/* ==========================================================================
   壹号官网 / yihao-pathfinder.com.cn — 共享站点层
   0. 重置  1. 变量  2. 基础排版  3. 通用组件  4. 头部轨道
   5. 页脚  6. 响应式  7. 减少动效
   ========================================================================== */

/* ---------- 0. 重置 ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body, h1, h2, h3, h4, h5, p, ul, ol, dl, dd, figure, blockquote, fieldset { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; }
button { font: inherit; color: inherit; background: none; border: 0; }
a { color: inherit; text-decoration: none; }
table { border-collapse: collapse; }
[id="main-content"] { scroll-margin-top: 5.5rem; }
:where(a, button, [tabindex], summary):focus-visible {
  outline: 2px solid #F0B23F;
  outline-offset: 3px;
  border-radius: 1px;
}

/* ---------- 1. 变量 ---------- */
:root {
  --ink-950: #06101B;
  --ink-900: #0B1A29;
  --ink-800: #142B3F;
  --paper: #F5F1E8;
  --paper-dim: #CFC7B8;
  --amber: #F0B23F;
  --amber-deep: #8F5B0A;
  --celadon: #72B3A0;
  --celadon-deep: #2C6B5B;
  --clay: #C96A4A;

  --rail-width: 288px;
  --content-max: 1440px;
  --gutter: clamp(1.15rem, 3.4vw, 3.5rem);

  --line: rgba(245, 241, 232, 0.16);
  --line-strong: rgba(245, 241, 232, 0.34);

  --font-sans: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  --font-mono: "IBM Plex Mono", "Noto Sans Mono CJK SC", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;

  --shadow-stamp: 10px 10px 0 rgba(3, 9, 16, 0.9);
  --shadow-stamp-sm: 5px 5px 0 rgba(3, 9, 16, 0.8);
  --ease: cubic-bezier(0.2, 0.8, 0.2, 1);
  --cut-corner: polygon(0 0, 100% 0, 100% calc(100% - 14px), calc(100% - 14px) 100%, 0 100%);
}

/* ---------- 2. 基础排版 ---------- */
body {
  min-height: 100vh;
  font-family: var(--font-sans);
  font-size: clamp(16px, 0.55vw + 14.6px, 17.5px);
  font-weight: 400;
  line-height: 1.85;
  color: var(--paper);
  background-color: var(--ink-950);
  background-image:
    radial-gradient(circle at 84% -12%, rgba(114, 179, 160, 0.12), transparent 56%),
    radial-gradient(circle at 12% 108%, rgba(240, 178, 63, 0.09), transparent 52%),
    repeating-linear-gradient(0deg, rgba(245, 241, 232, 0.03) 0 1px, transparent 1px 92px);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4 { font-weight: 300; line-height: 1.08; letter-spacing: -0.02em; }
p { text-wrap: pretty; }
strong, b { font-weight: 700; }
code, kbd, samp { font-family: var(--font-mono); font-size: 0.9em; }
::selection { background: var(--amber); color: var(--ink-950); }

.display-title {
  font-size: clamp(2.8rem, 6.6vw, 6rem);
  font-weight: 300;
  line-height: 0.94;
  letter-spacing: -0.04em;
}
.section-title {
  font-size: clamp(1.6rem, 2.8vw, 2.4rem);
  font-weight: 300;
  letter-spacing: -0.015em;
}

/* ---------- 3. 通用组件 ---------- */
.skip-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 400;
  padding: 0.7rem 1.05rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  font-weight: 700;
  color: var(--ink-950);
  background: var(--amber);
  border: 2px solid var(--ink-950);
  box-shadow: var(--shadow-stamp-sm);
  transform: translateY(-180%);
  transition: transform 0.2s var(--ease);
}
.skip-link:focus { transform: translateY(0); }

/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  padding: 0.9rem 1.35rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  line-height: 1.25;
  color: var(--paper);
  background: transparent;
  border: 1px solid var(--line-strong);
  cursor: pointer;
  transition: transform 0.22s var(--ease), box-shadow 0.22s var(--ease),
              background-color 0.22s var(--ease), color 0.22s var(--ease),
              border-color 0.22s var(--ease);
}
.btn:hover { transform: translateY(-2px); box-shadow: var(--shadow-stamp-sm); }
.btn--primary {
  color: var(--ink-950);
  background: var(--amber);
  border-color: var(--amber);
  font-weight: 700;
}
.btn--primary:hover { background: #FFC65A; }
.btn--celadon {
  color: var(--ink-950);
  background: var(--celadon);
  border-color: var(--celadon);
  font-weight: 700;
}
.btn--celadon:hover { background: #8AC7B6; }
.btn--ghost:hover { border-color: var(--amber); color: var(--amber); }

