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

:root {
  --primary: #4A90D9;
  --primary-dark: #3A7BC8;
  --primary-light: #E8F2FC;
  --accent: #FF6B6B;
  --bg: #F5F7FA;
  --card-bg: #FFFFFF;
  --text: #333333;
  --text-light: #666666;
  --border: #E0E4E8;
  --shadow: 0 2px 12px rgba(0,0,0,0.08);
  --radius: 10px;
}

body {
  font-family: "Microsoft YaHei", "PingFang SC", "Helvetica Neue", Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a { color: var(--primary); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--primary-dark); }

/* ===== 顶部导航 ===== */
.site-header {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: #fff;
  padding: 16px 0;
  box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}
.site-header .header-inner {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
}
.site-header .logo {
  font-size: 22px;
  font-weight: bold;
  color: #fff;
}
.site-header .logo span { opacity: 0.8; font-size: 14px; font-weight: normal; margin-left: 8px; }
.site-header nav a {
  color: rgba(255,255,255,0.85);
  margin-left: 18px;
  font-size: 14px;
}
.site-header nav a:hover { color: #fff; }

/* ===== 主内容容器 ===== */
.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 30px 20px;
  flex: 1;
}

/* ===== 面包屑 ===== */
.breadcrumb {
  font-size: 13px;
  color: var(--text-light);
  margin-bottom: 16px;
}
.breadcrumb a { color: var(--text-light); }
.breadcrumb a:hover { color: var(--primary); }
.breadcrumb .sep { margin: 0 6px; }

/* ===== 工具标题 ===== */
.tool-title {
  text-align: center;
  font-size: 26px;
  font-weight: bold;
  color: var(--text);
  margin-bottom: 6px;
}
.tool-subtitle {
  text-align: center;
  font-size: 14px;
  color: var(--text-light);
  margin-bottom: 24px;
}

/* ===== 工具卡片容器 ===== */
.tool-box {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 30px;
  margin-bottom: 24px;
}

/* ===== 主页工具网格 ===== */
.category-section {
  margin-bottom: 36px;
}
.category-section h2 {
  font-size: 20px;
  color: var(--text);
  margin-bottom: 16px;
  padding-left: 12px;
  border-left: 4px solid var(--primary);
}
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 16px;
}
.tool-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px;
  text-align: center;
  transition: transform 0.2s, box-shadow 0.2s;
  cursor: pointer;
  display: block;
  color: var(--text);
}
.tool-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 4px 20px rgba(0,0,0,0.12);
  color: var(--primary);
}
.tool-card .icon {
  font-size: 32px;
  margin-bottom: 10px;
  display: block;
}
.tool-card .name {
  font-size: 15px;
  font-weight: bold;
  margin-bottom: 4px;
}
.tool-card .desc {
  font-size: 12px;
  color: var(--text-light);
}

/* ===== 通用表单 ===== */
input[type="text"], input[type="number"], select, textarea {
  width: 100%;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 15px;
  outline: none;
  transition: border-color 0.2s;
  font-family: inherit;
}
input:focus, select:focus, textarea:focus { border-color: var(--primary); }
label { font-size: 14px; color: var(--text-light); display: block; margin-bottom: 5px; }

/* ===== 按钮 ===== */
.btn {
  display: inline-block;
  padding: 10px 24px;
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 6px;
  font-size: 15px;
  cursor: pointer;
  transition: background 0.2s;
  font-family: inherit;
}
.btn:hover { background: var(--primary-dark); }
.btn-secondary { background: #999; }
.btn-secondary:hover { background: #777; }
.btn-accent { background: var(--accent); }
.btn-accent:hover { background: #e85555; }

/* ===== 计算器专用样式 ===== */
.calc-display {
  width: 100%;
  height: 60px;
  font-size: 28px;
  text-align: right;
  padding: 0 16px;
  border: 2px solid var(--border);
  border-radius: 8px;
  margin-bottom: 12px;
  background: #f9f9f9;
  font-family: "Consolas", monospace;
}
.calc-keys {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
}
.calc-keys button {
  padding: 16px 0;
  font-size: 18px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #fff;
  cursor: pointer;
  transition: background 0.15s;
  font-family: inherit;
}
.calc-keys button:hover { background: var(--primary-light); }
.calc-keys button.op { background: var(--primary); color: #fff; border-color: var(--primary); }
.calc-keys button.op:hover { background: var(--primary-dark); }
.calc-keys button.eq { background: var(--accent); color: #fff; border-color: var(--accent); }
.calc-keys button.eq:hover { background: #e85555; }
.calc-keys button.fn { background: #f0f4f8; font-size: 14px; }
.calc-keys button.span2 { grid-column: span 2; }

