/* ==========================================================================
   忒嗨 TEHI — 官网样式（高级灰 · 科技感）
   设计变量集中在 :root，改配色只需改这里
   ========================================================================== */

:root {
  --color-ink: #14161A;
  --color-ink-deep: #0A0B0D;
  --color-slate: #3A3D44;
  --color-accent: #5B6472;
  --color-accent-light: #A6ACB6;
  --color-accent-cta: #4A5568;
  --color-white: #FFFFFF;
  --color-bg: #F3F4F6;
  --color-bg-alt: #E8E9EC;
  --color-surface: #FFFFFF;
  --color-text-muted: #6B7078;
  --color-border: #DFE1E5;

  --font-sans: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;

  --max-width: 1200px;
  --pad-mobile: 24px;
  --pad-desktop: 48px;

  --radius: 16px;
  --radius-sm: 10px;
  --shadow-card: 0 4px 20px rgba(20, 22, 26, 0.06);
  --shadow-card-hover: 0 12px 32px rgba(20, 22, 26, 0.1);
  --shadow-header: 0 2px 16px rgba(20, 22, 26, 0.08);
}

/* ---- Reset & base ---- */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  color: var(--color-ink);
  background: var(--color-white);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

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

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

ul {
  list-style: none;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--pad-mobile);
}

@media (min-width: 1024px) {
  .container {
    padding: 0 var(--pad-desktop);
  }
}

section {
  padding: 88px 0;
  position: relative;
}

.section-alt {
  background: var(--color-bg);
}

.section-heading {
  text-align: center;
  margin-bottom: 52px;
}

.section-heading .tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--color-accent);
  font-weight: 700;
  font-size: 13px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 16px;
}

.section-heading .tag::before {
  content: "";
  width: 24px;
  height: 1px;
  background: var(--color-accent);
}

.section-heading h2 {
  font-size: 30px;
  font-weight: 800;
  color: var(--color-ink);
  letter-spacing: -0.01em;
}

.section-heading p {
  margin-top: 14px;
  color: var(--color-text-muted);
  max-width: 640px;
  margin-left: auto;
  margin-right: auto;
  font-size: 15px;
}

/* ---- Header / Nav ---- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-border);
  transition: box-shadow 0.2s ease;
}

.site-header.is-scrolled {
  box-shadow: var(--shadow-header);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
}

.brand img {
  max-height: 26px;
  width: auto;
  object-fit: contain;
}

.brand span {
  font-weight: 800;
  font-size: 11.5px;
  color: var(--color-ink);
  letter-spacing: 0;
  line-height: 1.3;
  white-space: nowrap;
}

@media (min-width: 768px) {
  .brand img {
    max-height: 36px;
  }
  .brand span {
    font-size: 18px;
    letter-spacing: 0.01em;
  }
}

.nav-links {
  display: none;
  align-items: center;
  gap: 4px;
}

.nav-links a {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-slate);
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  transition: background 0.2s ease, color 0.2s ease;
}

.nav-links a:hover {
  background: var(--color-bg);
  color: var(--color-ink);
}

.nav-links a.active {
  background: var(--color-ink);
  color: var(--color-white);
}

.nav-toggle {
  display: flex;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

.nav-toggle span {
  width: 22px;
  height: 2px;
  background: var(--color-ink);
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.nav-toggle.is-open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle.is-open span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.is-open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.nav-links-mobile {
  display: none;
  flex-direction: column;
  padding: 8px var(--pad-mobile) 20px;
  border-top: 1px solid var(--color-border);
}

.nav-links-mobile.is-open {
  display: flex;
}

.nav-links-mobile a {
  padding: 12px 16px;
  font-size: 15px;
  font-weight: 600;
  border-radius: var(--radius-sm);
}

.nav-links-mobile a.active {
  background: var(--color-ink);
  color: var(--color-white);
}

@media (min-width: 768px) {
  .nav-links {
    display: flex;
  }
  .nav-toggle {
    display: none;
  }
  .nav-links-mobile {
    display: none !important;
  }
}

/* ---- Hero ---- */
.hero {
  background:
    radial-gradient(ellipse at 20% -10%, rgba(120, 128, 145, 0.28), transparent 55%),
    radial-gradient(ellipse at 90% 10%, rgba(166, 172, 182, 0.14), transparent 50%),
    linear-gradient(180deg, var(--color-ink) 0%, var(--color-ink-deep) 100%);
  color: var(--color-white);
  padding: 120px 0 104px;
  text-align: center;
  overflow: hidden;
}

.hero-blob {
  display: none;
}

.hero .container {
  position: relative;
  z-index: 1;
}

.hero-brand {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  margin: 0 auto 28px;
  max-width: 280px;
}

.hero-brand img {
  height: 40px;
  width: auto;
  object-fit: contain;
}

.hero-brand span {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: rgba(255, 255, 255, 0.6);
  text-align: center;
  line-height: 1.4;
}

@media (min-width: 768px) {
  .hero-brand img {
    height: 52px;
  }
  .hero-brand span {
    font-size: 13px;
  }
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-accent-light);
  margin-bottom: 24px;
}

.hero-eyebrow::before,
.hero-eyebrow::after {
  content: "";
  width: 20px;
  height: 1px;
  background: var(--color-accent-light);
  opacity: 0.6;
}

