/* ============================================================
   「找老同学」官网 极简商务风
   ============================================================ */

/* ---------- CSS 变量 ---------- */
:root {
  --color-primary: #1F3A5F;
  --color-primary-soft: #2D4F7A;
  --color-accent: #07C160;
  --color-accent-soft: #08A14F;
  --color-bg: #FAF6EE;
  --color-bg-alt: #FFFFFF;
  --color-text: #1A1A1A;
  --color-text-soft: #5A5A5A;
  --color-text-mute: #8A8A8A;
  --color-divider: #EAE6DD;
  --color-card-shadow: rgba(31, 58, 95, .08);
  --color-card-shadow-hover: rgba(31, 58, 95, .16);

  --font-cn: 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', 'Noto Sans CJK SC', sans-serif;
  --font-en: 'Inter', 'Helvetica Neue', Arial, sans-serif;
  --font-base: var(--font-en), var(--font-cn);

  --radius-sm: 8px;
  --radius-md: 16px;
  --radius-lg: 24px;

  --shadow-sm: 0 2px 8px var(--color-card-shadow);
  --shadow-md: 0 8px 24px var(--color-card-shadow);
  --shadow-lg: 0 16px 48px var(--color-card-shadow-hover);

  --transition: 280ms cubic-bezier(.2, .7, .2, 1);

  --container-max: 1200px;
  --container-narrow: 880px;
}

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

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: var(--font-base);
  font-size: 16px;
  line-height: 1.7;
  color: var(--color-text);
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img { max-width: 100%; display: block; }
a { color: var(--color-primary); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--color-accent); }
button { font-family: inherit; cursor: pointer; }

/* ---------- 容器 ---------- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 32px;
}
.container--narrow { max-width: var(--container-narrow); }

/* ---------- 顶部导航 ---------- */
.nav {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 100;
  background: rgba(250, 246, 238, .75);
  backdrop-filter: saturate(160%) blur(14px);
  -webkit-backdrop-filter: saturate(160%) blur(14px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition), background var(--transition);
}
.nav.is-scrolled { border-bottom-color: var(--color-divider); }

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

.nav__brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--color-primary);
}
.nav__logo {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  object-fit: cover;
}
.nav__title {
  font-weight: 600;
  font-size: 18px;
  letter-spacing: .5px;
}

.nav__menu {
  display: flex;
  align-items: center;
  gap: 36px;
}
.nav__link {
  color: var(--color-text);
  font-size: 15px;
  font-weight: 500;
  position: relative;
  padding: 4px 0;
}
.nav__link::after {
  content: '';
  position: absolute;
  left: 50%;
  bottom: 0;
  width: 0;
  height: 2px;
  background: var(--color-accent);
  transition: width var(--transition), left var(--transition);
}
.nav__link:hover::after,
.nav__link.is-active::after { width: 100%; left: 0; }
.nav__link--cta {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  background: var(--color-accent);
  color: #fff;
}
.nav__link--cta:hover { background: var(--color-accent-soft); color: #fff; }
.nav__link--cta::after { display: none; }

.nav__toggle {
  display: none;
  background: transparent;
  border: 0;
  font-size: 22px;
  color: var(--color-primary);
  padding: 8px;
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  padding: 160px 0 120px;
  background: linear-gradient(180deg, var(--color-bg) 0%, var(--color-bg) 60%, var(--color-bg-alt) 100%);
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: -200px;
  right: -200px;
  width: 600px;
  height: 600px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(7, 193, 96, .08), transparent 70%);
  pointer-events: none;
}
.hero__inner {
  display: grid;
  grid-template-columns: 1.2fr .8fr;
  gap: 80px;
  align-items: center;
  position: relative;
}

.hero__eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 0 0 24px;
  padding: 6px 14px;
  font-size: 13px;
  font-weight: 600;
  color: var(--color-accent);
  background: rgba(7, 193, 96, .08);
  border-radius: 999px;
  letter-spacing: 1px;
}

.hero__title {
  margin: 0 0 24px;
  font-size: clamp(40px, 5vw, 64px);
  line-height: 1.15;
  font-weight: 700;
  color: var(--color-primary);
  letter-spacing: -.5px;
}

.hero__lede {
  margin: 0 0 32px;
  font-size: 17px;
  line-height: 1.8;
  color: var(--color-text-soft);
  max-width: 540px;
}
.hero__lede strong { color: var(--color-primary); font-weight: 600; }