/* 面包屑 */
.breadcrumbs {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  letter-spacing: 0.14em;
  color: var(--paper-dim);
}
.breadcrumbs ol { display: flex; flex-wrap: wrap; align-items: center; gap: 0.45rem; }
.breadcrumbs li { display: inline-flex; align-items: center; }
.breadcrumbs li + li::before { content: "/"; margin-right: 0.45rem; color: var(--line-strong); }
.breadcrumbs a { color: var(--paper-dim); border-bottom: 1px solid transparent; }
.breadcrumbs a:hover { color: var(--paper); border-bottom-color: var(--amber); }

/* 编辑部章节标记 */
.section-marker {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  margin-bottom: 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.66rem;
  letter-spacing: 0.2em;
  color: var(--paper-dim);
}
.section-marker::after { content: ""; flex: 1 1 auto; height: 1px; background: var(--line-strong); }
.section-marker-num { color: var(--amber); letter-spacing: 0.1em; font-weight: 700; }

/* 索引标签 */
.index-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.26rem 0.55rem;
  font-family: var(--font-mono);
  font-size: 0.63rem;
  letter-spacing: 0.16em;
  color: var(--paper-dim);
  border: 1px solid var(--line-strong);
}
.index-tag--amber { color: var(--amber); border-color: rgba(240, 178, 63, 0.55); }
.index-tag--celadon { color: var(--celadon); border-color: rgba(114, 179, 160, 0.55); }

/* 正文阅读区 */
.prose {
  max-width: 68ch;
  font-size: 1.02rem;
  line-height: 1.95;
}
.prose > * + * { margin-top: 1.3em; }
.prose h2 {
  margin-top: 2.1em;
  font-size: clamp(1.45rem, 2.3vw, 1.95rem);
  font-weight: 300;
  letter-spacing: -0.01em;
}
.prose h3 { font-size: 1.12rem; font-weight: 700; line-height: 1.5; }
.prose ul, .prose ol { padding-left: 1.35em; list-style: disc; }
.prose ol { list-style: decimal; }
.prose li + li { margin-top: 0.5em; }
.prose a { color: var(--amber); border-bottom: 1px solid rgba(240, 178, 63, 0.45); }
.prose a:hover { border-bottom-color: var(--amber); }
.prose blockquote {
  padding-left: 1.1rem;
  border-left: 3px solid var(--celadon);
  color: var(--paper-dim);
}
.prose hr { height: 0; border: 0; border-top: 1px solid var(--line-strong); }

/* 12 列网格 */
.grid-12 { display: grid; grid-template-columns: repeat(12, minmax(0, 1fr)); gap: clamp(1rem, 2vw, 1.75rem); }
.span-4 { grid-column: span 4; }
.span-6 { grid-column: span 6; }
.span-8 { grid-column: span 8; }
.span-12 { grid-column: span 12; }

/* 图片容器基础规则（页面阶段放入 <img> 占位） */
.media-frame {
  display: grid;
  grid-template-rows: 1fr auto;
  margin: 0;
  background: var(--ink-900);
  border: 1px solid var(--line-strong);
  box-shadow: var(--shadow-stamp);
  overflow: hidden;
}
.media-frame img {
  width: 100%;
  height: 100%;
  min-height: 0;
  object-fit: cover;
}
.media-frame figcaption {
  padding: 0.55rem 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.63rem;
  letter-spacing: 0.12em;
  color: var(--paper-dim);
  background: var(--ink-900);
  border-top: 1px solid var(--line);
}
.media-frame--wide { aspect-ratio: 16 / 9; }
.media-frame--tall { aspect-ratio: 3 / 4; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame--cut {
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 22px), calc(100% - 22px) 100%, 0 100%);
}

/* 滚动显现协议 */
.has-js [data-reveal] {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.48s var(--ease), transform 0.48s var(--ease);
  transition-delay: calc(var(--reveal-i, 0) * 70ms);
}
.has-js [data-reveal].is-revealed { opacity: 1; transform: none; }