/* 科学计算器切换 */
.calc-tabs {
  display: flex;
  gap: 0;
  margin-bottom: 16px;
  border-bottom: 2px solid var(--border);
}
.calc-tabs button {
  padding: 10px 20px;
  border: none;
  background: none;
  cursor: pointer;
  font-size: 15px;
  color: var(--text-light);
  border-bottom: 3px solid transparent;
  margin-bottom: -2px;
  font-family: inherit;
}
.calc-tabs button.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
  font-weight: bold;
}
.calc-panel { display: none; }
.calc-panel.active { display: block; }

/* 科学计算器按键 */
.calc-keys-sci {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 6px;
}
.calc-keys-sci button {
  padding: 12px 0;
  font-size: 14px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: #fff;
  cursor: pointer;
  transition: background 0.15s;
  font-family: inherit;
}
.calc-keys-sci button:hover { background: var(--primary-light); }
.calc-keys-sci button.op { background: var(--primary); color: #fff; border-color: var(--primary); }
.calc-keys-sci button.fn { background: #f0f4f8; font-size: 13px; }

/* ===== 换算工具样式 ===== */
.converter-row {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: end;
  margin-bottom: 20px;
}
.converter-row .swap-btn {
  padding: 10px 14px;
  background: var(--primary-light);
  border: 1px solid var(--primary);
  color: var(--primary);
  border-radius: 6px;
  cursor: pointer;
  font-size: 18px;
  white-space: nowrap;
  font-family: inherit;
  margin-bottom: 0;
}
.converter-row .swap-btn:hover { background: var(--primary); color: #fff; }

.convert-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 16px;
}
.convert-table th, .convert-table td {
  padding: 8px 12px;
  border: 1px solid var(--border);
  text-align: left;
  font-size: 14px;
}
.convert-table th { background: var(--primary-light); color: var(--primary-dark); font-weight: bold; }
.convert-table td:first-child { font-weight: bold; width: 120px; }
.convert-table input { padding: 6px 10px; font-size: 14px; }

/* ===== 结果显示 ===== */
.result-box {
  background: var(--primary-light);
  border: 1px solid var(--primary);
  border-radius: 8px;
  padding: 16px 20px;
  margin-top: 16px;
  font-size: 16px;
}
.result-box .label { color: var(--text-light); font-size: 13px; }
.result-box .value { font-size: 22px; font-weight: bold; color: var(--primary-dark); }

/* ===== 相关工具 ===== */
.related-tools {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px 24px;
  margin-bottom: 24px;
}
.related-tools h3 {
  font-size: 16px;
  margin-bottom: 12px;
  color: var(--text);
}
.related-tools .links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.related-tools .links a {
  display: inline-block;
  padding: 6px 14px;
  background: var(--primary-light);
  border-radius: 20px;
  font-size: 13px;
  color: var(--primary-dark);
  transition: background 0.2s;
}
.related-tools .links a:hover { background: var(--primary); color: #fff; }

/* ===== 说明文字 ===== */
.tool-desc {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px;
  font-size: 14px;
  color: var(--text-light);
  line-height: 1.8;
}
.tool-desc h3 { color: var(--text); font-size: 16px; margin: 12px 0 6px; }
.tool-desc p { margin-bottom: 10px; }

/* ===== 页脚 ===== */
.site-footer {
  background: #2c3e50;
  color: rgba(255,255,255,0.7);
  text-align: center;
  padding: 24px 20px;
  font-size: 13px;
  margin-top: auto;
}
.site-footer a { color: rgba(255,255,255,0.8); }
.site-footer p { margin-bottom: 5px; }

/* ===== 响应式 ===== */
@media (max-width: 600px) {
  .converter-row { grid-template-columns: 1fr; }
  .converter-row .swap-btn { justify-self: center; }
  .calc-keys-sci { grid-template-columns: repeat(4, 1fr); }
  .tool-grid { grid-template-columns: repeat(2, 1fr); }
}