/* =========================================================
   设计语言：Apple 设计系统（来自 design.md）
   - 干净留白、单一蓝色强调、明暗交替大区块
   - 标题 600 字重 + 负字距；正文 17px；单一产品投影
   - 不使用装饰性渐变，氛围靠色块与几何图形
   ========================================================= */

:root {
  /* 颜色 */
  --blue: #0066cc;          /* Action Blue：唯一强调色 */
  --blue-focus: #0071e3;
  --blue-on-dark: #2997ff;
  --ink: #1d1d1f;           /* 近黑文字 */
  --body: #1d1d1f;
  --body-muted: #7a7a7a;    /* 次要文字 */
  --on-dark: #ffffff;
  --on-dark-muted: #cccccc;
  --canvas: #ffffff;        /* 主画布 */
  --parchment: #f5f5f7;     /* 米白交替区块 */
  --tile-1: #272729;        /* 近黑区块 */
  --tile-2: #2a2a2c;
  --hairline: #e0e0e0;

  /* 间距（8px 基准） */
  --s-xs: 8px; --s-sm: 12px; --s-md: 17px; --s-lg: 24px;
  --s-xl: 32px; --s-xxl: 48px; --s-section: 80px;

  /* 圆角 */
  --r-sm: 8px; --r-lg: 18px; --r-pill: 9999px;

  /* 唯一产品投影 */
  --product-shadow: rgba(0, 0, 0, 0.22) 3px 5px 30px;

  /* 字体 */
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
          "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.47;
  letter-spacing: -0.374px;
  color: var(--body);
  background: var(--canvas);
  -webkit-font-smoothing: antialiased;
}

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

.container {
  width: 100%;
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 var(--s-lg);
}

/* ===== 导航（磨砂半透明） ===== */
.nav {
  position: sticky; top: 0; z-index: 50;
  background: rgba(245, 245, 247, 0.8);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--hairline);
}
.nav-inner {
  max-width: 1080px; margin: 0 auto;
  height: 52px; padding: 0 var(--s-lg);
  display: flex; align-items: center; justify-content: space-between;
}
.nav-brand {
  font-size: 17px; font-weight: 600; color: var(--ink);
  text-decoration: none; letter-spacing: -0.2px;
}
.nav-links { display: flex; align-items: center; gap: var(--s-lg); }
.nav-links a {
  font-size: 14px; color: var(--ink); text-decoration: none;
  letter-spacing: -0.2px; opacity: 0.85; transition: opacity .2s;
}
.nav-links a:hover { opacity: 1; }
.nav-cta {
  color: var(--blue) !important; font-weight: 600;
}
.nav-toggle {
  display: none; flex-direction: column; gap: 5px;
  background: none; border: 0; cursor: pointer; padding: 8px;
}
.nav-toggle span {
  width: 22px; height: 2px; background: var(--ink); border-radius: 2px;
  transition: transform .25s, opacity .25s;
}

/* ===== 按钮 ===== */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  min-height: 44px; padding: 11px 22px;
  font-size: 17px; text-decoration: none; cursor: pointer;
  border-radius: var(--r-pill); border: 0;
  transition: transform .12s ease, background .2s ease;
}
.btn:active { transform: scale(0.95); }
.btn-primary { background: var(--blue); color: #fff; }
.btn-primary:hover { background: var(--blue-focus); }
.btn-ghost {
  background: transparent; color: var(--blue);
  border: 1px solid var(--blue);
}
.btn-ghost:hover { background: rgba(0, 102, 204, 0.06); }

.text-link {
  color: var(--blue); text-decoration: none; font-weight: 600;
  font-size: 15px; letter-spacing: -0.2px;
}
.text-link:hover { text-decoration: underline; }

/* ===== 首屏 ===== */
.hero { padding: clamp(56px, 9vw, var(--s-section)) 0; }
.hero-grid {
  display: grid; grid-template-columns: 1.1fr 0.9fr;
  gap: var(--s-xxl); align-items: center;
}
.eyebrow {
  font-size: 13px; font-weight: 600; letter-spacing: 0.5px;
  text-transform: uppercase; color: var(--blue); margin-bottom: var(--s-md);
}
.hero h1 {
  font-size: clamp(40px, 6vw, 56px); font-weight: 600;
  line-height: 1.07; letter-spacing: -0.28px; color: var(--ink);
}
.hero .lead {
  font-size: clamp(19px, 2.4vw, 24px); font-weight: 300;
  line-height: 1.5; color: var(--body); margin: var(--s-lg) 0 var(--s-xl);
  max-width: 30ch;
}
.hero-actions { display: flex; gap: var(--s-sm); flex-wrap: wrap; }

/* 首屏视觉：装饰性窗口 */
.hero-visual { display: flex; justify-content: center; }
.visual-window {
  width: 100%; max-width: 380px; background: var(--parchment);
  border-radius: var(--r-lg); padding: var(--s-md);
  box-shadow: var(--product-shadow);
}
.visual-bar { display: flex; gap: 6px; margin-bottom: var(--s-md); }
.visual-bar span {
  width: 10px; height: 10px; border-radius: 50%; background: var(--hairline);
}
.visual-body { background: var(--canvas); border-radius: var(--r-sm); padding: var(--s-lg); }
.visual-dot {
  display: block; width: 56px; height: 56px; border-radius: var(--r-pill);
  background: var(--blue); margin: 0 auto var(--s-md);
}
.visual-line {
  display: block; height: 10px; border-radius: var(--r-pill);
  background: var(--parchment); margin: var(--s-sm) 0;
}
.visual-line.short { width: 60%; }