.hero__bullets {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 18px 28px;
}
.hero__bullets li {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--color-text);
  font-weight: 500;
}
.hero__bullets i { color: var(--color-accent); }

.hero__visual { display: flex; justify-content: center; }
.hero__card {
  background: var(--color-bg-alt);
  border-radius: var(--radius-lg);
  padding: 40px;
  text-align: center;
  box-shadow: var(--shadow-lg);
  max-width: 360px;
  width: 100%;
  position: relative;
}
.hero__card::before {
  content: '';
  position: absolute;
  inset: -1px;
  border-radius: inherit;
  padding: 1px;
  background: linear-gradient(135deg, var(--color-accent), var(--color-primary));
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
          mask-composite: exclude;
  opacity: .35;
  pointer-events: none;
}
.hero__logo {
  width: 72px;
  height: 72px;
  margin: 0 auto 16px;
  border-radius: var(--radius-sm);
}
.hero__product {
  margin: 0 0 24px;
  font-size: 14px;
  color: var(--color-text-mute);
  letter-spacing: .5px;
}
.hero__qr {
  margin: 0 auto 16px;
  width: 220px;
  height: 220px;
  border-radius: var(--radius-md);
  background: var(--color-bg);
  padding: 12px;
  box-shadow: var(--shadow-sm);
  animation: qr-breath 3s ease-in-out infinite;
}
.hero__qr img { width: 100%; height: 100%; border-radius: 8px; }
.hero__hint {
  margin: 0;
  font-size: 14px;
  color: var(--color-primary);
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.hero__hint i { color: var(--color-accent); font-size: 18px; }

@keyframes qr-breath {
  0%, 100% { box-shadow: 0 0 0 0 rgba(7, 193, 96, .35), var(--shadow-sm); }
  50%      { box-shadow: 0 0 0 12px rgba(7, 193, 96, 0),   var(--shadow-sm); }
}

.hero__scroll {
  position: absolute;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%);
  width: 40px;
  height: 40px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: var(--color-bg-alt);
  color: var(--color-primary);
  box-shadow: var(--shadow-sm);
  animation: bounce 2.4s ease-in-out infinite;
}
@keyframes bounce {
  0%, 100% { transform: translate(-50%, 0); }
  50%      { transform: translate(-50%, 8px); }
}

/* ---------- 通用 section ---------- */
.section {
  padding: 120px 0;
  background: var(--color-bg-alt);
}
.section--alt { background: var(--color-bg); }

.section__head {
  text-align: center;
  margin-bottom: 64px;
}
.section__eyebrow {
  margin: 0 0 12px;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 3px;
  color: var(--color-accent);
}
.section__title {
  margin: 0 0 16px;
  font-size: clamp(28px, 3vw, 40px);
  font-weight: 700;
  color: var(--color-primary);
  letter-spacing: -.3px;
}
.section__lede {
  margin: 0;
  font-size: 16px;
  color: var(--color-text-soft);
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

/* ---------- Overview ---------- */
.overview {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: 64px;
  align-items: start;
}
.overview__main p {
  font-size: 17px;
  line-height: 1.9;
  color: var(--color-text-soft);
  margin: 0 0 20px;
}
.overview__main strong { color: var(--color-primary); font-weight: 600; }
.overview__main em { font-style: normal; color: var(--color-accent); font-weight: 600; }

.overview__stats {
  display: flex;
  flex-direction: column;
  gap: 20px;
}
.stat {
  padding: 24px;
  background: var(--color-bg);
  border-radius: var(--radius-md);
  border-left: 4px solid var(--color-accent);
  transition: transform var(--transition), box-shadow var(--transition);
}
.stat:hover { transform: translateX(4px); box-shadow: var(--shadow-md); }
.stat i {
  font-size: 22px;
  color: var(--color-accent);
  margin-bottom: 8px;
}
.stat h3 {
  margin: 0 0 6px;
  font-size: 18px;
  color: var(--color-primary);
}
.stat p {
  margin: 0;
  font-size: 14px;
  color: var(--color-text-soft);
}

/* ---------- Features ---------- */
.features {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}
.card {
  padding: 36px;
  background: var(--color-bg-alt);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-divider);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}
.card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-md);
  border-color: transparent;
}
.card__icon {
  width: 56px;
  height: 56px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  background: rgba(7, 193, 96, .08);
  color: var(--color-accent);
  font-size: 24px;
  margin-bottom: 24px;
}
.card__title {
  margin: 0 0 14px;
  font-size: 20px;
  font-weight: 600;
  color: var(--color-primary);
}
.card__body {
  margin: 0 0 20px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--color-text-soft);
}
.card__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.card__list li {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  color: var(--color-text);
}
.card__list i { color: var(--color-accent); font-size: 13px; }

