/* TaskLink 网站基础视觉系统：品牌变量、排版、导航、按钮、页脚、主题与通用响应式规则。 */
:root {
  color-scheme: light;
  --page: #f2f2f7;
  --page-deep: #e9f2fb;
  --card: #ffffff;
  --card-elevated: rgba(255, 255, 255, 0.88);
  --surface: #f7f8fa;
  --surface-blue: #e8f2ff;
  --line: #dadae0;
  --line-soft: rgba(17, 17, 17, 0.08);
  --text: #111111;
  --text-soft: #3a3a3c;
  --muted: #73737a;
  --faint: #a1a1aa;
  --blue: #1e88e5;
  --blue-deep: #0876d1;
  --cyan: #44d2df;
  --green: #34c759;
  --lime: #9dea5b;
  --orange: #ff9500;
  --red: #ff3b30;
  --violet: #5e5ce6;
  --shadow-sm: 0 10px 32px rgba(31, 54, 83, 0.08);
  --shadow-lg: 0 34px 90px rgba(30, 68, 112, 0.17);
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", sans-serif;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --page: #090b0e;
  --page-deep: #0c1822;
  --card: #1a1e24;
  --card-elevated: rgba(26, 30, 36, 0.88);
  --surface: #252b33;
  --surface-blue: #14324a;
  --line: #343a43;
  --line-soft: rgba(255, 255, 255, 0.09);
  --text: #f2f4f7;
  --text-soft: #d4d4d8;
  --muted: #a8b0bc;
  --faint: #7e8793;
  --blue: #4ea3f1;
  --blue-deep: #78b9f3;
  --cyan: #5ed7e1;
  --green: #4ade80;
  --lime: #a7ed70;
  --orange: #ffb454;
  --red: #ff6961;
  --shadow-sm: 0 12px 36px rgba(0, 0, 0, 0.22);
  --shadow-lg: 0 36px 90px rgba(0, 0, 0, 0.42);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 96px;
}

body {
  margin: 0;
  min-width: 320px;
  min-height: 100vh;
  overflow-x: hidden;
  color: var(--text);
  background: var(--page);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

a {
  color: inherit;
  text-decoration: none;
}

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

button {
  font: inherit;
}

::selection {
  color: #fff;
  background: var(--blue);
}

.shell {
  width: min(1180px, calc(100% - 48px));
  margin-inline: auto;
}

.skip-link {
  position: fixed;
  top: 12px;
  left: 12px;
  z-index: 1000;
  padding: 10px 14px;
  border-radius: 12px;
  color: #fff;
  background: var(--blue);
  transform: translateY(-160%);
  transition: transform 180ms ease;
}

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

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 1px solid transparent;
  background: color-mix(in srgb, var(--page) 78%, transparent);
  backdrop-filter: blur(20px) saturate(1.4);
  -webkit-backdrop-filter: blur(20px) saturate(1.4);
  transition: border-color 180ms ease, box-shadow 180ms ease;
}

.site-header.is-scrolled {
  border-color: var(--line-soft);
  box-shadow: 0 8px 30px rgba(28, 45, 67, 0.06);
}

.header-inner {
  display: flex;
  min-height: 72px;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
}

.brand {
  display: inline-flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 11px;
}

.brand img {
  border: 1px solid var(--line-soft);
  border-radius: 11px;
  box-shadow: 0 6px 15px rgba(25, 91, 150, 0.16);
}

.brand-name {
  font-size: 18px;
  font-weight: 760;
  letter-spacing: -0.02em;
}

.brand-badge {
  padding: 3px 8px;
  border: 1px solid color-mix(in srgb, var(--blue) 26%, transparent);
  border-radius: 999px;
  color: var(--blue-deep);
  background: var(--surface-blue);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.main-nav {
  display: flex;
  align-items: center;
  gap: 30px;
  color: var(--muted);
  font-size: 14px;
  font-weight: 580;
}

.main-nav a,
.footer-links a {
  transition: color 160ms ease;
}

.main-nav a:hover,
.main-nav a:focus-visible,
.footer-links a:hover,
.footer-links a:focus-visible {
  color: var(--blue);
}

.header-actions {
  display: flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 10px;
}

.theme-toggle {
  position: relative;
  display: grid;
  width: 38px;
  height: 38px;
  padding: 0;
  overflow: hidden;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 13px;
  color: var(--text-soft);
  background: var(--card-elevated);
  cursor: pointer;
  transition: transform 160ms ease, border-color 160ms ease, background 160ms ease;
}

.theme-toggle:hover {
  border-color: color-mix(in srgb, var(--blue) 42%, var(--line));
  transform: translateY(-1px);
}

.theme-icon {
  position: absolute;
  font-size: 17px;
  line-height: 1;
  transition: opacity 160ms ease, transform 220ms ease;
}