/* ===== 通用区块 ===== */
.section { padding: var(--s-section) 0; }
.section-parchment { background: var(--parchment); }
.section-dark { background: var(--tile-1); }
.section-title {
  font-size: clamp(30px, 4.4vw, 40px); font-weight: 600;
  letter-spacing: -0.3px; color: var(--ink); line-height: 1.1;
}
.center { text-align: center; }
.center-text { text-align: center; }
.eyebrow.center { display: block; }
.section-title.center { margin: var(--s-sm) auto var(--s-xl); }
.section-title.light, .eyebrow.light, .lead.light { color: var(--on-dark); }
.eyebrow.light { color: var(--blue-on-dark); }
.lead.light { color: var(--on-dark-muted); opacity: 0.92; }
.lead { font-size: 21px; font-weight: 300; line-height: 1.5; }
.lead.light { max-width: 46ch; margin: var(--s-lg) auto var(--s-xl); }

/* ===== 能力卡片 ===== */
.card-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--s-lg);
}
.card {
  background: var(--canvas); border: 1px solid var(--hairline);
  border-radius: var(--r-lg); padding: var(--s-lg);
  transition: transform .2s ease;
}
.card:hover { transform: translateY(-4px); }
.card-icon {
  width: 44px; height: 44px; border-radius: var(--r-pill);
  background: rgba(0, 102, 204, 0.08); color: var(--blue);
  display: flex; align-items: center; justify-content: center; margin-bottom: var(--s-md);
}
.card-icon svg { width: 22px; height: 22px; }
.card h3 { font-size: 19px; font-weight: 600; letter-spacing: -0.2px; margin-bottom: var(--s-xs); }
.card p { font-size: 15px; color: var(--body-muted); line-height: 1.5; }

/* ===== 作品 ===== */
.work-grid {
  display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--s-xl);
}
.work {
  background: var(--canvas); border: 1px solid var(--hairline);
  border-radius: var(--r-lg); overflow: hidden;
  transition: transform .2s ease;
}
.work:hover { transform: translateY(-4px); }
.work-thumb {
  aspect-ratio: 16 / 10; background: var(--parchment);
  display: flex; align-items: center; justify-content: center;
  box-shadow: var(--product-shadow);
}
.work-thumb.alt { background: var(--tile-1); }
.thumb-label {
  font-size: 13px; letter-spacing: 1px; color: var(--body-muted);
  border: 1px dashed var(--hairline); border-radius: var(--r-pill);
  padding: 4px 14px;
}
.work-thumb.alt .thumb-label { color: var(--on-dark-muted); border-color: #444; }
.work-meta { padding: var(--s-lg); }
.work-meta h3 { font-size: 20px; font-weight: 600; letter-spacing: -0.2px; margin-bottom: var(--s-xs); }
.work-meta p { font-size: 15px; color: var(--body-muted); margin-bottom: var(--s-sm); }

/* ===== 关于我 ===== */
.about-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: var(--s-xxl); align-items: center;
}
.body-text { font-size: 19px; font-weight: 300; line-height: 1.6; color: var(--body); margin-top: var(--s-md); }
.process { display: flex; flex-direction: column; gap: var(--s-lg); }
.step { display: flex; gap: var(--s-md); align-items: flex-start; }
.step-num {
  flex: 0 0 auto; width: 36px; height: 36px; border-radius: var(--r-pill);
  background: var(--blue); color: #fff; font-weight: 600;
  display: flex; align-items: center; justify-content: center;
}
.step h4 { font-size: 18px; font-weight: 600; letter-spacing: -0.2px; }
.step p { font-size: 15px; color: var(--body-muted); }

/* ===== 页脚 ===== */
.footer { background: var(--parchment); padding: var(--s-xl) 0 var(--s-lg); }
.footer-inner {
  display: flex; align-items: center; justify-content: space-between;
  gap: var(--s-lg); flex-wrap: wrap;
}
.footer-brand { font-size: 17px; font-weight: 600; color: var(--ink); }
.footer-links { display: flex; gap: var(--s-lg); }
.footer-links a, .footer-mail {
  font-size: 14px; color: var(--body-muted); text-decoration: none;
}
.footer-links a:hover, .footer-mail:hover { color: var(--ink); }
.footer-legal {
  margin-top: var(--s-lg); font-size: 12px; color: var(--body-muted);
  border-top: 1px solid var(--hairline); padding-top: var(--s-md);
}

/* ===== 进场动效 ===== */
.reveal { opacity: 0; transform: translateY(16px); transition: opacity .6s ease, transform .6s ease; }
.reveal.in { opacity: 1; transform: none; }

/* ===== 响应式 ===== */
@media (max-width: 900px) {
  .card-grid { grid-template-columns: repeat(2, 1fr); }
  .hero-grid { grid-template-columns: 1fr; gap: var(--s-xl); }
  .hero-visual { order: -1; }
  .about-grid { grid-template-columns: 1fr; gap: var(--s-xl); }
}
@media (max-width: 640px) {
  .nav-links {
    position: absolute; top: 52px; left: 0; right: 0;
    flex-direction: column; align-items: flex-start; gap: 0;
    background: rgba(245, 245, 247, 0.97);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--hairline);
    padding: var(--s-sm) var(--s-lg); display: none;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: var(--s-sm) 0; width: 100%; font-size: 17px; }
  .nav-toggle { display: flex; }
  .card-grid { grid-template-columns: 1fr; }
  .work-grid { grid-template-columns: 1fr; }
  .section { padding: 56px 0; }
}

@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  html { scroll-behavior: auto; }
  .btn:active, .card:hover, .work:hover { transform: none; }
}