:root {
  --bg: #f7f8fa;
  --surface: #ffffff;
  --text: #111827;
  --text-secondary: #6b7280;
  --border: #e5e7eb;
  --primary: #059669;
  --primary-hover: #047857;
  --primary-soft: #ecfdf5;
  --danger: #dc2626;
  --danger-soft: #fef2f2;
  --success: #059669;
  --success-soft: #ecfdf5;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.04), 0 4px 12px rgba(0, 0, 0, 0.04);
  --radius: 10px;
  --font: "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --mono: "SF Mono", "Cascadia Code", "Consolas", "Liberation Mono", monospace;
  --nav-h: 56px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b1220;
    --surface: #111827;
    --text: #f3f4f6;
    --text-secondary: #9ca3af;
    --border: #1f2937;
    --primary: #34d399;
    --primary-hover: #6ee7b7;
    --primary-soft: #064e3b;
    --danger: #f87171;
    --danger-soft: #3f1515;
    --success: #34d399;
    --success-soft: #064e3b;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 8px 24px rgba(0, 0, 0, 0.25);
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

a {
  color: var(--primary);
  text-decoration: none;
}

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

.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 0 20px;
  background: color-mix(in srgb, var(--surface) 92%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.site-brand {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--text);
  font-weight: 800;
  font-size: 1.15rem;
  letter-spacing: -0.02em;
  flex-shrink: 0;
}

.site-brand:hover {
  color: var(--text);
}

.site-brand .mark {
  font-size: 1.35rem;
  line-height: 1;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-left: auto;
  overflow-x: auto;
}

.nav-links a {
  color: var(--text-secondary);
  font-size: 0.875rem;
  padding: 6px 10px;
  border-radius: 6px;
  white-space: nowrap;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--primary);
  background: var(--primary-soft);
}

.nav-dropdown {
  position: relative;
}

.nav-dropdown > button {
  appearance: none;
  border: 0;
  background: transparent;
  color: var(--text-secondary);
  font: inherit;
  font-size: 0.875rem;
  padding: 6px 10px;
  border-radius: 6px;
  cursor: pointer;
}

.nav-dropdown > button:hover,
.nav-dropdown.open > button {
  color: var(--primary);
  background: var(--primary-soft);
}

.nav-menu {
  display: none;
  position: absolute;
  right: 0;
  top: calc(100% + 6px);
  width: min(520px, calc(100vw - 24px));
  max-height: 70vh;
  overflow: auto;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 8px;
  grid-template-columns: 1fr 1fr;
  gap: 2px;
}

.nav-dropdown.open .nav-menu {
  display: grid;
}

.nav-menu a {
  display: block;
  padding: 8px 10px;
  border-radius: 6px;
  color: var(--text);
  font-size: 0.875rem;
}

.nav-menu a:hover {
  background: var(--primary-soft);
  color: var(--primary);
}

.page {
  max-width: 1100px;
  margin: 0 auto;
  padding: 28px 20px 64px;
}

.page-header {
  margin-bottom: 24px;
}

.page-header h1 {
  margin: 0 0 6px;
  font-size: 1.75rem;
  letter-spacing: -0.02em;
}

.page-header p {
  margin: 0;
  color: var(--text-secondary);
}

.hero {
  padding: 48px 0 32px;
  text-align: left;
}

.hero h1 {
  margin: 0 0 8px;
  font-size: clamp(2.2rem, 5vw, 3.2rem);
  letter-spacing: -0.04em;
  line-height: 1.1;
}

.hero .brand {
  color: var(--primary);
}

.hero p {
  margin: 0;
  max-width: 40rem;
  color: var(--text-secondary);
  font-size: 1.05rem;
}

.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 14px;
  margin-top: 28px;
}

.tool-card {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 18px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  color: inherit;
  transition: border-color 0.15s, transform 0.15s;
}

.tool-card:hover {
  border-color: var(--primary);
  transform: translateY(-1px);
  color: inherit;
}

.tool-card .icon {
  font-size: 1.4rem;
}

.tool-card h2 {
  margin: 0;
  font-size: 1.05rem;
}

.tool-card p {
  margin: 0;
  color: var(--text-secondary);
  font-size: 0.875rem;
}

.panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 16px;
}

.panel + .panel {
  margin-top: 14px;
}

.row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
}

.stack {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

@media (max-width: 800px) {
  .grid-2 {
    grid-template-columns: 1fr;
  }

  .nav-links .hide-sm {
    display: none;
  }
}

label {
  display: block;
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 6px;
}

input[type="text"],
input[type="number"],
input[type="datetime-local"],
select,
textarea {
  width: 100%;
  font: inherit;
  font-family: var(--mono);
  font-size: 0.9rem;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 12px;
  outline: none;
}

textarea {
  min-height: 180px;
  resize: vertical;
  line-height: 1.5;
}

input:focus,
select:focus,
textarea:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--primary) 25%, transparent);
}

.btn {
  appearance: none;
  border: 1px solid transparent;
  background: var(--primary);
  color: #fff;
  font: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  padding: 8px 14px;
  border-radius: 8px;
  cursor: pointer;
  white-space: nowrap;
}

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

.btn.secondary {
  background: var(--surface);
  color: var(--text);
  border-color: var(--border);
}

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

.btn.danger {
  background: var(--danger);
}

.muted {
  color: var(--text-secondary);
  font-size: 0.85rem;
}

.mono {
  font-family: var(--mono);
}

.ok {
  color: var(--success);
  background: var(--success-soft);
  border-radius: 8px;
  padding: 8px 12px;
  font-size: 0.9rem;
}

.err {
  color: var(--danger);
  background: var(--danger-soft);
  border-radius: 8px;
  padding: 8px 12px;
  font-size: 0.9rem;
}

.output {
  white-space: pre-wrap;
  word-break: break-word;
  font-family: var(--mono);
  font-size: 0.875rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px;
  min-height: 48px;
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--primary-soft);
  color: var(--primary);
  font-size: 0.8rem;
  font-weight: 600;
}

.site-footer {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 20px 40px;
  color: var(--text-secondary);
  font-size: 0.85rem;
}

.checkbox-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 18px;
}

.checkbox-row label {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin: 0;
  color: var(--text);
  cursor: pointer;
}

.checkbox-row input {
  width: auto;
}

.color-swatch {
  width: 100%;
  height: 120px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.diff-add {
  background: color-mix(in srgb, #10b981 18%, transparent);
}

.diff-del {
  background: color-mix(in srgb, #ef4444 18%, transparent);
}

.diff-same {
  opacity: 0.75;
}

.markdown-body {
  line-height: 1.7;
}

.markdown-body h1,
.markdown-body h2,
.markdown-body h3 {
  margin-top: 1.2em;
}

.markdown-body pre {
  background: var(--bg);
  padding: 12px;
  border-radius: 8px;
  overflow: auto;
}

.markdown-body code {
  font-family: var(--mono);
  font-size: 0.9em;
}

.qr-box {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 280px;
  background: #fff;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  padding: 16px;
}

.qr-box canvas,
.qr-box img {
  max-width: 100%;
}