/* ============================================================
   EarthOS · Base：重置、排版、布局骨架、页头页脚
   ============================================================ */

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

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 96px;
}

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

body {
  margin: 0;
  background: var(--c-paper);
  color: var(--c-ink);
  font-family: var(--font-sans);
  font-size: var(--fs-body);
  line-height: var(--lh-body);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  overflow-x: clip;
}

/* 极细纸纹：一层固定的噪点叠加，负混合，不参与点击 */
body::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image: var(--grain);
  background-size: 160px 160px;
  opacity: 0.05;
  mix-blend-mode: multiply;
}

img,
svg,
video,
canvas {
  display: block;
  max-width: 100%;
}

img {
  height: auto;
}

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

button {
  cursor: pointer;
  background: none;
  border: 0;
  padding: 0;
}

a {
  color: var(--c-gold-deep);
  text-decoration-color: color-mix(in srgb, var(--c-gold-deep) 45%, transparent);
  text-underline-offset: 0.22em;
  text-decoration-thickness: 1px;
  transition: color var(--dur-1) var(--ease-out),
    text-decoration-color var(--dur-1) var(--ease-out);
}

a:hover {
  color: var(--c-ink);
  text-decoration-color: var(--c-ink);
}

::selection {
  background: var(--c-gold-soft);
  color: var(--c-ink);
}

:focus-visible {
  outline: 2px solid var(--c-focus);
  outline-offset: 3px;
  border-radius: var(--r-xs);
}

[hidden] {
  display: none !important;
}

hr {
  border: 0;
  border-top: 1px solid var(--c-line);
  margin: var(--sp-7) 0;
}

/* ---------- 排版 ---------- */

h1,
h2,
h3,
h4,
h5 {
  margin: 0;
  color: var(--c-ink);
  font-weight: 600;
  line-height: var(--lh-tight);
  text-wrap: balance;
}

h1 {
  font-family: var(--font-serif);
  font-size: var(--fs-h1);
  letter-spacing: var(--tracking-display);
  font-weight: 600;
}

h2 {
  font-family: var(--font-serif);
  font-size: var(--fs-h2);
  letter-spacing: var(--tracking-display);
}

h3 {
  font-size: var(--fs-h3);
  line-height: var(--lh-snug);
}

h4 {
  font-size: var(--fs-h4);
  line-height: var(--lh-snug);
}

p {
  margin: 0 0 var(--sp-4);
  color: var(--c-ink-2);
}

p:last-child {
  margin-bottom: 0;
}

strong {
  color: var(--c-ink);
  font-weight: 600;
}

small {
  font-size: var(--fs-sm);
}

code,
kbd,
samp {
  font-family: var(--font-mono);
  font-size: 0.9em;
  padding: 0.1em 0.4em;
  border-radius: var(--r-xs);
  background: var(--c-sand);
  color: var(--c-ink);
}

blockquote {
  margin: 0;
  padding-left: var(--sp-5);
  border-left: 2px solid var(--c-gold);
  font-family: var(--font-serif);
  font-size: var(--fs-lead);
  line-height: 1.9;
  color: var(--c-ink);
}

ul,
ol {
  margin: 0 0 var(--sp-4);
  padding-left: 1.25em;
  color: var(--c-ink-2);
}

li {
  margin-bottom: var(--sp-2);
}

li::marker {
  color: var(--c-gold-deep);
}

/* ---------- 版面骨架 ---------- */

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

.container-wide {
  max-width: var(--container-wide);
}

.container-narrow {
  max-width: var(--container-narrow);
}

.section {
  position: relative;
  padding-block: clamp(56px, 8vw, 112px);
}

.section--tight {
  padding-block: clamp(40px, 5vw, 72px);
}

.section--sand {
  background: var(--c-sand);
}

.section--paper-2 {
  background: var(--c-paper-2);
}

.section--line {
  border-top: 1px solid var(--c-line);
}

.section-head {
  max-width: 720px;
  margin-bottom: clamp(32px, 4.5vw, 64px);
}

.section-head h2 {
  margin-top: var(--sp-3);
}

.section-head p {
  margin-top: var(--sp-4);
  font-size: var(--fs-lead);
  line-height: 1.75;
}

