:root {
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --bg: #f8fafc;
  --card-bg: #ffffff;
  --text: #1e293b;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --success: #10b981;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 4px 12px rgba(0, 0, 0, 0.1);
  --radius: 8px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "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;
}

a:hover {
  text-decoration: underline;
}

/* Header */
.site-header {
  background: var(--card-bg);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow);
}

.header-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 18px;
  font-weight: 700;
  color: var(--text);
  text-decoration: none;
}

.site-logo:hover {
  text-decoration: none;
}

.site-logo .icon {
  width: 32px;
  height: 32px;
  background: var(--primary);
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: 16px;
}

.nav-links {
  display: flex;
  gap: 24px;
  list-style: none;
}

.nav-links a {
  color: var(--text-muted);
  font-size: 14px;
  font-weight: 500;
  text-decoration: none;
  transition: color 0.2s;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--primary);
  text-decoration: none;
}

/* Main */
.main-content {
  flex: 1;
  max-width: 1200px;
  margin: 0 auto;
  padding: 32px 24px;
  width: 100%;
}

/* Hero */
.hero {
  text-align: center;
  padding: 48px 0 40px;
}

.hero h1 {
  font-size: 32px;
  font-weight: 800;
  margin-bottom: 12px;
  background: linear-gradient(135deg, var(--primary), #7c3aed);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  color: var(--text-muted);
  font-size: 16px;
  max-width: 600px;
  margin: 0 auto;
}

/* Tool Grid */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 20px;
  margin-top: 32px;
}

.tool-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  transition: all 0.2s;
  text-decoration: none;
  color: inherit;
  display: block;
}

.tool-card:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
  text-decoration: none;
}

.tool-card .tool-icon {
  width: 44px;
  height: 44px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 22px;
  margin-bottom: 14px;
}

.tool-card h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 6px;
}

.tool-card p {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.5;
}

/* Tool Page */
.tool-page {
  max-width: 800px;
  margin: 0 auto;
}

.tool-page-header {
  margin-bottom: 28px;
}

.tool-page-header h1 {
  font-size: 26px;
  font-weight: 700;
  margin-bottom: 8px;
}

.tool-page-header p {
  color: var(--text-muted);
  font-size: 14px;
}

.tool-panel {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow);
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text);
}

.form-group .hint {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 4px;
}

textarea,
input[type="text"],
input[type="number"],
select {
  width: 100%;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 14px;
  font-family: "SF Mono", "Fira Code", "Cascadia Code", monospace;
  transition: border-color 0.2s;
  background: #fff;
  color: var(--text);
}

textarea {
  min-height: 120px;
  resize: vertical;
}

textarea:focus,
input:focus,
select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.btn-row {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 16px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 18px;
  border: none;
  border-radius: 6px;
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
}

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

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

.btn-secondary {
  background: #f1f5f9;
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: #e2e8f0;
}

.result-box {
  margin-top: 20px;
  padding: 16px;
  background: #f1f5f9;
  border-radius: 6px;
  border: 1px solid var(--border);
  word-break: break-all;
  font-family: "SF Mono", "Fira Code", monospace;
  font-size: 13px;
  min-height: 48px;
  position: relative;
}

.result-box.empty {
  color: var(--text-muted);
  font-family: inherit;
}

.copy-btn {
  position: absolute;
  top: 8px;
  right: 8px;
  padding: 4px 10px;
  font-size: 12px;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 4px;
  cursor: pointer;
  color: var(--text-muted);
}

.copy-btn:hover {
  color: var(--primary);
  border-color: var(--primary);
}

/* Tabs */
.tabs {
  display: flex;
  gap: 0;
  border-bottom: 1px solid var(--border);
  margin-bottom: 24px;
}

.tab {
  padding: 10px 20px;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-muted);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: all 0.2s;
  background: none;
  border-top: none;
  border-left: none;
  border-right: none;
}

.tab:hover {
  color: var(--primary);
}

.tab.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
}

/* Info Page */
.info-page {
  max-width: 800px;
  margin: 0 auto;
}

.info-page h1 {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 24px;
}

.info-page h2 {
  font-size: 20px;
  font-weight: 600;
  margin: 28px 0 12px;
}

.info-page p,
.info-page li {
  color: var(--text-muted);
  font-size: 15px;
  margin-bottom: 12px;
}

.info-page ul {
  padding-left: 24px;
}

.info-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow);
}

/* Footer */
.site-footer {
  background: var(--card-bg);
  border-top: 1px solid var(--border);
  padding: 32px 24px;
  margin-top: auto;
}

.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 24px;
}

.footer-info {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 2;
}

.footer-links {
  display: flex;
  gap: 20px;
  list-style: none;
}

.footer-links a {
  font-size: 13px;
  color: var(--text-muted);
}

.footer-links a:hover {
  color: var(--primary);
}

.footer-bottom {
  max-width: 1200px;
  margin: 20px auto 0;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  text-align: center;
  font-size: 12px;
  color: var(--text-muted);
}

/* Toast */
.toast {
  position: fixed;
  bottom: 24px;
  right: 24px;
  background: var(--text);
  color: #fff;
  padding: 10px 20px;
  border-radius: 6px;
  font-size: 14px;
  opacity: 0;
  transform: translateY(10px);
  transition: all 0.3s;
  z-index: 1000;
  pointer-events: none;
}

.toast.show {
  opacity: 1;
  transform: translateY(0);
}

/* Responsive */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .hero h1 {
    font-size: 24px;
  }

  .tool-grid {
    grid-template-columns: 1fr;
  }

  .footer-inner {
    flex-direction: column;
  }
}