/* ---------- 4. 头部：侧边轨道 ---------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 60;
  display: grid;
  grid-template-rows: auto 1fr auto;
  width: var(--rail-width);
  padding: 1.7rem 1.5rem 1.5rem;
  overflow-y: auto;
  overscroll-behavior: contain;
  background:
    linear-gradient(180deg, #081524 0%, var(--ink-950) 58%, #081826 100%);
  border-right: 1px solid var(--line-strong);
}
.site-header::after {
  content: "";
  position: absolute;
  top: 0;
  right: -1px;
  width: 4px;
  height: 30vh;
  background: linear-gradient(180deg, var(--amber), rgba(240, 178, 63, 0));
  pointer-events: none;
}

.rail-brand { min-width: 0; }
.brand-lockup {
  display: flex;
  align-items: flex-start;
  gap: 0.7rem;
  color: var(--paper);
}
.brand-mark {
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  width: 2.55rem;
  height: 2.55rem;
  font-family: var(--font-mono);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--ink-950);
  background: var(--amber);
  clip-path: var(--cut-corner);
  transition: background-color 0.2s var(--ease);
}
.brand-lockup:hover .brand-mark { background: #FFC65A; }
.brand-text { display: block; min-width: 0; }
.brand-name {
  display: block;
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  line-height: 1.3;
}
.brand-latin {
  display: block;
  margin-top: 0.22rem;
  font-family: var(--font-mono);
  font-size: 0.58rem;
  letter-spacing: 0.2em;
  color: var(--paper-dim);
}
.brand-descriptor {
  margin-top: 1rem;
  padding-left: 0.62rem;
  font-size: 0.76rem;
  line-height: 1.65;
  color: var(--paper-dim);
  border-left: 2px solid var(--celadon);
}

/* 移动抽屉开关（桌面隐藏） */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 0.55rem;
  padding: 0.55rem 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.64rem;
  letter-spacing: 0.14em;
  color: var(--paper);
  background: transparent;
  border: 1px solid var(--line-strong);
  cursor: pointer;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}
.nav-toggle:hover { border-color: var(--amber); color: var(--amber); }
.nav-toggle-bars { display: grid; gap: 4px; width: 14px; }
.nav-toggle-bars span {
  display: block;
  height: 2px;
  background: currentColor;
  transition: transform 0.22s var(--ease);
}
.site-header[data-open] .nav-toggle { border-color: var(--amber); color: var(--amber); }
.site-header[data-open] .nav-toggle-bars span:first-child { transform: translateY(3px) rotate(45deg); }
.site-header[data-open] .nav-toggle-bars span:last-child { transform: translateY(-3px) rotate(-45deg); }
.nav-toggle-label { display: block; white-space: nowrap; }

/* 主导航 */
.primary-nav {
  display: flex;
  flex-direction: column;
  min-height: 0;
  margin-top: 2rem;
}
.nav-caption {
  padding-bottom: 0.65rem;
  font-family: var(--font-mono);
  font-size: 0.6rem;
  letter-spacing: 0.22em;
  color: var(--paper-dim);
  border-bottom: 1px solid var(--line);
}
.nav-list { display: block; }
.nav-item { display: block; }
.nav-link {
  display: grid;
  grid-template-columns: 2.1rem 1fr;
  align-items: center;
  gap: 0.35rem;
  padding: 0.6rem 0.5rem 0.6rem 0.55rem;
  margin-left: -0.55rem;
  font-size: 0.94rem;
  line-height: 1.4;
  color: var(--paper);
  border-bottom: 1px solid var(--line);
  border-left: 3px solid transparent;
  transition: color 0.2s var(--ease), background-color 0.2s var(--ease),
              border-color 0.2s var(--ease), transform 0.2s var(--ease);
}
.nav-index {
  font-family: var(--font-mono);
  font-size: 0.63rem;
  letter-spacing: 0.1em;
  color: var(--paper-dim);
  transition: color 0.2s var(--ease);
}
.nav-label { display: block; }
.nav-link:hover {
  color: var(--amber);
  border-left-color: var(--amber);
  background: rgba(240, 178, 63, 0.07);
  transform: translateX(2px);
}
.nav-link:hover .nav-index { color: var(--amber); }
.nav-link[aria-current="page"] {
  color: var(--amber);
  font-weight: 700;
  background: rgba(240, 178, 63, 0.13);
  border-left-color: var(--amber);
}
.nav-link[aria-current="page"] .nav-index { color: var(--amber); font-weight: 700; }

