:root {
  --night-base: #0a0a0a;
  --night-card: #141414;
  --night-card-sub: #1f1f1f;
  --night-card-hover: #262626;
  --white-main: #f4f1ea;
  --white-muted: #9e9a91;
  --border-dark: #292929;
  --border-focus: #444444;
  --font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Courier New", monospace;
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 10px;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  background-color: var(--night-base);
  color: var(--white-main);
  font-family: var(--font-family);
  font-size: 16px;
  line-height: 1.75;
}

body {
  background-color: var(--night-base);
  color: var(--white-main);
  min-height: 100vh;
  overflow-x: clip;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-dark);
}

a {
  color: inherit;
  text-decoration: none;
  transition: opacity 0.2s ease, background-color 0.2s ease, color 0.2s ease;
}

.wrap {
  width: min(1100px, calc(100% - 40px));
  margin: 0 auto;
}

/* ================= 顶栏 Header ================= */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(10, 10, 10, 0.96);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border-dark);
}

.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  padding: 14px 0 6px;
}

.brand-link {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 15px;
  font-weight: 800;
  letter-spacing: 0.1em;
  color: var(--white-main);
}

.char-icon {
  width: 18px;
  height: 18px;
  background-color: var(--white-main);
  color: var(--night-base);
  font-size: 11px;
  font-weight: 900;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 2px;
  flex-shrink: 0;
  line-height: 1;
}

.nav-links {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 18px;
  align-items: center;
}

.nav-links a {
  font-size: 14px;
  color: var(--white-muted);
  min-height: 40px;
  display: inline-flex;
  align-items: center;
  padding: 0 4px;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--white-main);
  font-weight: 700;
}

/* 页眉极小字条目 */
.header-keywords {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 14px;
  padding: 4px 0 10px;
  border-top: 1px solid rgba(41, 41, 41, 0.8);
}

.header-keywords a,
.header-keywords span {
  font-size: 11px;
  font-family: var(--font-mono);
  color: var(--white-muted);
  letter-spacing: 0.03em;
  opacity: 0.85;
}

.header-keywords a:hover {
  opacity: 1;
  color: var(--white-main);
}

/* ================= 英雄区 Hero ================= */
.hero-section {
  padding: 56px 0 48px;
  border-bottom: 1px solid var(--border-dark);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 40px;
  align-items: center;
}

.hero-content h1 {
  font-size: 38px;
  font-weight: 900;
  line-height: 1.25;
  letter-spacing: 0.02em;
  color: var(--white-main);
  margin-bottom: 14px;
}

.hero-content h1 .sub-heading {
  display: block;
  font-size: 20px;
  font-weight: 500;
  color: var(--white-muted);
  margin-top: 8px;
  letter-spacing: 0.04em;
}

.hero-lead {
  font-size: 16px;
  line-height: 1.8;
  color: #d1cdc4;
  margin-bottom: 24px;
  max-width: 540px;
}

.btn-group {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-bottom: 22px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 0 22px;
  font-size: 14px;
  font-weight: 700;
  border-radius: var(--radius-sm);
  background-color: var(--white-main);
  color: var(--night-base);
  border: 1px solid var(--white-main);
  cursor: pointer;
}

.btn:hover {
  background-color: #ffffff;
  border-color: #ffffff;
}

.btn.btn-outline {
  background-color: transparent;
  color: var(--white-main);
  border: 1px solid var(--border-focus);
}

.btn.btn-outline:hover {
  background-color: var(--night-card);
  border-color: var(--white-main);
}

.capsule-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 12px;
  margin-bottom: 16px;
}

.pill-item {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  font-family: var(--font-mono);
  color: var(--white-main);
  background-color: var(--night-card);
  padding: 4px 10px;
  border-radius: 2px;
  border: 1px solid var(--border-dark);
}

.update-date {
  font-size: 12px;
  color: var(--white-muted);
  font-family: var(--font-mono);
}

