/* 网球技术知识站 —— 样式表（不引用任何外部字体/CDN，国内加载稳定） */
:root {
  --ink: #16221c;
  --ink-soft: #4a5a52;
  --muted: #7c8b83;
  --line: #e2e8e3;
  --bg: #f6f8f6;
  --white: #ffffff;
  --green: #1f7a4d;
  --green-dark: #145636;
  --green-soft: #eaf4ee;
  --clay: #b4643c;
  --clay-soft: #fbf1ea;
  --radius: 10px;
  --shadow: 0 1px 2px rgba(22, 34, 28, .05), 0 8px 24px rgba(22, 34, 28, .05);
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.75 -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei",
        "PingFang SC", "Hiragino Sans GB", sans-serif;
}

a { color: var(--green); text-decoration: none; }
a:hover { text-decoration: underline; }

.wrap { max-width: 1040px; margin: 0 auto; padding: 0 22px; }

/* ---------- 顶栏 ---------- */
.topbar {
  background: var(--white);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 10;
}
.topbar .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  min-height: 62px;
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; letter-spacing: .3px; }
.brand:hover { text-decoration: none; }
.brand .ball {
  width: 26px; height: 26px; border-radius: 50%;
  background: radial-gradient(circle at 32% 30%, #d8f06a, #a8c93a 62%, #7fa021);
  box-shadow: inset -2px -3px 6px rgba(0, 0, 0, .18);
  flex: none;
}
.brand small { display: block; font-weight: 400; font-size: 11px; color: var(--muted); letter-spacing: .5px; }
nav { display: flex; flex-wrap: wrap; gap: 4px 18px; font-size: 15px; }
nav a { color: var(--ink-soft); padding: 6px 0; }
nav a[aria-current="page"] { color: var(--green); font-weight: 600; border-bottom: 2px solid var(--green); }

/* ---------- 页头 ---------- */
.hero {
  background: linear-gradient(160deg, #f2f7f3 0%, #ffffff 55%, var(--clay-soft) 100%);
  border-bottom: 1px solid var(--line);
  padding: 54px 0 46px;
}
.hero h1 { margin: 0 0 14px; font-size: 30px; line-height: 1.35; letter-spacing: .2px; }
.hero p { margin: 0; max-width: 720px; color: var(--ink-soft); font-size: 17px; }
.hero .kicker {
  display: inline-block; margin-bottom: 14px; padding: 3px 10px; border-radius: 999px;
  background: var(--green-soft); color: var(--green); font-size: 12px; letter-spacing: 1px;
}

/* ---------- 内容 ---------- */
main { padding: 40px 0 56px; }
section + section { margin-top: 38px; }
h2 { font-size: 21px; margin: 0 0 12px; letter-spacing: .2px; }
h3 { font-size: 17px; margin: 22px 0 8px; }
h4 { font-size: 15px; margin: 16px 0 6px; color: var(--ink-soft); }
p { margin: 0 0 12px; }
ul, ol { margin: 0 0 12px; padding-left: 22px; }
li { margin: 5px 0; }
code {
  background: #eef2ef; border: 1px solid var(--line); border-radius: 4px;
  padding: 1px 5px; font-size: 13.5px;
}

.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(232px, 1fr)); gap: 16px; }
.card {
  background: var(--white); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 18px 18px 16px; box-shadow: var(--shadow);
}
.card h3 { margin: 0 0 6px; font-size: 16px; }
.card p { margin: 0; color: var(--ink-soft); font-size: 14.5px; }
.card .tag {
  display: inline-block; margin-bottom: 8px; font-size: 11px; letter-spacing: .6px;
  color: var(--green); background: var(--green-soft); border-radius: 999px; padding: 2px 9px;
}

.notice {
  background: var(--clay-soft); border: 1px solid #f0dccd; border-left: 4px solid var(--clay);
  border-radius: 6px; padding: 14px 16px; color: #6c4530; font-size: 14.5px;
}
.notice strong { color: #5a3826; }

table { width: 100%; border-collapse: collapse; background: var(--white); font-size: 14.5px; }
caption { text-align: left; color: var(--muted); font-size: 13px; padding-bottom: 8px; }
th, td { border: 1px solid var(--line); padding: 9px 11px; text-align: left; vertical-align: top; }
th { background: #f3f6f4; font-weight: 600; }

.toc { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 10px; padding: 0; list-style: none; }
.toc li { margin: 0; }
.toc a {
  display: block; background: var(--white); border: 1px solid var(--line);
  border-radius: 8px; padding: 11px 13px; color: var(--ink-soft); font-size: 14.5px;
}
.toc a:hover { border-color: #c9dccf; color: var(--green); text-decoration: none; }

/* ---------- 页脚 ---------- */
footer {
  border-top: 1px solid var(--line); background: var(--white);
  padding: 26px 0 34px; color: var(--muted); font-size: 13px;
}
footer .rows { display: flex; flex-wrap: wrap; gap: 6px 20px; align-items: baseline; }
footer a { color: var(--muted); }
footer .disclaimer { margin-top: 10px; max-width: 760px; line-height: 1.7; }

@media (max-width: 720px) {
  .hero { padding: 38px 0 32px; }
  .hero h1 { font-size: 24px; }
  .topbar .wrap { flex-direction: column; align-items: flex-start; gap: 4px; padding-top: 10px; padding-bottom: 10px; }
  nav { font-size: 14px; gap: 4px 14px; }
  main { padding: 28px 0 40px; }
  table { font-size: 13.5px; }
  th, td { padding: 7px 8px; }
}