.nav-progress {
  position: relative;
  height: 3px;
  margin-top: 1.25rem;
  background: var(--line);
  overflow: hidden;
}
.nav-progress-fill {
  display: block;
  width: 0%;
  height: 100%;
  background: var(--celadon);
  transition: width 0.18s linear;
}

/* 轨道工具区 */
.rail-utility {
  display: block;
  margin-top: 1.6rem;
  padding-top: 1rem;
  border-top: 1px solid var(--line);
}
.update-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.3rem 0.55rem;
  font-family: var(--font-mono);
  font-size: 0.6rem;
  letter-spacing: 0.14em;
  color: var(--celadon);
  border: 1px solid rgba(114, 179, 160, 0.45);
}
.update-badge::before {
  content: "";
  width: 6px;
  height: 6px;
  background: var(--celadon);
  flex: 0 0 auto;
}
.utility-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.3rem 1.1rem;
  margin-top: 0.9rem;
}
.utility-link {
  font-size: 0.76rem;
  color: var(--paper-dim);
  border-bottom: 1px solid transparent;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}
.utility-link:hover { color: var(--paper); border-bottom-color: var(--amber); }

/* ---------- 5. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: clamp(3rem, 7vw, 7rem);
  background: var(--ink-900);
  border-top: 1px solid var(--line-strong);
}
.site-footer::before {
  content: "";
  position: absolute;
  top: -1px;
  left: 0;
  right: 0;
  height: 4px;
  background: repeating-linear-gradient(90deg, var(--amber) 0 26px, transparent 26px 48px);
}
.footer-inner {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: clamp(2.4rem, 5vw, 4.5rem) var(--gutter) 1.75rem;
}
.footer-eyebrow {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.2em;
  color: var(--paper-dim);
}
.footer-eyebrow::after { content: ""; flex: 1 1 auto; height: 1px; background: var(--line-strong); }
.footer-eyebrow-num { color: var(--amber); font-weight: 700; }

.footer-top {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
  gap: clamp(1.75rem, 4vw, 4.5rem);
  margin-top: clamp(1.75rem, 3vw, 2.75rem);
}
.footer-lead { min-width: 0; }
.footer-brand-line {
  max-width: 22ch;
  font-size: clamp(1.3rem, 2.5vw, 2rem);
  font-weight: 300;
  line-height: 1.28;
  letter-spacing: -0.01em;
}
.footer-summary {
  max-width: 46ch;
  margin-top: 1rem;
  font-size: 0.94rem;
  line-height: 1.85;
  color: var(--paper-dim);
}
.footer-rhythm {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin-top: 1.1rem;
  padding: 0.32rem 0.6rem;
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.14em;
  color: var(--celadon);
  border: 1px solid rgba(114, 179, 160, 0.4);
}

.footer-contact {
  min-width: 0;
  padding-left: clamp(1rem, 2vw, 1.5rem);
  border-left: 2px solid var(--amber);
}
.footer-heading {
  margin-bottom: 0.9rem;
  font-family: var(--font-mono);
  font-size: 0.63rem;
  font-weight: 400;
  letter-spacing: 0.2em;
  line-height: 1.4;
  color: var(--paper-dim);
}
.contact-list { display: grid; gap: 0.6rem; }
.contact-row {
  display: grid;
  grid-template-columns: 4.9rem minmax(0, 1fr);
  gap: 0.55rem;
  align-items: baseline;
}
.contact-row dt {
  font-family: var(--font-mono);
  font-size: 0.6rem;
  letter-spacing: 0.12em;
  color: var(--paper-dim);
}
.contact-row dd { min-width: 0; font-size: 0.9rem; line-height: 1.7; overflow-wrap: anywhere; }
.contact-value { font-weight: 700; }
.contact-note {
  max-width: 44ch;
  margin-top: 0.9rem;
  font-size: 0.76rem;
  line-height: 1.75;
  color: var(--paper-dim);
}

.footer-columns {
  display: grid;
  grid-template-columns: 1.1fr 1fr 0.9fr;
  gap: clamp(1.25rem, 3vw, 3rem);
  margin-top: clamp(2.1rem, 4vw, 3.4rem);
  padding-top: clamp(1.4rem, 3vw, 2rem);
  border-top: 1px solid var(--line);
}
.footer-column { min-width: 0; }
.footer-list { display: grid; gap: 0.5rem; }
.footer-link {
  display: inline-block;
  padding-bottom: 1px;
  font-size: 0.92rem;
  color: var(--paper);
  border-bottom: 1px solid transparent;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}
.footer-link:hover { color: var(--amber); border-bottom-color: var(--amber); }

