/* 智跑科技 — 浅色编辑风 · 独立视觉 */

:root {
  --paper: #faf8f5;
  --paper-dark: #f0ebe3;
  --ink: #1a1a2e;
  --ink-soft: #4a4a5c;
  --accent: #c2410c;
  --accent-hover: #9a3412;
  --line: #d6d0c8;
  --band-dark: #1a1a2e;
  --band-contact: #c2410c;
  --wrap: min(100% - 2rem, 1120px);
  --serif: "Songti SC", "Noto Serif SC", Georgia, "Times New Roman", serif;
  --sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

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

html { scroll-behavior: smooth; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation: none !important;
    transition-duration: 0.01ms !important;
  }
}

body {
  margin: 0;
  font-family: var(--sans);
  font-size: 1rem;
  line-height: 1.7;
  color: var(--ink);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
}

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

a { color: inherit; }

.wrap {
  width: var(--wrap);
  margin-inline: auto;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  padding: 0.5rem 1rem;
  background: var(--ink);
  color: var(--paper);
  z-index: 999;
}

.skip-link:focus {
  left: 1rem;
  top: 1rem;
}

/* —— 顶栏 —— */
.topbar {
  position: fixed;
  inset: 0 0 auto;
  z-index: 50;
  border-bottom: 1px solid transparent;
  transition: background 0.25s, border-color 0.25s, box-shadow 0.25s;
}

.topbar.is-solid {
  background: rgba(250, 248, 245, 0.96);
  border-bottom-color: var(--line);
  box-shadow: 0 1px 0 rgba(26, 26, 46, 0.04);
}

.topbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  min-height: 4rem;
}

.logo {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  font-weight: 700;
  font-size: 0.95rem;
  letter-spacing: 0.06em;
  color: var(--ink);
}

.menu-btn {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.45rem 0.65rem;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: var(--paper);
  color: var(--ink);
  font: inherit;
  font-size: 0.8125rem;
  cursor: pointer;
}

.menu-btn span:first-child,
.menu-btn span:nth-child(2) {
  display: block;
  width: 18px;
  height: 2px;
  background: var(--ink);
  transition: transform 0.2s;
}

.menu-btn span:first-child { margin-bottom: 4px; }

.menu-btn[aria-expanded="true"] span:first-child {
  transform: translateY(3px) rotate(45deg);
  margin-bottom: 0;
}

.menu-btn[aria-expanded="true"] span:nth-child(2) {
  transform: translateY(-3px) rotate(-45deg);
}

.menu {
  display: none;
  position: fixed;
  inset: 4rem 0 0;
  flex-direction: column;
  padding: 2rem 1.5rem;
  background: var(--paper);
  border-top: 1px solid var(--line);
}

.menu.is-open { display: flex; }

.menu a {
  padding: 0.85rem 0;
  font-size: 1.125rem;
  text-decoration: none;
  border-bottom: 1px solid var(--line);
  color: var(--ink-soft);
}

.menu a.is-active { color: var(--accent); font-weight: 600; }

.menu-cta {
  margin-top: 1rem;
  padding: 0.85rem 1.25rem !important;
  background: var(--ink) !important;
  color: var(--paper) !important;
  border: none !important;
  text-align: center;
  border-radius: 2px;
}

@media (min-width: 768px) {
  .menu-btn { display: none; }

  .menu {
    display: flex;
    position: static;
    flex-direction: row;
    align-items: center;
    gap: 0.25rem;
    padding: 0;
    background: transparent;
    border: 0;
  }

  .menu a {
    padding: 0.35rem 0.85rem;
    font-size: 0.875rem;
    border: 0;
    position: relative;
  }

  .menu a:not(.menu-cta)::after {
    content: "";
    position: absolute;
    left: 0.85rem;
    right: 0.85rem;
    bottom: 0;
    height: 2px;
    background: var(--accent);
    transform: scaleX(0);
    transition: transform 0.2s;
  }

  .menu a:not(.menu-cta):hover::after,
  .menu a:not(.menu-cta).is-active::after {
    transform: scaleX(1);
  }