.theme-icon-moon {
  opacity: 0;
  transform: translateY(18px) rotate(35deg);
}

:root[data-theme="dark"] .theme-icon-sun {
  opacity: 0;
  transform: translateY(-18px) rotate(-35deg);
}

:root[data-theme="dark"] .theme-icon-moon {
  opacity: 1;
  transform: translateY(0) rotate(0);
}

.header-contact {
  display: inline-flex;
  min-height: 38px;
  padding: 0 15px;
  align-items: center;
  justify-content: center;
  border-radius: 13px;
  color: #fff;
  background: var(--blue);
  font-size: 13px;
  font-weight: 650;
  box-shadow: 0 8px 18px color-mix(in srgb, var(--blue) 24%, transparent);
  transition: transform 160ms ease, background 160ms ease;
}

.header-contact:hover,
.header-contact:focus-visible {
  background: var(--blue-deep);
  transform: translateY(-1px);
}

.button {
  display: inline-flex;
  min-height: 50px;
  padding: 0 20px;
  align-items: center;
  justify-content: center;
  gap: 10px;
  border: 1px solid transparent;
  border-radius: 16px;
  font-size: 15px;
  font-weight: 680;
  line-height: 1;
  transition: transform 180ms ease, box-shadow 180ms ease, background 180ms ease, border-color 180ms ease;
}

.button:hover,
.button:focus-visible {
  transform: translateY(-2px);
}

.button-primary {
  color: #fff;
  background: var(--blue);
  box-shadow: 0 14px 28px color-mix(in srgb, var(--blue) 26%, transparent);
}

.button-primary:hover,
.button-primary:focus-visible {
  background: var(--blue-deep);
  box-shadow: 0 18px 34px color-mix(in srgb, var(--blue) 32%, transparent);
}

.button-secondary {
  border-color: var(--line);
  color: var(--text-soft);
  background: var(--card-elevated);
  box-shadow: var(--shadow-sm);
}

.button-secondary:hover,
.button-secondary:focus-visible {
  border-color: color-mix(in srgb, var(--blue) 36%, var(--line));
  color: var(--blue-deep);
}

.section-heading {
  max-width: 680px;
}

.section-heading h2,
.privacy-copy h2,
.reliability-copy h2 {
  margin: 0;
  font-size: clamp(34px, 5vw, 54px);
  font-weight: 780;
  letter-spacing: -0.045em;
  line-height: 1.12;
}

.section-heading > p:last-child {
  margin: 18px 0 0;
  color: var(--muted);
  font-size: 18px;
  line-height: 1.75;
}

.section-kicker {
  margin: 0 0 12px;
  color: var(--blue);
  font-size: 13px;
  font-weight: 760;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.light-kicker {
  color: #81c2ff;
}

.centered-heading {
  margin-inline: auto;
  text-align: center;
}

.text-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--blue);
  font-weight: 680;
}

.text-link span {
  transition: transform 160ms ease;
}

.text-link:hover span {
  transform: translateX(4px);
}

.site-footer {
  margin-top: 110px;
  padding: 54px 0 30px;
  border-top: 1px solid var(--line-soft);
  background: color-mix(in srgb, var(--card) 38%, var(--page));
}

.footer-main {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(320px, 0.8fr);
  gap: 80px;
  padding-bottom: 40px;
}

.footer-brand p {
  max-width: 430px;
  margin: 18px 0 0;
  color: var(--muted);
}

.footer-links {
  display: grid;
  grid-template-columns: repeat(2, minmax(120px, 1fr));
  gap: 36px;
}

.footer-links div {
  display: flex;
  flex-direction: column;
  gap: 9px;
  color: var(--muted);
  font-size: 14px;
}

.footer-links strong {
  margin-bottom: 5px;
  color: var(--text);
}

.footer-bottom {
  display: flex;
  padding-top: 22px;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  border-top: 1px solid var(--line-soft);
  color: var(--muted);
  font-size: 13px;
}

.footer-bottom p {
  margin: 0;
}

.footer-bottom a:hover {
  color: var(--blue);
}

.trademark-note {
  margin-top: 14px;
  color: var(--faint);
  font-size: 11px;
}

.js .reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 700ms cubic-bezier(0.22, 1, 0.36, 1), transform 700ms cubic-bezier(0.22, 1, 0.36, 1);
}

.js .reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

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

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

  .js .reveal {
    opacity: 1;
    transform: none;
  }
}

@media (max-width: 900px) {
  .main-nav {
    display: none;
  }

  .footer-main {
    grid-template-columns: 1fr;
    gap: 42px;
  }

  .footer-links {
    max-width: 420px;
  }
}

@media (max-width: 640px) {
  .shell {
    width: min(100% - 28px, 1180px);
  }

  .header-inner {
    min-height: 64px;
    gap: 12px;
  }

  .brand-badge,
  .header-contact {
    display: none;
  }

  .brand img {
    width: 36px;
    height: 36px;
  }

  .site-footer {
    margin-top: 76px;
    padding-top: 42px;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}