/* 全站布局：负责纸面基底、排版、顶栏、内容带、页脚与公共断点。 */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  width: 100%;
  min-width: 0;
  overflow-x: clip;
  scroll-behavior: smooth;
  scrollbar-color: var(--line-soft) var(--paper);
}

body {
  width: 100%;
  min-height: 100vh;
  margin: 0;
  overflow-x: clip;
  background-color: var(--paper);
  background-image:
    linear-gradient(90deg, rgb(16 17 18 / 2.4%) 1px, transparent 1px),
    linear-gradient(rgb(16 17 18 / 2.4%) 1px, transparent 1px);
  background-size: 28px 28px;
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 15px;
  line-height: 1.65;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

body,
button,
input,
select,
textarea {
  font-family: var(--font-sans);
}

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

a {
  color: inherit;
}

button,
input,
select,
textarea {
  min-width: 0;
  font-size: inherit;
}

button,
a,
summary {
  -webkit-tap-highlight-color: transparent;
}

h1,
h2,
h3,
h4,
p {
  margin-top: 0;
}

h1,
h2,
h3,
h4 {
  color: var(--ink);
  line-height: 1.12;
  overflow-wrap: anywhere;
  text-wrap: balance;
}

h1 {
  margin-bottom: var(--space-4);
  font-size: clamp(2.6rem, 5vw, 4.4rem);
  font-weight: 850;
  letter-spacing: -0.045em;
}

h2 {
  margin-bottom: var(--space-3);
  font-size: clamp(1.75rem, 3vw, 2.55rem);
  font-weight: 820;
  letter-spacing: -0.035em;
}

h3 {
  margin-bottom: var(--space-2);
  font-size: 1.04rem;
  font-weight: 760;
}

h4 {
  margin-bottom: var(--space-2);
  font-size: 0.98rem;
  font-weight: 740;
}

p {
  margin-bottom: var(--space-4);
}

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

:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 3px;
  box-shadow: 0 0 0 2px var(--focus-gap), 0 0 0 5px var(--focus-ring);
}

.container {
  width: min(calc(100% - 40px), var(--content-width));
  min-width: 0;
  margin-inline: auto;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: var(--space-3);
  left: var(--space-3);
  padding: 9px 13px;
  transform: translateY(-180%);
  border: 1px solid var(--inverse-ink);
  background: var(--inverse);
  color: var(--inverse-ink);
}

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

.page-progress {
  position: fixed;
  z-index: 90;
  top: 0;
  right: 0;
  left: 0;
  height: 3px;
  transform: scaleX(0);
  transform-origin: left;
  background: var(--accent);
  opacity: 0;
}

.page-progress.htmx-request {
  transform: scaleX(0.72);
  opacity: 1;
  transition: transform 700ms ease, opacity 160ms ease;
}

.site-header {
  position: sticky;
  z-index: 40;
  top: 0;
  border-bottom: 1px solid var(--line-strong);
  background: var(--paper-raised);
}

.header-inner {
  display: flex;
  min-width: 0;
  min-height: var(--header-height);
  align-items: center;
  gap: 20px;
}

.header-inner::before,
.header-inner::after {
  position: absolute;
  top: 50%;
  width: 12px;
  height: 1px;
  background: var(--accent);
  content: "";
}

.header-inner::before {
  left: max(4px, calc((100vw - var(--content-width)) / 2 - 24px));
}

.header-inner::after {
  right: max(4px, calc((100vw - var(--content-width)) / 2 - 24px));
}

.header-navigation {
  display: flex;
  min-width: 0;
  flex: 1;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}

.site-nav,
.utility-nav {
  display: flex;
  min-width: 0;
  align-items: center;
  gap: var(--space-1);
}

.menu-button {
  display: none;
}

.content-band {
  padding-block: var(--space-9);
  border-bottom: 1px solid var(--line-strong);
  background: var(--paper);
}

.content-band:nth-of-type(even) {
  background: var(--paper-alt);
}

.section-layout {
  display: grid;
  min-width: 0;
  grid-template-columns: minmax(220px, 0.72fr) minmax(0, 1.8fr);
  gap: var(--space-8);
  align-items: start;
}

.section-heading {
  min-width: 0;
  max-width: 560px;
}

.section-heading p {
  margin-bottom: 0;
  color: var(--ink-soft);
}

.site-footer {
  border-top: 1px solid var(--line-strong);
  background: var(--paper-alt);
  color: var(--ink-soft);
}

.footer-inner {
  display: grid;
  min-width: 0;
  grid-template-columns: minmax(260px, 1.5fr) auto;
  gap: var(--space-6) var(--space-8);
  align-items: center;
  padding-block: var(--space-7);
}

.footer-brand {
  display: flex;
  min-width: 0;
  align-items: center;
  gap: var(--space-3);
}

.footer-brand p,
.footer-note {
  margin: 2px 0 0;
  color: var(--ink-muted);
  font-size: 0.86rem;
}

.footer-brand .footer-motto {
  margin-top: 7px;
  color: var(--ink-soft);
  font-size: 0.74rem;
  letter-spacing: 0.1em;
  line-height: 1.5;
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: var(--space-5);
}

.footer-nav a {
  color: var(--ink-soft);
  font-size: 0.88rem;
  text-decoration: none;
  text-underline-offset: 3px;
}

.footer-nav a:hover {
  color: var(--accent-text);
  text-decoration: underline;
}

.footer-note {
  grid-column: 1 / -1;
  padding-top: var(--space-4);
  border-top: 1px solid var(--line);
}

@media (max-width: 1200px) {
  .header-inner::before,
  .header-inner::after {
    display: none;
  }

  .js .menu-button {
    display: inline-flex;
    margin-left: auto;
  }

  .header-navigation {
    position: absolute;
    z-index: 2;
    top: calc(100% + 1px);
    right: 0;
    left: 0;
    display: grid;
    max-height: calc(100dvh - var(--header-height) - 1px);
    padding: var(--space-3) 20px var(--space-4);
    overflow-y: auto;
    border-bottom: 1px solid var(--line-strong);
    background: var(--paper-raised);
  }

  .js .header-navigation {
    display: none;
  }

  .js .header-navigation[data-open="true"] {
    display: grid;
  }

  .site-nav,
  .utility-nav {
    align-items: stretch;
  }

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

  .utility-nav {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    justify-content: flex-end;
    padding-top: var(--space-3);
    border-top: 1px solid var(--line);
  }

  .utility-nav > * {
    width: 100%;
    min-height: 44px;
  }
}

@media (max-width: 960px) {
  .section-layout {
    grid-template-columns: 1fr;
    gap: var(--space-6);
  }
}

@media (max-width: 560px) {
  .utility-nav {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 720px) {
  .container {
    width: min(calc(100% - 28px), var(--content-width));
  }

  .content-band {
    padding-block: var(--space-7);
  }

  .footer-inner {
    grid-template-columns: 1fr;
  }

  .footer-nav {
    justify-content: flex-start;
    gap: var(--space-3) var(--space-5);
  }
}

@media (max-width: 420px) {
  .container {
    width: min(calc(100% - 20px), var(--content-width));
  }

  .header-navigation {
    padding-inline: 10px;
  }

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

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

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

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}