/* ================= 反白单字专属视觉卡片 ================= */
/* 规范：满版黑#0A0A0A，只有一个反白的字#F4F1EA，字居中，四周黑边不等，字内极小的完整词#0A0A0A，无点缀色，小词装进笔画里 */
.reverse-char-card {
  width: 100%;
  height: 320px;
  background-color: #0a0a0a;
  border: 1px solid var(--border-dark);
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  padding-top: 35px; /* 上黑边 */
  padding-bottom: 15px; /* 下黑边不等 */
  padding-left: 20px; /* 左黑边 */
  padding-right: 40px; /* 右黑边不等 */
  box-shadow: inset 0 0 40px rgba(0, 0, 0, 0.8);
}

.giant-reversed-glyph {
  position: relative;
  font-size: 168px;
  font-weight: 900;
  line-height: 1;
  color: #f4f1ea;
  font-family: "Noto Serif SC", "Songti SC", "PingFang SC", "Microsoft YaHei", serif;
  user-select: none;
  display: inline-block;
  letter-spacing: -0.05em;
}

/* 字内极小的完整词（装进笔画里，色#0A0A0A，无点缀色） */
.embedded-micro-words {
  position: absolute;
  top: 52%;
  left: 32%;
  transform: translate(-50%, -50%);
  color: #0a0a0a;
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 900;
  letter-spacing: 0.12em;
  background-color: #f4f1ea;
  padding: 1px 4px;
  white-space: nowrap;
  pointer-events: none;
}

.reverse-char-card-meta {
  position: absolute;
  bottom: 12px;
  right: 16px;
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--white-muted);
  letter-spacing: 0.1em;
}

/* ================= 通用 Section 规范 ================= */
.section-block {
  padding: 56px 0;
  border-bottom: 1px solid var(--border-dark);
}

.section-head {
  margin-bottom: 30px;
}

.section-head h2 {
  font-size: 25px;
  font-weight: 800;
  color: var(--white-main);
  display: flex;
  align-items: center;
  gap: 10px;
}

.section-head h2::before {
  content: "";
  display: inline-block;
  width: 6px;
  height: 18px;
  background-color: var(--white-main);
  flex-shrink: 0;
}

.section-sub {
  font-size: 14px;
  color: var(--white-muted);
  margin-top: 6px;
}

/* ================= 3. 特色 Features ================= */
.feature-bars {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 24px;
}

.feature-bar-item {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 24px;
  align-items: center;
  background-color: var(--night-card);
  border: 1px solid var(--border-dark);
  border-radius: var(--radius-sm);
  padding: 18px 22px;
  transition: border-color 0.2s ease, background-color 0.2s ease;
}

.feature-bar-item:hover {
  border-color: var(--border-focus);
  background-color: var(--night-card-sub);
}

.feature-bar-title {
  font-size: 15px;
  font-weight: 800;
  color: var(--white-main);
}

.feature-bar-desc {
  font-size: 14px;
  color: #c4c0b6;
}

.feature-extra-cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

.extra-card {
  background-color: var(--night-card);
  border: 1px solid var(--border-dark);
  border-radius: var(--radius-sm);
  padding: 22px;
}

.extra-card h3 {
  font-size: 16px;
  font-weight: 800;
  color: var(--white-main);
  margin-bottom: 10px;
}

.extra-card p {
  font-size: 14px;
  color: #a8a49c;
  margin-bottom: 14px;
}

.night-box-mono {
  background-color: #050505;
  color: var(--white-main);
  border: 1px solid var(--border-dark);
  border-radius: var(--radius-sm);
  padding: 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.6;
}

.night-box-mono .comment { color: var(--white-muted); }
.night-box-mono .keyword { color: #ffffff; font-weight: bold; }

/* ================= 4. 步骤 Steps ================= */
.steps-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 18px;
}

