(--color-white);
}

.site-nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  list-style: none;
}

.site-nav__link {
  display: block;
  padding: var(--space-3) var(--space-4);
  color: var(--color-ice-50);
  font-size: 0.9375rem;
  font-weight: 500;
  text-decoration: none;
  border-bottom: 3px solid transparent;
  transition: color 0.2s ease, border-color 0.2s ease, background-color 0.2s ease;
}

.site-nav__link:hover,
.site-nav__link:focus-visible {
  color: var(--color-sun-100);
  border-bottom-color: var(--color-sun-500);
}

.site-nav__link[aria-current="page"] {
  color: var(--color-sun-100);
  border-bottom-color: var(--color-sun-500);
  background: rgba(255,255,255,0.06);
}

@media (max-width: 47.99rem) {
  .header-navbar__inner {
    flex-wrap: wrap;
    padding-block: var(--space-2);
  }

  .nav-toggle {
    display: flex;
  }

  .site-nav {
    flex-basis: 100%;
    display: none;
  }

  .site-nav[data-open] {
    display: block;
  }

  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    border-top: 1px solid rgba(255,255,255,0.15);
    margin-top: var(--space-2);
  }

  .site-nav__item {
    width: 100%;
  }

  .site-nav__link {
    padding: var(--space-4);
    border-bottom: 1px solid rgba(255,255,255,0.1);
    border-left: 3px solid transparent;
  }

  .site-nav__link[aria-current="page"],
  .site-nav__link:hover,
  .site-nav__link:focus-visible {
    border-left-color: var(--color-sun-500);
    border-bottom-color: rgba(255,255,255,0.1);
  }
}

.site-footer {
  background: var(--color-glacier-900);
  color: var(--color-ice-200);
  font-size: 0.875rem;
  margin-top: auto;
}

.site-footer__inner {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-6);
  padding-block: var(--space-8);
}

@media (min-width: 48rem) {
  .site-footer__inner {
    grid-template-columns: 1.5fr 1fr 1.5fr;
  }
}

.site-footer__brand,
.site-footer__links,
.site-footer__contact {
  min-width: 0;
}

.site-footer__name {
  font-family: var(--font-heading);
  font-weight: 900;
  font-size: 1.5rem;
  color: var(--color-white);
  line-height: 1.2;
}

.site-footer__tagline {
  margin-top: var(--space-2);
  color: var(--color-ice-200);
}

.site-footer__title {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--color-sun-500);
  border-bottom: 1px solid rgba(255,255,255,0.15);
  padding-bottom: var(--space-2);
  margin-bottom: var(--space-4);
}

.site-footer__links ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-footer__links li {
  margin-bottom: var(--space-2);
}

.site-footer__links a {
  color: var(--color-ice-200);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.2s ease, border-color 0.2s ease;
}

.site-footer__links a:hover,
.site-footer__links a:focus-visible {
  color: var(--color-white);
  border-bottom-color: var(--color-sun-500);
}

.site-footer__contact p {
  margin: var(--space-1) 0;
  line-height: 1.6;
}

.site-footer__bottom {
  border-top: 1px solid rgba(255,255,255,0.15);
  padding-block: var(--space-4);
  font-size: 0.75rem;
  color: var(--color-ice-200);
}

.site-footer__copyright,
.site-footer__legal {
  margin: var(--space-1) 0;
}

.site-footer__legal a {
  color: var(--color-ice-200);
  text-decoration: none;
  border-bottom: 1px dotted transparent;
}

.site-footer__legal a:hover,
.site-footer__legal a:focus-visible {
  color: var(--color-white);
  border-bottom-color: var(--color-sun-500);
}

.back-to-top {
  position: fixed;
  right: var(--space-4);
  bottom: var(--space-4);
  z-index: 1000;
  display: inline-block;
  padding: var(--space-3) var(--space-4);
  background: var(--color-glacier-600);
  color: var(--color-white);
  border: none;
  font-family: var(--font-body);
  font-size: 0.8125rem;
  line-height: 1;
  text-decoration: none;
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(14,46,56,0.2);
  opacity: 0;
  transform: translateY(8px);
  pointer-events: none;
  transition: opacity 0.2s ease, transform 0.2s ease, background-color 0.2s ease;
}