  .menu-cta {
    margin-top: 0;
    margin-left: 0.5rem;
    padding: 0.45rem 1rem !important;
    font-size: 0.8125rem !important;
    background: var(--accent) !important;
    border-radius: 2px;
    transition: background 0.2s;
  }

  .menu-cta:hover { background: var(--accent-hover) !important; }
}

/* —— 首屏 —— */
.intro {
  padding: 6.5rem 0 4rem;
  border-bottom: 1px solid var(--line);
}

.intro-layout {
  display: grid;
  gap: 3rem;
  align-items: center;
}

@media (min-width: 900px) {
  .intro-layout {
    grid-template-columns: 1fr 0.85fr;
    gap: 4rem;
  }
}

.intro-label {
  margin: 0 0 1rem;
  font-size: 0.75rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 600;
}

.intro h1 {
  margin: 0 0 1.25rem;
  font-family: var(--serif);
  font-size: clamp(2.4rem, 6vw, 3.75rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.02em;
}

.intro-lead {
  margin: 0 0 2rem;
  max-width: 32em;
  color: var(--ink-soft);
  font-size: 1.05rem;
}

.intro-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.action {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  font-size: 0.875rem;
  font-weight: 600;
  text-decoration: none;
  border-radius: 2px;
  transition: background 0.2s, color 0.2s, border-color 0.2s;
}

.action-solid {
  background: var(--ink);
  color: var(--paper);
}

.action-solid:hover { background: var(--accent); }

.action-line {
  border: 1px solid var(--ink);
  color: var(--ink);
}

.action-line:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.action-light {
  background: var(--paper);
  color: var(--accent);
  font-size: 1rem;
  padding: 0.85rem 1.75rem;
}

.action-light:hover { background: #fff; }

/* 首屏纯 CSS 视觉 */
.intro-visual {
  position: relative;
  min-height: 280px;
  padding: 2rem;
  background: var(--paper-dark);
  border: 1px solid var(--line);
  overflow: hidden;
}

.track {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 1.25rem;
  padding: 2rem;
}

.lane {
  display: block;
  height: 3px;
  border-radius: 2px;
  background: var(--line);
  transform-origin: left;
  animation: stretch 2.4s ease-in-out infinite;
}

.lane-1 { width: 92%; animation-delay: 0s; background: var(--ink); }
.lane-2 { width: 78%; animation-delay: 0.15s; }
.lane-3 { width: 65%; animation-delay: 0.3s; background: var(--accent); opacity: 0.7; }
.lane-4 { width: 50%; animation-delay: 0.45s; }
.lane-5 { width: 38%; animation-delay: 0.6s; }

@keyframes stretch {
  0%, 100% { transform: scaleX(0.85); opacity: 0.6; }
  50% { transform: scaleX(1); opacity: 1; }
}

.visual-caption {
  position: absolute;
  right: 1.5rem;
  bottom: 1.25rem;
  margin: 0;
  font-size: 0.625rem;
  letter-spacing: 0.18em;
  color: var(--ink-soft);
  writing-mode: vertical-rl;
}

/* —— 通用区块 —— */
.band {
  padding: clamp(3rem, 8vw, 5.5rem) 0;
}

.band + .band { border-top: 1px solid var(--line); }

.band-head {
  display: flex;
  gap: 1.25rem;
  align-items: flex-start;
  margin-bottom: 2.5rem;
}

.band-index {
  flex-shrink: 0;
  font-family: var(--serif);
  font-size: 2rem;
  line-height: 1;
  color: var(--accent);
  opacity: 0.5;
}

.band-head h2 {
  margin: 0 0 0.35rem;
  font-family: var(--serif);
  font-size: clamp(1.5rem, 3vw, 2rem);
}

.band-head p {
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.9375rem;
}

/* —— 关于 —— */
.pull-quote {
  margin: 0 0 2.5rem;
  padding: 0 0 0 1.25rem;
  border-left: 4px solid var(--accent);
  font-family: var(--serif);
  font-size: clamp(1.15rem, 2.5vw, 1.45rem);
  line-height: 1.55;
  color: var(--ink);
}

.about-columns {
  display: grid;
  gap: 2rem;
}

@media (min-width: 768px) {
  .about-columns { grid-template-columns: 1fr 1.2fr; }
}