.footer-wordmark {
  margin-top: clamp(1.8rem, 4vw, 3rem);
  font-family: var(--font-sans);
  font-size: clamp(2.4rem, 11vw, 8rem);
  font-weight: 300;
  line-height: 0.84;
  letter-spacing: -0.045em;
  color: transparent;
  -webkit-text-stroke: 1px rgba(245, 241, 232, 0.15);
  user-select: none;
  overflow: hidden;
}
@supports not (-webkit-text-stroke: 1px #000) {
  .footer-wordmark { color: rgba(245, 241, 232, 0.07); }
}

.footer-base {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.7rem 1.5rem;
  margin-top: clamp(1.5rem, 3vw, 2.2rem);
  padding-top: 1.1rem;
  border-top: 1px solid var(--line);
}
.footer-legal,
.footer-copy {
  font-family: var(--font-mono);
  font-size: 0.63rem;
  letter-spacing: 0.12em;
  color: var(--paper-dim);
}
.to-top {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin-left: auto;
  padding: 0.48rem 0.8rem;
  font-family: var(--font-mono);
  font-size: 0.63rem;
  letter-spacing: 0.14em;
  color: var(--paper);
  border: 1px solid var(--line-strong);
  cursor: pointer;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease), transform 0.2s var(--ease);
}
.to-top:hover { color: var(--amber); border-color: var(--amber); transform: translateY(-2px); }
.to-top-arrow { display: block; font-size: 0.8rem; line-height: 1; }

/* ---------- 6. 响应式 ---------- */
@media (min-width: 1024px) {
  body { padding-left: var(--rail-width); }
}

@media (max-width: 900px) {
  .grid-12 > .span-4,
  .grid-12 > .span-6,
  .grid-12 > .span-8 { grid-column: span 12; }
  .footer-top { grid-template-columns: minmax(0, 1fr); }
  .footer-contact {
    padding-left: 0;
    padding-top: 1.25rem;
    border-left: 0;
    border-top: 2px solid var(--amber);
  }
}

@media (max-width: 1023.98px) {
  .site-header {
    position: sticky;
    top: 0;
    bottom: auto;
    left: auto;
    width: 100%;
    max-height: 100vh;
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: center;
    padding: 0.8rem var(--gutter);
    background: rgba(6, 16, 27, 0.97);
    border-right: 0;
    border-bottom: 1px solid var(--line-strong);
  }
  .site-header::after { display: none; }
  .brand-mark { width: 2.1rem; height: 2.1rem; font-size: 1rem; }
  .brand-name { font-size: 0.95rem; }
  .brand-latin { font-size: 0.54rem; letter-spacing: 0.16em; }
  .brand-descriptor { display: none; }
  .nav-toggle { display: inline-flex; }
  .primary-nav {
    grid-column: 1 / -1;
    display: none;
    margin-top: 0.9rem;
    padding-top: 0.9rem;
    border-top: 1px solid var(--line);
  }
  .site-header[data-open] .primary-nav { display: flex; }
  .nav-link { padding: 0.72rem 0.5rem 0.72rem 0.55rem; font-size: 1rem; }
  .nav-progress { margin-top: 1rem; }
  .rail-utility {
    grid-column: 1 / -1;
    display: none;
    margin-top: 1.1rem;
    padding-top: 0.9rem;
  }
  .site-header[data-open] .rail-utility { display: block; }
  .footer-wordmark { -webkit-text-stroke-width: 1px; }
}

@media (max-width: 760px) {
  .footer-columns { grid-template-columns: 1fr 1fr; }
  .contact-row { grid-template-columns: 4.2rem minmax(0, 1fr); }
}

@media (max-width: 520px) {
  .footer-columns { grid-template-columns: 1fr; }
  .footer-base .to-top { margin-left: 0; }
  .btn { width: 100%; }
}

/* ---------- 7. 减少动效 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    transition-delay: 0ms !important;
  }
  .has-js [data-reveal] { opacity: 1; transform: none; }
  .skip-link { transition: none; }
  .btn:hover, .to-top:hover, .nav-link:hover { transform: none; }
}