.back-to-top.is-visible {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.back-to-top:hover,
.back-to-top:focus-visible {
  background: var(--color-sun-500);
}

.section {
  padding-block: var(--space-8);
}

.section--muted {
  background: var(--color-ice-200);
}

.section-title {
  font-family: var(--font-heading);
  font-size: var(--fs-h2);
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -0.01em;
  margin-bottom: var(--space-5);
}

.section-title::before {
  content: attr(data-index);
  display: block;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.2em;
  color: var(--color-sun-500);
  margin-bottom: var(--space-2);
}

.grid {
  display: grid;
  gap: var(--space-6);
}

.grid--2 {
  grid-template-columns: repeat(2, 1fr);
}

.grid--3 {
  grid-template-columns: repeat(3, 1fr);
}

.grid--aside {
  grid-template-columns: 2fr 1fr;
}

@media (max-width: 47.99rem) {
  .grid--2,
  .grid--3,
  .grid--aside {
    grid-template-columns: 1fr;
  }
}

.card {
  background: var(--color-white);
  border: var(--border-width) solid var(--color-line-300);
  border-radius: 0;
  padding: var(--space-6);
  transition: box-shadow 0.2s ease, transform 0.2s ease, border-color 0.2s ease;
}

.card:hover {
  box-shadow: 0 6px 24px rgba(14,46,56,0.08);
  transform: translateY(-2px);
  border-color: var(--color-glacier-600);
}

.btn {
  display: inline-block;
  padding: var(--space-3) var(--space-6);
  background: var(--color-glacier-600);
  color: var(--color-white);
  border: 2px solid var(--color-glacier-600);
  border-radius: 0;
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.25;
  font-weight: 700;
  text-decoration: none;
  text-align: center;
  cursor: pointer;
  transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease, transform 0.2s ease;
}

.btn:hover {
  background: var(--color-sun-500);
  border-color: var(--color-sun-500);
  color: var(--color-white);
  transform: translateY(-2px);
}

.btn:focus-visible {
  outline: 3px solid var(--color-sun-500);
  outline-offset: 2px;
}

.btn--secondary {
  background: transparent;
  color: var(--color-glacier-600);
}

.btn--secondary:hover {
  background: var(--color-glacier-600);
  color: var(--color-white);
}

.btn--light {
  background: var(--color-white);
  color: var(--color-glacier-900);
  border-color: var(--color-white);
}

.btn--light:hover {
  background: var(--color-sun-100);
  border-color: var(--color-sun-100);
  color: var(--color-glacier-900);
}

.tag {
  display: inline-block;
  padding: var(--space-1) var(--space-3);
  background: var(--color-sun-500);
  color: var(--color-white);
  font-size: 0.75rem;
  font-weight: 700;
  line-height: 1.4;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.tag--new {
  background: var(--color-glacier-600);
}

.tag--hot {
  background: var(--color-sun-500);
}

.prose {
  max-width: 70ch;
  font-size: 1.0625rem;
  line-height: var(--line-height);
}

.prose p {
  margin-bottom: var(--space-5);
}

.prose h2,
.prose h3,
.prose h4 {
  margin-top: var(--space-6);
  margin-bottom: var(--space-3);
}

.prose ul,
.prose ol {
  margin-bottom: var(--space-5);
  padding-left: 1.25rem;
}

.prose li {
  margin-bottom: var(--space-2);
}

.breadcrumb {
  padding-block: var(--space-4);
}

.breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  list-style: none;
  margin: 0;
  padding: 0;
}

.breadcrumb__item {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
}

.breadcrumb__item + .breadcrumb__item::before {
  content: "/";
  color: var(--color-line-300);
}

.breadcrumb__link {
  color: var(--color-glacier-600);
  text-decoration: none;
}

.breadcrumb__link[aria-current="page"] {
  color: var(--color-ink-600);
}

.media {
  position: relative;
  overflow: hidden;
  background: var(--color-ice-200);
}

.media--ratio-169 {
  aspect-ratio: 16 / 9;
}

.media--ratio-43 {
  aspect-ratio: 4 / 3;
}

.media--cover img,
.media__placeholder {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}