.about-col h2 {
  margin: 0 0 0.75rem;
  font-family: var(--serif);
  font-size: 1.25rem;
}

.about-col p {
  margin: 0;
  color: var(--ink-soft);
}

.about-col p + p { margin-top: 1rem; }

.about-note {
  padding-top: 1rem;
  border-top: 1px dashed var(--line);
  font-size: 0.8125rem !important;
  color: var(--ink-soft) !important;
}

/* —— 业务列表 —— */
.service-list {
  list-style: none;
  margin: 0;
  padding: 0;
  counter-reset: svc;
}

.service-item {
  display: grid;
  gap: 1rem;
  padding: 1.75rem 0;
  border-bottom: 1px solid var(--line);
}

.service-item:first-child { padding-top: 0; }

.service-item:last-child { border-bottom: 0; }

@media (min-width: 640px) {
  .service-item {
    grid-template-columns: 5rem 1fr;
    gap: 2rem;
    align-items: start;
  }
}

.service-meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

@media (min-width: 640px) {
  .service-meta {
    flex-direction: column;
    align-items: flex-start;
  }
}

.service-no {
  font-family: var(--serif);
  font-size: 1.75rem;
  color: var(--line);
  line-height: 1;
}

.service-body h3 {
  margin: 0 0 0.25rem;
  font-size: 1.125rem;
}

.service-tag {
  margin: 0 0 0.65rem;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--accent);
}

.service-body p:last-child {
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.9375rem;
}

/* —— 优势 —— */
.band-why { background: var(--paper-dark); }

.reason-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.reason-list li {
  display: grid;
  grid-template-columns: 3rem 1fr;
  gap: 1.25rem;
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--line);
}

.reason-list li:last-child { border-bottom: 0; }

.reason-index {
  font-family: var(--serif);
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--accent);
  line-height: 1;
}

.reason-list h3 {
  margin: 0 0 0.4rem;
  font-size: 1.05rem;
}

.reason-list p {
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.9375rem;
}

/* —— 联系 —— */
.band-contact {
  background: var(--band-contact);
  color: var(--paper);
  border-top: 0;
}

.contact-inner {
  display: grid;
  gap: 2rem;
  align-items: end;
}

@media (min-width: 768px) {
  .contact-inner {
    grid-template-columns: 1fr auto;
    gap: 3rem;
  }
}

.band-contact h2 {
  margin: 0 0 0.75rem;
  font-family: var(--serif);
  font-size: clamp(1.5rem, 3vw, 2.25rem);
  line-height: 1.25;
}

.band-contact p {
  margin: 0;
  max-width: 28em;
  opacity: 0.9;
  font-size: 0.9375rem;
}

/* —— 页脚 —— */
.foot {
  background: var(--band-dark);
  color: rgba(250, 248, 245, 0.75);
  padding: 2.5rem 0 0;
  font-size: 0.875rem;
}

.foot-grid {
  display: grid;
  gap: 1.5rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

@media (min-width: 640px) {
  .foot-grid { grid-template-columns: 1.2fr 1fr 1fr; }
}

.foot-name {
  margin: 0 0 0.25rem;
  font-weight: 700;
  color: var(--paper);
  letter-spacing: 0.06em;
}

.foot-desc { margin: 0; font-size: 0.8125rem; }

.foot-label {
  margin: 0 0 0.35rem;
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: rgba(250, 248, 245, 0.45);
}

.foot-col a {
  color: var(--paper);
  text-decoration: none;
}

.foot-col a:hover { text-decoration: underline; }

.foot-copy { margin: 0; }

.foot-icp-row {
  padding: 1.25rem 0 1.5rem;
  text-align: center;
}

.foot-icp-row a {
  color: rgba(250, 248, 245, 0.55);
  font-size: 0.8125rem;
  text-decoration: none;
}

.foot-icp-row a:hover {
  color: var(--paper);
  text-decoration: underline;
}

@media (max-width: 479px) {
  .intro { padding-top: 5.5rem; }

  .intro-visual { min-height: 220px; }

  .visual-caption { writing-mode: horizontal-tb; right: auto; left: 1.25rem; }
}