:root {
  --bg: #0b1220;
  --bg-soft: #0f172a;
  --surface: #1e293b;
  --surface-2: #26334d;
  --border: #334155;
  --text: #e2e8f0;
  --muted: #94a3b8;
  --primary: #38bdf8;
  --accent: #22d3ee;
  --ok: #34d399;
  --err: #f87171;
  --radius: 12px;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.25);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.container {
  width: 100%;
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ---------- 顶部导航 ---------- */
.site-header {
  background: rgba(15, 23, 42, 0.9);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
  flex-wrap: wrap;
}
.logo {
  font-size: 18px;
  font-weight: 700;
  color: var(--primary);
  text-decoration: none;
  letter-spacing: 0.5px;
}
.main-nav { display: flex; gap: 4px; flex-wrap: wrap; }
.main-nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
  padding: 6px 10px;
  border-radius: 8px;
  transition: all 0.2s;
}
.main-nav a:hover { color: var(--text); background: var(--surface-2); }
.main-nav a.active { color: var(--primary); background: rgba(56, 189, 248, 0.12); }

/* 汉堡菜单按钮（移动端） */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  padding: 9px;
}
.nav-toggle span {
  display: block;
  height: 2px;
  width: 100%;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.2s, opacity 0.2s;
}
.nav-toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.open span:nth-child(2) { opacity: 0; }
.nav-toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---------- 首页 Hero ---------- */
.hero {
  text-align: center;
  padding: 64px 0 40px;
  background:
    radial-gradient(600px 240px at 20% 0%, rgba(56, 189, 248, 0.14), transparent),
    radial-gradient(600px 240px at 80% 0%, rgba(34, 211, 238, 0.10), transparent);
}
.hero h1 {
  font-size: 42px;
  margin: 0 0 12px;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero p { color: var(--muted); font-size: 16px; margin: 0 0 28px; }
.search-box { max-width: 480px; margin: 0 auto; }
.search-box input {
  width: 100%;
  padding: 14px 18px;
  font-size: 15px;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 999px;
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s;
}
.search-box input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(56, 189, 248, 0.15);
}

/* ---------- 工具卡片 ---------- */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 16px;
  padding: 8px 0 56px;
}
.tool-card {
  display: block;
  text-decoration: none;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px 20px;
  transition: transform 0.2s, border-color 0.2s, box-shadow 0.2s;
}
.tool-card:hover {
  transform: translateY(-4px);
  border-color: var(--primary);
  box-shadow: var(--shadow);
}
.tool-icon { font-size: 32px; margin-bottom: 12px; }
.tool-card h2 { font-size: 18px; margin: 0 0 8px; color: var(--primary); }
.tool-card p { margin: 0; color: var(--muted); font-size: 14px; }
.tool-tag {
  display: inline-block;
  margin-top: 12px;
  font-size: 12px;
  color: var(--accent);
  border: 1px solid rgba(34, 211, 238, 0.4);
  border-radius: 999px;
  padding: 2px 10px;
}

.section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin: 28px 0 16px;
}
.section-title { margin: 0; font-size: 24px; }
.section-count { color: var(--muted); font-size: 13px; }

.empty-state {
  text-align: center;
  color: var(--muted);
  padding: 48px 0 72px;
  font-size: 15px;
}

/* ---------- 页脚 ---------- */
.site-footer {
  margin-top: auto;
  border-top: 1px solid var(--border);
  padding: 24px 0;
  text-align: center;
  color: var(--muted);
  font-size: 13px;
}

/* ---------- 工具页面 ---------- */
main { flex: 1; }
.tool-page { padding: 32px 0 56px; }
.back-link { color: var(--muted); text-decoration: none; font-size: 14px; }
.back-link:hover { color: var(--primary); }
.tool-header { margin-bottom: 24px; }
.tool-header h1 { margin: 8px 0 4px; font-size: 28px; }
.tool-header p { margin: 0; color: var(--muted); }

.tool-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 20px;
}
.form-group { margin-bottom: 16px; }
.form-group label,
.form-row label {
  display: block;
  font-size: 14px;
  color: var(--muted);
  margin-bottom: 6px;
}

textarea,
input[type="text"],
input[type="number"],
select {
  width: 100%;
  padding: 12px 14px;
  font-size: 14px;
  color: var(--text);
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: 8px;
  outline: none;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  resize: vertical;
  transition: border-color 0.2s, box-shadow 0.2s;
}
textarea { min-height: 120px; }
textarea:focus,
input:focus,
select:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(56, 189, 248, 0.15);
}
input[type="text"],
input[type="number"] { font-family: inherit; }
select { cursor: pointer; }
input[type="file"] {
  width: 100%;
  padding: 10px 14px;
  font-size: 14px;
  color: var(--text);
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: 8px;
  outline: none;
  cursor: pointer;
}
input[type="file"]::file-selector-button {
  margin-right: 12px;
  padding: 8px 14px;
  font-size: 13px;
  font-weight: 600;
  color: #06263b;
  background: var(--primary);
  border: none;
  border-radius: 6px;
  cursor: pointer;
}

.form-row {
  display: flex;
  align-items: flex-end;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}
.form-row .form-group { margin-bottom: 0; flex: 1; min-width: 140px; }

.btn {
  padding: 12px 22px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  background: var(--primary);
  color: #06263b;
  border: none;
  border-radius: 8px;
  transition: filter 0.2s, transform 0.1s;
  white-space: nowrap;
}
.btn:hover { filter: brightness(1.08); }
.btn:active { transform: translateY(1px); }
.btn-secondary {
  background: var(--surface-2);
  color: var(--text);
  border: 1px solid var(--border);
}
.btn-secondary:hover { border-color: var(--primary); filter: none; }

.output-wrap { position: relative; }
.copy-btn {
  position: absolute;
  top: 8px;
  right: 8px;
  font-size: 12px;
  cursor: pointer;
  background: var(--surface-2);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 4px 10px;
  transition: all 0.2s;
}
.copy-btn:hover { border-color: var(--primary); color: var(--primary); }
.copy-btn.copied { color: var(--ok); border-color: var(--ok); }

.status { font-size: 14px; margin: 8px 0 0; min-height: 20px; }
.result-ok { color: var(--ok); }
.result-err { color: var(--err); }

.result-value { font-size: 20px; font-weight: 700; color: var(--primary); margin: 4px 0 0; }
.result-sub { font-size: 14px; color: var(--muted); margin: 4px 0 0; }

.preset-row { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 16px; }
.preset-btn {
  font-size: 13px;
  cursor: pointer;
  padding: 6px 12px;
  border-radius: 999px;
  background: rgba(56, 189, 248, 0.1);
  color: var(--primary);
  border: 1px solid rgba(56, 189, 248, 0.35);
  transition: all 0.2s;
}
.preset-btn:hover { background: rgba(56, 189, 248, 0.2); }

.result-box {
  margin-top: 16px;
  padding: 16px 18px;
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: 8px;
}

/* ---------- 响应式 ---------- */
@media (max-width: 760px) {
  .nav-toggle { display: flex; }
  .header-inner { height: auto; padding: 10px 0; flex-wrap: wrap; justify-content: space-between; }
  .main-nav {
    display: none;
    width: 100%;
    flex-direction: column;
    gap: 2px;
    padding: 10px 0 4px;
  }
  .main-nav.open { display: flex; }
  .main-nav a { padding: 10px 12px; }
  .hero { padding: 44px 0 28px; }
  .hero h1 { font-size: 30px; }
  .tool-panel { padding: 18px; }
}