/* ============================================
   木姜子科技工作室 Litsea Tech Studio
   全局样式表 — 黑白简约 · 锐利编辑风
   ============================================ */

/* ---------- 字体 ---------- */
@import url('https://fonts.googleapis.com/css2?family=Noto+Serif+SC:wght@500;700&display=swap');

/* ---------- 设计令牌 ---------- */
:root {
  /* 黑白主色系 —— 中性主导 */
  --color-bg: #FFFFFF;
  --color-surface: #FAFAFA;
  --color-surface-2: #F5F5F5;
  --color-text: #0A0A0A;
  --color-text-secondary: #3A3A3A;
  --color-text-muted: #8A8A8A;
  --color-border: #E5E5E5;
  --color-border-strong: #1A1A1A;
  --color-shadow: rgba(0, 0, 0, 0.03);

  /* 点缀 —— 炭黑（链接/hover/active） */
  --color-accent: #1A1A1A;
  --color-accent-soft: #F0F0F0;

  /* 占位灰度档（作品卡极淡差异） */
  --shade-1: #F5F5F5;
  --shade-2: #EFEFEF;
  --shade-3: #E9E9E9;
  --shade-4: #E3E3E3;
  --shade-5: #DDDDDD;
  --shade-6: #D7D7D7;

  /* 圆角 —— 近直角 */
  --radius-sm: 2px;
  --radius-md: 3px;
  --radius-lg: 4px;
  --radius-xl: 6px;

  /* 过渡 */
  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-medium: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.4s cubic-bezier(0.4, 0, 0.2, 1);

  /* 间距 */
  --section-gap: 120px;
  --container-max: 1120px;

  /* 字体族 */
  --font-serif: "Noto Serif SC", "Songti SC", "STSong", "SimSun", serif;
  --font-sans: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
}

/* ---------- 全局重置 ---------- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
  overflow-x: hidden;
}

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

a {
  color: var(--color-text);
  text-decoration: none;
  transition: color var(--transition-fast), opacity var(--transition-fast);
}

a:hover {
  color: var(--color-accent);
}

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

.container--narrow {
  max-width: 800px;
}

/* ---------- 导航栏 ---------- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 20px 0;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition-fast), padding var(--transition-fast);
}

.nav--scrolled {
  border-bottom-color: var(--color-border);
  padding: 14px 0;
}

.nav__inner {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav__logo {
  font-family: var(--font-serif);
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: 0.04em;
  display: flex;
  align-items: center;
  gap: 10px;
}

.nav__logo-icon {
  width: 28px;
  height: 28px;
  border-radius: var(--radius-sm);
  background: var(--color-text);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: 0.75rem;
}

.nav__links {
  display: flex;
  align-items: center;
  gap: 40px;
  list-style: none;
}

.nav__item {
  position: relative;
}

.nav__link {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  font-weight: 500;
  position: relative;
  padding: 4px 0;
  transition: color var(--transition-fast);
}

.nav__link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--color-text);
  transition: width var(--transition-fast);
}

.nav__link:hover,
.nav__link--active {
  color: var(--color-text);
}

.nav__link:hover::after,
.nav__link--active::after {
  width: 100%;
}

.nav__submenu {
  position: absolute;
  top: calc(100% + 10px);
  left: 50%;
  transform: translateX(-50%) translateY(-4px);
  min-width: 112px;
  padding: 8px;
  list-style: none;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  box-shadow: 0 12px 28px var(--color-shadow);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-fast), transform var(--transition-fast);
}

.nav__item:hover .nav__submenu,
.nav__item:focus-within .nav__submenu {
  opacity: 1;
  pointer-events: auto;
  transform: translateX(-50%) translateY(0);
}

.nav__sublink {
  display: block;
  padding: 8px 10px;
  color: var(--color-text-secondary);
  font-size: 0.84rem;
  white-space: nowrap;
  border-radius: var(--radius-sm);
  transition: background var(--transition-fast), color var(--transition-fast);
}

.nav__sublink:hover,
.nav__sublink--active {
  color: var(--color-text);
  background: var(--color-surface-2);
}

/* 移动端汉堡菜单 */
.nav__toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  background: none;
  border: none;
  padding: 4px;
}

.nav__toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text);
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 28px;
  font-size: 0.9rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  border: 1px solid transparent;
  font-family: inherit;
  line-height: 1.4;
  letter-spacing: 0.02em;
}

.btn--primary {
  background: var(--color-text);
  color: #fff;
  border-color: var(--color-text);
}

.btn--primary:hover {
  background: transparent;
  color: var(--color-text);
}

.btn--outline {
  background: transparent;
  color: var(--color-text);
  border-color: var(--color-text);
}

.btn--outline:hover {
  background: var(--color-text);
  color: #fff;
}

/* ---------- 区块标题 ---------- */
.section {
  padding: var(--section-gap) 0;
}

.section__label {
  font-family: var(--font-serif);
  font-size: 0.8rem;
  font-weight: 500;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.section__label::before {
  content: '';
  display: inline-block;
  width: 24px;
  height: 1px;
  background: var(--color-text-muted);
}