.section-head--center {
  margin-inline: auto;
  text-align: center;
}

/* 通用网格 */
.grid {
  display: grid;
  gap: clamp(16px, 2vw, 28px);
}

.grid-2 {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.grid-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.grid-4 {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.split {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
  gap: clamp(32px, 5vw, 80px);
  align-items: center;
}

.split--top {
  align-items: start;
}

.stack > * + * {
  margin-top: var(--sp-4);
}

.stack-lg > * + * {
  margin-top: var(--sp-6);
}

.center {
  text-align: center;
}

.measure {
  max-width: var(--container-prose);
}

.muted {
  color: var(--c-ink-3);
}

.mono {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  letter-spacing: 0.02em;
}

.serif {
  font-family: var(--font-serif);
}

.nowrap {
  white-space: nowrap;
}

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

/* ---------- 跳转链接 ---------- */

.skip-link {
  position: fixed;
  top: -100px;
  left: var(--sp-4);
  z-index: 200;
  padding: 10px 18px;
  background: var(--c-ink);
  color: var(--c-paper);
  border-radius: var(--r-sm);
  font-size: var(--fs-sm);
  text-decoration: none;
  transition: top var(--dur-2) var(--ease-out);
}

.skip-link:focus-visible {
  top: var(--sp-4);
  color: var(--c-paper);
}

/* ---------- 页头 ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  background: color-mix(in srgb, var(--c-paper) 78%, transparent);
  -webkit-backdrop-filter: blur(16px) saturate(1.15);
  backdrop-filter: blur(16px) saturate(1.15);
  border-bottom: 1px solid transparent;
  transition: border-color var(--dur-2) var(--ease-out),
    background-color var(--dur-2) var(--ease-out);
}

.site-header.is-scrolled {
  background: color-mix(in srgb, var(--c-paper) 92%, transparent);
  border-bottom-color: var(--c-line);
}

.header-inner {
  display: flex;
  align-items: center;
  gap: clamp(16px, 3vw, 40px);
  min-height: 72px;
  padding-block: 10px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  color: var(--c-ink);
  text-decoration: none;
  flex-shrink: 0;
}

.brand:hover {
  color: var(--c-ink);
}

.brand-logo {
  display: block;
  height: 38px;
  width: auto;
  color: var(--c-ink);
}

@media (max-width: 620px) {
  .brand-logo {
    height: 31px;
  }
}

.brand-mark {
  width: 34px;
  height: 34px;
  color: var(--c-gold-deep);
  flex-shrink: 0;
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1;
}

.brand-name {
  font-family: var(--font-serif);
  font-size: 19px;
  font-weight: 600;
  letter-spacing: 0.03em;
}

.brand-sub {
  margin-top: 5px;
  font-family: var(--font-mono);
  font-size: 9.5px;
  letter-spacing: 0.22em;
  color: var(--c-ink-3);
  text-transform: uppercase;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: clamp(14px, 2vw, 30px);
  margin-left: auto;
}

.nav-link {
  position: relative;
  padding: 8px 2px;
  font-size: 14px;
  color: var(--c-ink-2);
  text-decoration: none;
  white-space: nowrap;
}

.nav-link::after {
  content: "";
  position: absolute;
  left: 2px;
  right: 2px;
  bottom: 2px;
  height: 1.5px;
  background: var(--c-gold);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--dur-2) var(--ease-out);
}

.nav-link:hover {
  color: var(--c-ink);
}

.nav-link:hover::after,
.nav-link[aria-current="page"]::after {
  transform: scaleX(1);
}

.nav-link[aria-current="page"] {
  color: var(--c-ink);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  margin-left: var(--sp-2);
}

.nav-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  margin-left: auto;
  border: 1px solid var(--c-line-2);
  border-radius: var(--r-full);
  color: var(--c-ink);
}

.nav-toggle-bars {
  position: relative;
  width: 18px;
  height: 12px;
}

.nav-toggle-bars span {
  position: absolute;
  left: 0;
  right: 0;
  height: 1.5px;
  background: currentColor;
  transition: transform var(--dur-2) var(--ease-out), opacity var(--dur-1),
    top var(--dur-2) var(--ease-out);
}