/* ---------- Steps ---------- */
.steps {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  counter-reset: step;
  position: relative;
}
.steps::before {
  content: '';
  position: absolute;
  top: 36px;
  left: 12%;
  right: 12%;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--color-divider) 8%, var(--color-divider) 92%, transparent);
  z-index: 0;
}
.step {
  text-align: center;
  position: relative;
  z-index: 1;
}
.step__num {
  width: 72px;
  height: 72px;
  margin: 0 auto 20px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: var(--color-bg-alt);
  border: 2px solid var(--color-primary);
  color: var(--color-primary);
  font-size: 32px;
  font-weight: 700;
  font-family: var(--font-en);
  transition: all var(--transition);
}
.step:hover .step__num {
  background: var(--color-primary);
  color: #fff;
  transform: scale(1.06);
}
.step__title {
  margin: 0 0 10px;
  font-size: 17px;
  font-weight: 600;
  color: var(--color-primary);
}
.step__body {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-text-soft);
  padding: 0 8px;
}

/* ---------- Rules ---------- */
.rules {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.rule {
  padding: 32px;
  background: var(--color-bg-alt);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-divider);
  transition: transform var(--transition), box-shadow var(--transition);
}
.rule:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); }
.rule__index {
  display: inline-block;
  font-family: var(--font-en);
  font-size: 36px;
  font-weight: 700;
  color: var(--color-accent);
  margin-bottom: 16px;
  letter-spacing: -1px;
}
.rule h3 {
  margin: 0 0 10px;
  font-size: 18px;
  color: var(--color-primary);
}
.rule p {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--color-text-soft);
}

/* ---------- Privacy ---------- */
.privacy {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.privacy__item {
  padding: 36px;
  background: var(--color-bg);
  border-radius: var(--radius-md);
  text-align: center;
  transition: transform var(--transition);
}
.privacy__item:hover { transform: translateY(-4px); }
.privacy__item i {
  font-size: 32px;
  color: var(--color-accent);
  margin-bottom: 16px;
}
.privacy__item h3 {
  margin: 0 0 10px;
  font-size: 18px;
  color: var(--color-primary);
}
.privacy__item p {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--color-text-soft);
}

/* ---------- FAQ ---------- */
.faq {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.faq__item {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-divider);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color var(--transition), box-shadow var(--transition);
}
.faq__item.is-open {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-md);
}
.faq__q {
  width: 100%;
  background: transparent;
  border: 0;
  padding: 22px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  text-align: left;
  font-size: 16px;
  font-weight: 600;
  color: var(--color-primary);
  transition: color var(--transition);
}
.faq__q:hover { color: var(--color-accent); }
.faq__chevron {
  font-size: 14px;
  transition: transform var(--transition);
  flex-shrink: 0;
  color: var(--color-text-mute);
}
.faq__item.is-open .faq__chevron {
  transform: rotate(180deg);
  color: var(--color-accent);
}
.faq__a {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition);
}
.faq__a p {
  margin: 0;
  padding: 0 24px 24px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--color-text-soft);
}

/* ---------- CTA ---------- */
.cta {
  background: linear-gradient(135deg, var(--color-primary) 0%, #2C4F7A 100%);
  color: #fff;
}
.cta__inner {
  display: grid;
  grid-template-columns: 1.4fr .6fr;
  gap: 64px;
  align-items: center;
}
.cta__title {
  margin: 0 0 20px;
  font-size: clamp(28px, 3.4vw, 42px);
  font-weight: 700;
  line-height: 1.25;
}
.cta__lede {
  margin: 0 0 28px;
  font-size: 16px;
  line-height: 1.8;
  color: rgba(255, 255, 255, .85);
  max-width: 520px;
}
.cta__points {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 18px 28px;
}
.cta__points li {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: rgba(255, 255, 255, .92);
  font-weight: 500;
}
.cta__points i { color: var(--color-accent); }

.cta__qr {
  background: var(--color-bg-alt);
  border-radius: var(--radius-lg);
  padding: 28px;
  text-align: center;
  box-shadow: var(--shadow-lg);
}
.cta__qr img {
  width: 200px;
  height: 200px;
  margin: 0 auto 12px;
  border-radius: var(--radius-sm);
}
.cta__qr p {
  margin: 0;
  font-size: 14px;
  color: var(--color-primary);
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.cta__qr i { color: var(--color-accent); font-size: 16px; }