.section__title {
  font-family: var(--font-serif);
  font-size: 2.6rem;
  font-weight: 700;
  color: var(--color-text);
  line-height: 1.25;
  margin-bottom: 20px;
  letter-spacing: -0.01em;
}

.section__desc {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  max-width: 600px;
  line-height: 1.8;
}

.section__header {
  text-align: center;
  margin-bottom: 72px;
}

.section__header .section__label {
  justify-content: center;
}

.section__header .section__desc {
  margin: 0 auto;
}

/* ---------- 卡片基础 ---------- */
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 40px 32px;
  transition: border-color var(--transition-medium), transform var(--transition-medium);
}

.card:hover {
  border-color: var(--color-text);
  transform: translateY(-2px);
}

/* ---------- 网格 ---------- */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 32px;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

/* ---------- 图标（装饰性） ---------- */
.icon-circle {
  width: 56px;
  height: 56px;
  border-radius: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.icon-circle--green,
.icon-circle--warm {
  background: var(--color-surface-2);
  color: var(--color-text);
}

/* ---------- 标签 ---------- */
.tag {
  display: inline-block;
  padding: 4px 12px;
  font-size: 0.75rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  letter-spacing: 0.04em;
}

.tag--active {
  background: var(--color-text);
  color: #fff;
  border-color: var(--color-text);
}

/* ---------- 页脚 ---------- */
.footer {
  background: var(--color-bg);
  border-top: 1px solid var(--color-border);
  padding: 48px 0;
}

.footer__inner {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 20px;
}

.footer__brand {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
}

.footer__links {
  display: flex;
  align-items: center;
  gap: 24px;
}

.footer__link {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
}

.footer__link:hover {
  color: var(--color-text);
}

.footer__social {
  display: flex;
  gap: 12px;
}

.footer__social-icon {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: transparent;
  border: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
  font-size: 0.85rem;
}

.footer__social-icon:hover {
  background: var(--color-text);
  color: #fff;
  border-color: var(--color-text);
}

/* ---------- 动效系统 ---------- */

/* 初始隐藏状态 */
.fade-in-up {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s cubic-bezier(0.4, 0, 0.2, 1),
              transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

.fade-in-left {
  opacity: 0;
  transform: translateX(-20px);
  transition: opacity 0.6s cubic-bezier(0.4, 0, 0.2, 1),
              transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

.fade-in-right {
  opacity: 0;
  transform: translateX(20px);
  transition: opacity 0.6s cubic-bezier(0.4, 0, 0.2, 1),
              transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 可见状态 */
.fade-in-up.visible,
.fade-in-left.visible,
.fade-in-right.visible {
  opacity: 1;
  transform: translate(0, 0);
}

/* 交错延迟 */
.delay-100 { transition-delay: 0.10s; }
.delay-200 { transition-delay: 0.20s; }
.delay-300 { transition-delay: 0.30s; }
.delay-400 { transition-delay: 0.40s; }
.delay-500 { transition-delay: 0.50s; }
.delay-600 { transition-delay: 0.60s; }

/* 淡入缩放 */
.fade-in-scale {
  opacity: 0;
  transform: scale(0.96);
  transition: opacity 0.5s cubic-bezier(0.4, 0, 0.2, 1),
              transform 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.fade-in-scale.visible {
  opacity: 1;
  transform: scale(1);
}

/* ============================================
   响应式设计
   ============================================ */

@media (max-width: 900px) {
  :root {
    --section-gap: 72px;
  }

  .container {
    padding: 0 20px;
  }

  .section__title {
    font-size: 1.9rem;
  }

  .section__desc {
    font-size: 1rem;
  }

  .grid-2,
  .grid-3 {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .nav__links {
    position: fixed;
    top: 0;
    right: -100%;
    width: 260px;
    height: 100vh;
    background: var(--color-bg);
    flex-direction: column;
    padding: 80px 32px 32px;
    gap: 24px;
    box-shadow: -4px 0 24px var(--color-shadow);
    border-left: 1px solid var(--color-border);
    transition: right var(--transition-medium);
    z-index: 999;
  }

  .nav__item {
    width: 100%;
  }

  .nav__submenu {
    position: static;
    transform: none;
    min-width: 0;
    margin-top: 10px;
    padding: 0 0 0 14px;
    border: 0;
    box-shadow: none;
    background: transparent;
    opacity: 1;
    pointer-events: auto;
  }

  .nav__item:hover .nav__submenu,
  .nav__item:focus-within .nav__submenu {
    transform: none;
  }

  .nav__links--open {
    right: 0;
  }

  .nav__toggle {
    display: flex;
    z-index: 1000;
  }

  .nav__inner {
    padding: 0 20px;
  }

  .footer__inner {
    padding: 0 20px;
    flex-direction: column;
    text-align: center;
    gap: 16px;
  }
}

@media (max-width: 600px) {
  .section__title {
    font-size: 1.6rem;
  }

  .btn {
    padding: 12px 22px;
    font-size: 0.85rem;
  }

  .card {
    padding: 28px 22px;
  }
}