.step-card {
  background-color: var(--night-card);
  border: 1px solid var(--border-dark);
  border-radius: var(--radius-sm);
  padding: 22px 18px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.step-card:hover {
  border-color: var(--border-focus);
}

.step-num {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--white-main);
  font-weight: 800;
  margin-bottom: 10px;
}

.step-card h3 {
  font-size: 16px;
  font-weight: 800;
  color: var(--white-main);
  margin-bottom: 8px;
}

.step-card p {
  font-size: 13px;
  color: #c4c0b6;
  line-height: 1.6;
}

.step-foot {
  margin-top: 14px;
  padding-top: 10px;
  border-top: 1px dashed var(--border-dark);
  font-size: 11px;
  font-family: var(--font-mono);
  color: var(--white-muted);
}

/* ================= 5. 对照清单 Checklist ================= */
.checklist-card {
  background-color: #070707;
  color: var(--white-main);
  border: 1px solid var(--border-dark);
  border-radius: var(--radius-md);
  padding: 30px;
}

.checklist-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
}

.check-column h3 {
  font-size: 16px;
  font-weight: 800;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-dark);
}

.check-column.required h3 { color: var(--white-main); }
.check-column.avoid h3 { color: var(--white-muted); }

.check-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.check-list li {
  font-size: 14px;
  color: #c4c0b6;
  display: flex;
  gap: 10px;
  align-items: flex-start;
  line-height: 1.6;
}

.check-dot {
  width: 6px;
  height: 6px;
  background-color: var(--white-main);
  margin-top: 8px;
  flex-shrink: 0;
}

.check-dot.muted { background-color: var(--white-muted); }

/* ================= 6. 场景 Scenes ================= */
.scenes-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 18px;
}

.scene-bubble-card {
  background-color: var(--night-card);
  border: 1px solid var(--border-dark);
  border-radius: var(--radius-sm);
  padding: 20px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.scene-role {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
}

.role-badge {
  font-size: 11px;
  font-family: var(--font-mono);
  background-color: var(--night-card-sub);
  color: var(--white-main);
  padding: 2px 8px;
  border-radius: 2px;
  border: 1px solid var(--border-dark);
  font-weight: 700;
}

.scene-bubble-card h3 {
  font-size: 15px;
  font-weight: 800;
  color: var(--white-main);
  margin-bottom: 8px;
}

.scene-quote {
  font-size: 13px;
  color: #c4c0b6;
  line-height: 1.6;
  margin-bottom: 14px;
}

.scene-action-tag {
  font-size: 12px;
  font-family: var(--font-mono);
  color: var(--white-main);
  padding-top: 10px;
  border-top: 1px solid var(--border-dark);
  font-weight: 700;
}

/* ================= 7. 小技巧 Tips ================= */
.tips-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.tip-card {
  background-color: var(--night-card);
  border: 1px solid var(--border-dark);
  border-radius: var(--radius-sm);
  padding: 22px;
}

.tip-card h3 {
  font-size: 15px;
  font-weight: 800;
  color: var(--white-main);
  margin-bottom: 8px;
}

.tip-card p {
  font-size: 13px;
  color: #c4c0b6;
  line-height: 1.6;
}

/* ================= 8. 卡点笔记 Notes ================= */
.notes-container {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.note-item-card {
  background-color: var(--night-card);
  border: 1px solid var(--border-dark);
  border-radius: var(--radius-sm);
  padding: 20px 24px;
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 24px;
  align-items: start;
}

.failure-phenomenon {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.failure-code {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--night-base);
  font-weight: 800;
  background-color: var(--white-main);
  display: inline-block;
  padding: 2px 6px;
  width: fit-content;
}

.failure-phenomenon h3 {
  font-size: 15px;
  font-weight: 800;
  color: var(--white-main);
}

.solution-steps {
  font-size: 13px;
  color: #c4c0b6;
  line-height: 1.7;
}

.solution-steps ol {
  padding-left: 18px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