.nav-toggle-bars span:nth-child(1) {
  top: 0;
}
.nav-toggle-bars span:nth-child(2) {
  top: 5px;
}
.nav-toggle-bars span:nth-child(3) {
  top: 10px;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bars span:nth-child(1) {
  top: 5px;
  transform: rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bars span:nth-child(2) {
  opacity: 0;
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bars span:nth-child(3) {
  top: 5px;
  transform: rotate(-45deg);
}

/* 移动端菜单 */
.mobile-menu {
  position: fixed;
  inset: 0;
  z-index: var(--z-menu);
  display: flex;
  flex-direction: column;
  padding: calc(72px + var(--sp-6)) var(--gutter) var(--sp-7);
  background: var(--c-paper);
  overflow-y: auto;
}

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

.mobile-nav {
  display: flex;
  flex-direction: column;
  gap: 2px;
  margin-bottom: var(--sp-6);
}

.mobile-nav a {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  padding: 16px 0;
  border-bottom: 1px solid var(--c-line);
  font-family: var(--font-serif);
  font-size: 24px;
  color: var(--c-ink);
  text-decoration: none;
}

.mobile-nav a span {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--c-ink-3);
  letter-spacing: 0.1em;
}

.mobile-menu .btn {
  width: 100%;
}

.mobile-menu-foot {
  margin-top: auto;
  padding-top: var(--sp-6);
  font-size: var(--fs-sm);
  color: var(--c-ink-3);
}

/* ---------- 页脚 ---------- */

.site-footer {
  position: relative;
  z-index: 1;
  background: var(--c-sand);
  color: var(--c-ink-2);
  border-top: 1px solid var(--c-line);
}

.footer-top {
  display: grid;
  grid-template-columns: minmax(0, 1.6fr) repeat(3, minmax(0, 1fr));
  gap: clamp(32px, 5vw, 72px);
  padding-block: clamp(48px, 6vw, 80px);
}

.footer-brand .brand {
  margin-bottom: var(--sp-5);
}

.footer-brand p {
  max-width: 34ch;
  font-size: var(--fs-sm);
  line-height: 1.8;
  color: var(--c-ink-2);
}

.footer-title {
  margin: 0 0 var(--sp-4);
  font-family: var(--font-mono);
  font-size: 10.5px;
  font-weight: 500;
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
  color: var(--c-ink-3);
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-links a {
  font-size: var(--fs-sm);
  color: var(--c-ink-2);
  text-decoration: none;
}

.footer-links a:hover {
  color: var(--c-gold-deep);
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-4) var(--sp-6);
  align-items: flex-start;
  justify-content: space-between;
  padding-block: var(--sp-5);
  border-top: 1px solid var(--c-line-2);
  font-size: var(--fs-xs);
  line-height: 1.8;
  color: var(--c-ink-3);
}

.footer-bottom p {
  margin: 0;
  color: inherit;
  font-size: inherit;
}

.footer-legal {
  max-width: 78ch;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.footer-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 6px var(--sp-4);
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--c-ink-3);
}

.footer-meta a {
  color: inherit;
}

/* ---------- 响应式 ---------- */

@media (max-width: 1080px) {
  .site-nav {
    gap: 16px;
  }
  .header-actions .btn--ghost {
    display: none;
  }
  .footer-top {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .footer-brand {
    grid-column: 1 / -1;
  }
}

@media (max-width: 860px) {
  .site-nav,
  .header-actions {
    display: none;
  }
  .nav-toggle {
    display: inline-flex;
  }
  .header-inner {
    min-height: 64px;
  }
  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .split {
    grid-template-columns: minmax(0, 1fr);
    gap: var(--sp-7);
  }
}

@media (max-width: 620px) {
  :root {
    --fs-body: 15.5px;
    --lh-body: 1.75;
  }
  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: minmax(0, 1fr);
  }
  .footer-top {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .footer-brand {
    grid-column: 1 / -1;
  }
  .footer-bottom {
    flex-direction: column;
  }
}

@media (max-width: 380px) {
  :root {
    --gutter: 18px;
  }
  .brand-sub {
    display: none;
  }
}

/* ---------- 打印 ---------- */

@media print {
  body::after,
  .site-header,
  .site-footer,
  .nav-toggle,
  .mobile-menu,
  .no-print {
    display: none !important;
  }
  body {
    background: #fff;
    color: #000;
  }
  a {
    color: #000;
    text-decoration: underline;
  }
}