.hero h1 {
  font-size: 36px;
  font-weight: 800;
  letter-spacing: -0.01em;
  max-width: 780px;
  margin: 0 auto 22px;
  line-height: 1.35;
}

.hero p {
  font-size: 16px;
  color: rgba(255, 255, 255, 0.65);
  max-width: 620px;
  margin: 0 auto 40px;
  line-height: 1.8;
}

.btn {
  display: inline-block;
  padding: 14px 32px;
  border-radius: var(--radius-sm);
  font-weight: 700;
  font-size: 15px;
  cursor: pointer;
  border: none;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.2s ease;
}

.btn-accent {
  background: var(--color-accent-cta);
  color: var(--color-white);
  box-shadow: 0 8px 24px rgba(74, 85, 104, 0.35);
}

.btn-accent:hover {
  background: #3B4456;
  transform: translateY(-2px);
  box-shadow: 0 12px 28px rgba(74, 85, 104, 0.45);
}

.btn-outline {
  background: transparent;
  color: var(--color-white);
  border: 1px solid rgba(255, 255, 255, 0.3);
}

.btn-outline:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.5);
}

@media (min-width: 768px) {
  .hero h1 {
    font-size: 46px;
  }
}

/* ---- Pillar grid / cards ---- */
.pillar-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 20px;
}

.pillar-grid .card {
  flex: 1 1 230px;
  max-width: 280px;
}

/* 固定4卡片板块：始终整齐排列，不出现"3+1"散落 */
.pillar-grid--4up {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.pillar-grid--4up .card {
  max-width: none;
}

@media (min-width: 900px) {
  .pillar-grid--4up {
    grid-template-columns: repeat(4, 1fr);
  }
}

.card {
  background: var(--color-surface);
  border-radius: var(--radius);
  padding: 30px 26px;
  box-shadow: var(--shadow-card);
  border: 1px solid var(--color-border);
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-card-hover);
  border-color: var(--color-accent);
}

.card-icon {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  font-weight: 800;
  color: var(--color-slate);
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  margin-bottom: 20px;
  font-variant-numeric: tabular-nums;
}

.card h3 {
  font-size: 16px;
  font-weight: 700;
  color: var(--color-ink);
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.card p {
  font-size: 14px;
  color: var(--color-text-muted);
}

.tag-new {
  display: inline-block;
  background: var(--color-ink);
  color: var(--color-white);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.08em;
  padding: 3px 10px;
  border-radius: 999px;
  margin-left: 8px;
  vertical-align: middle;
}

/* ---- IP section: showcase layout ---- */
.ip-showcase {
  display: flex;
  flex-direction: column;
  gap: 32px;
  margin-bottom: 0;
}

@media (min-width: 900px) {
  .ip-showcase {
    flex-direction: row;
    align-items: flex-start;
    gap: 40px;
  }
}

.ip-feature {
  flex: 0 0 auto;
  text-align: center;
}

.ip-feature img {
  max-width: 100%;
  width: auto;
  max-height: 420px;
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  border: 1px solid var(--color-border);
}

.ip-feature figcaption {
  margin-top: 12px;
  font-size: 13px;
  font-weight: 700;
  color: var(--color-text-muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.ip-showcase .pillar-grid--4up {
  flex: 1;
  grid-template-columns: repeat(2, 1fr);
}

@media (min-width: 900px) {
  .ip-feature {
    max-width: 50%;
  }
  .ip-feature img {
    max-height: 480px;
  }
}

/* ---- Empower strip (SME enablement callout) ---- */
.empower-strip {
  margin-top: 40px;
  padding: 28px 32px;
  background: var(--color-ink);
  border-radius: var(--radius);
  color: var(--color-white);
  display: flex;
  align-items: center;
  gap: 20px;
  flex-wrap: wrap;
}

.empower-strip .empower-icon {
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-accent-light);
  white-space: nowrap;
}

.empower-strip p {
  font-size: 14px;
  color: rgba(255, 255, 255, 0.75);
  flex: 1;
  min-width: 240px;
}

/* ---- About ---- */
.about-content {
  max-width: 760px;
  margin: 0 auto;
  text-align: center;
  color: var(--color-ink);
  font-size: 16px;
  line-height: 1.9;
}

/* ---- Contact ---- */
.contact {
  background:
    radial-gradient(ellipse at 80% 0%, rgba(120, 128, 145, 0.24), transparent 55%),
    linear-gradient(180deg, var(--color-ink) 0%, var(--color-ink-deep) 100%);
  color: var(--color-white);
  text-align: center;
}

.contact .section-heading .tag {
  color: var(--color-accent-light);
}

.contact .section-heading .tag::before {
  background: var(--color-accent-light);
}

.contact .section-heading h2 {
  color: var(--color-white);
}

.contact p {
  color: rgba(255, 255, 255, 0.65);
  max-width: 560px;
  margin: 0 auto 32px;
}

.contact-info {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: 32px;
  font-size: 14px;
  color: rgba(255, 255, 255, 0.6);
}

/* ---- Footer ---- */
.site-footer {
  background: var(--color-ink-deep);
  color: rgba(255, 255, 255, 0.5);
  text-align: center;
  padding: 28px 0;
  font-size: 13px;
}

/* ---- Responsive tweaks ---- */
@media (min-width: 1024px) {
  section {
    padding: 112px 0;
  }
}