/* ================= 9. FAQ 手风琴 ================= */
.faq-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

details.faq-item {
  background-color: var(--night-card);
  border: 1px solid var(--border-dark);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

details.faq-item[open] {
  border-color: var(--border-focus);
}

summary.faq-question {
  padding: 16px 20px;
  font-size: 15px;
  font-weight: 800;
  color: var(--white-main);
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
}

summary.faq-question::-webkit-details-marker {
  display: none;
}

summary.faq-question::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 16px;
  color: var(--white-muted);
  font-weight: 700;
}

details[open] summary.faq-question::after {
  content: "—";
}

.faq-answer {
  padding: 0 20px 18px;
  font-size: 14px;
  color: #c4c0b6;
  line-height: 1.7;
  border-top: 1px solid var(--border-dark);
  padding-top: 12px;
}

/* ================= 10. 资讯 News ================= */
.news-list {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin-bottom: 16px;
}

.news-item-link {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 12px;
  background-color: var(--night-card);
  border: 1px solid var(--border-dark);
  border-radius: var(--radius-sm);
  padding: 14px 18px;
  font-size: 14px;
  color: var(--white-main);
}

.news-item-link:hover {
  border-color: var(--white-main);
  background-color: var(--night-card-sub);
}

.news-item-link time {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--white-muted);
  flex-shrink: 0;
}

.news-foot-meta {
  font-size: 12px;
  font-family: var(--font-mono);
  color: var(--white-muted);
  text-align: right;
}

/* ================= 11. 收尾 CTA ================= */
.cta-box {
  background-color: var(--night-card);
  border: 1px solid var(--border-dark);
  border-radius: var(--radius-md);
  padding: 40px 30px;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 18px;
}

.cta-box p {
  font-size: 18px;
  color: var(--white-main);
  max-width: 600px;
}

/* ================= 12. 页脚 Footer ================= */
.site-footer {
  padding: 50px 0 36px;
  background-color: #050505;
  border-top: 1px solid var(--border-dark);
}

.footer-top {
  display: grid;
  grid-template-columns: 1.2fr 1fr 1fr 1fr;
  gap: 30px;
  margin-bottom: 36px;
}

.footer-brand h4 {
  font-size: 15px;
  font-weight: 800;
  color: var(--white-main);
  margin-bottom: 10px;
}

.footer-brand p {
  font-size: 13px;
  color: var(--white-muted);
  line-height: 1.6;
}

.footer-col h5 {
  font-size: 14px;
  font-weight: 800;
  color: var(--white-main);
  margin-bottom: 14px;
}

.footer-col ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.footer-col ul a {
  font-size: 13px;
  color: var(--white-muted);
}

.footer-col ul a:hover {
  color: var(--white-main);
}

.footer-bottom {
  padding-top: 24px;
  border-top: 1px solid var(--border-dark);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 12px;
  color: var(--white-muted);
  font-family: var(--font-mono);
}

/* ================= 响应式适配 Responsive ================= */
@media (max-width: 900px) {
  .hero-grid {
    grid-template-columns: 1fr;
  }
  
  .feature-bar-item {
    grid-template-columns: 1fr;
    gap: 8px;
  }
  
  .feature-extra-cards,
  .checklist-grid,
  .notes-container .note-item-card,
  .news-list {
    grid-template-columns: 1fr;
  }

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

  .tips-grid {
    grid-template-columns: 1fr;
  }

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

@media (max-width: 640px) {
  .hero-content h1 {
    font-size: 28px;
  }

  .hero-content h1 .sub-heading {
    font-size: 16px;
  }

  .section-head h2 {
    font-size: 22px;
  }

  .steps-grid,
  .scenes-grid,
  .footer-top {
    grid-template-columns: 1fr;
  }

  .header-inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}
/* online-perf: skip offscreen sections, keep images inside the column */
section {
  content-visibility: auto;
  contain-intrinsic-size: auto 640px;
}
img {
  max-width: 100%;
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    scroll-behavior: auto !important;
  }
}