/* ---------- Footer ---------- */
.footer {
  background: #142438;
  color: rgba(255, 255, 255, .7);
  padding: 64px 0 32px;
}
.footer__inner {
  display: grid;
  grid-template-columns: 1.2fr 1fr 1fr;
  gap: 48px;
  align-items: start;
}
.footer__brand {
  display: flex;
  align-items: center;
  gap: 14px;
}
.footer__brand p {
  margin: 0;
  font-size: 14px;
  color: rgba(255, 255, 255, .55);
}
.footer__logo {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-sm);
}
.footer__nav {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px 24px;
}
.footer__nav a {
  color: rgba(255, 255, 255, .7);
  font-size: 14px;
}
.footer__nav a:hover { color: var(--color-accent); }
.footer__meta {
  text-align: right;
  font-size: 13px;
  color: rgba(255, 255, 255, .55);
}
.footer__meta p { margin: 0 0 6px; }
.footer__beian { margin: 10px 0 0; line-height: 1.9; }
.footer__beian a {
  display: block;
  color: rgba(255, 255, 255, .45);
  font-size: 12px;
  text-decoration: none;
}
.footer__beian a:hover { color: var(--color-accent); }

/* ---------- 滚动渐入 ---------- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 700ms ease, transform 700ms cubic-bezier(.2, .7, .2, 1);
}
.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* 减少动画偏好 */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: .01ms !important;
    transition-duration: .01ms !important;
  }
  .reveal { opacity: 1; transform: none; }
}

/* ============================================================
   响应式
   ============================================================ */
@media (max-width: 1024px) {
  .hero__inner { grid-template-columns: 1fr; gap: 48px; }
  .hero { padding: 140px 0 80px; }
  .features { grid-template-columns: repeat(2, 1fr); }
  .features .card:last-child { grid-column: 1 / -1; }
  .steps { grid-template-columns: repeat(2, 1fr); gap: 32px 24px; }
  .steps::before { display: none; }
  .rules, .privacy { grid-template-columns: repeat(2, 1fr); }
  .rules .rule:last-child, .privacy .privacy__item:last-child { grid-column: 1 / -1; }
  .overview { grid-template-columns: 1fr; gap: 32px; }
  .cta__inner { grid-template-columns: 1fr; gap: 40px; text-align: center; }
  .cta__lede { margin-left: auto; margin-right: auto; }
  .footer__inner { grid-template-columns: 1fr 1fr; gap: 32px; }
  .footer__meta { grid-column: 1 / -1; text-align: left; }
}

@media (max-width: 768px) {
  .container { padding: 0 20px; }
  .section { padding: 80px 0; }
  .section__head { margin-bottom: 40px; }

  /* 导航变汉堡 */
  .nav__toggle { display: inline-flex; }
  .nav__menu {
    position: fixed;
    top: 72px;
    inset: 72px 0 auto 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 16px 20px 24px;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-divider);
    transform: translateY(-110%);
    transition: transform var(--transition);
    box-shadow: var(--shadow-md);
  }
  .nav__menu.is-open { transform: translateY(0); }
  .nav__link {
    padding: 14px 8px;
    border-bottom: 1px solid var(--color-divider);
    font-size: 16px;
  }
  .nav__link:last-child { border-bottom: 0; }
  .nav__link--cta { justify-content: center; margin-top: 12px; }

  /* Hero */
  .hero { padding: 110px 0 60px; text-align: center; }
  .hero__lede { font-size: 16px; margin-left: auto; margin-right: auto; }
  .hero__bullets { justify-content: center; flex-direction: column; gap: 12px; align-items: center; }
  .hero__card { padding: 28px; }
  .hero__qr { width: 200px; height: 200px; }
  .hero__scroll { display: none; }

  /* 全部单列 */
  .features, .steps, .rules, .privacy {
    grid-template-columns: 1fr;
  }
  .features .card:last-child,
  .rules .rule:last-child,
  .privacy .privacy__item:last-child {
    grid-column: auto;
  }

  .footer__inner { grid-template-columns: 1fr; }
  .footer__meta { text-align: left; }
}

@media (max-width: 480px) {
  .hero__title { font-size: 36px; }
  .section__title { font-size: 26px; }
  .card, .rule, .privacy__item { padding: 28px 24px; }
}