:root {
  --color-bg: #f7f8fa;
  --color-surface: #ffffff;
  --color-text: #1c1f26;
  --color-text-muted: #5b6472;
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-border: #e2e5ea;
  --color-accent-bg: #eef2ff;
  --radius: 10px;
  --max-width: 960px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Kaku Gothic ProN", "Yu Gothic", sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #14161a;
    --color-surface: #1d2026;
    --color-text: #e8eaed;
    --color-text-muted: #a1a8b3;
    --color-primary: #5b8def;
    --color-primary-dark: #7ba1f2;
    --color-border: #2c3038;
    --color-accent-bg: #1e2433;
  }
}

* {
  box-sizing: border-box;
}

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

body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
}

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

.site-header {
  border-bottom: 1px solid var(--color-border);
  background: var(--color-surface);
}

.site-header__inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 14px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}

.site-header__logo {
  font-weight: 700;
  font-size: 1.05rem;
  text-decoration: none;
  color: var(--color-text);
}

.site-header__nav {
  display: flex;
  gap: 18px;
  flex-wrap: wrap;
}

.site-header__nav a {
  text-decoration: none;
  color: var(--color-text-muted);
  font-size: 0.92rem;
}

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

main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 32px 20px 60px;
}

.breadcrumb {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-bottom: 18px;
}

.breadcrumb a {
  color: var(--color-text-muted);
  text-decoration: none;
}

.breadcrumb a:hover {
  text-decoration: underline;
}

h1 {
  font-size: 1.6rem;
  margin: 0 0 10px;
}

h2 {
  font-size: 1.2rem;
  margin: 32px 0 12px;
}

.lead {
  color: var(--color-text-muted);
  margin: 0 0 28px;
}

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
}

.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 14px;
  margin: 20px 0 40px;
}

.tool-card {
  display: block;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 18px;
  text-decoration: none;
  color: var(--color-text);
  transition: border-color 0.15s ease, transform 0.15s ease;
}

.tool-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-2px);
}

.tool-card__title {
  font-weight: 600;
  margin-bottom: 6px;
}

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

.tool-card__category {
  display: inline-block;
  font-size: 0.72rem;
  color: var(--color-primary);
  background: var(--color-accent-bg);
  border-radius: 999px;
  padding: 2px 10px;
  margin-bottom: 10px;
}

.field {
  margin-bottom: 18px;
}

.field label {
  display: block;
  font-size: 0.88rem;
  font-weight: 600;
  margin-bottom: 6px;
}

.field input[type="text"],
.field input[type="number"],
.field input[type="date"],
.field select,
.field textarea {
  width: 100%;
  padding: 10px 12px;
  font-size: 1rem;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: inherit;
}

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

.checkbox-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 8px;
}

.checkbox-row label {
  font-size: 0.9rem;
  font-weight: 400;
}

.btn {
  display: inline-block;
  background: var(--color-primary);
  color: #fff;
  border: none;
  padding: 11px 22px;
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
}

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

.result-box {
  margin-top: 22px;
  padding: 18px 20px;
  background: var(--color-accent-bg);
  border-radius: var(--radius);
  font-size: 1.05rem;
  min-height: 24px;
}

.result-box.is-empty {
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

.result-box .big {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.error-text {
  color: #dc2626;
  font-size: 0.88rem;
  margin-top: 8px;
}

.note-box {
  margin-top: 28px;
  font-size: 0.85rem;
  color: var(--color-text-muted);
  border-top: 1px solid var(--color-border);
  padding-top: 16px;
}

.ad-slot {
  margin: 28px 0;
  padding: 10px;
  text-align: center;
  font-size: 0.72rem;
  color: var(--color-text-muted);
  border: 1px dashed var(--color-border);
  border-radius: 8px;
}

.site-footer {
  border-top: 1px solid var(--color-border);
  margin-top: 40px;
}

.site-footer__inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 24px 20px 40px;
  font-size: 0.82rem;
  color: var(--color-text-muted);
  display: flex;
  gap: 18px;
  flex-wrap: wrap;
  justify-content: space-between;
}

.site-footer__links {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
}

.site-footer__links a {
  color: var(--color-text-muted);
  text-decoration: none;
}

.site-footer__links a:hover {
  text-decoration: underline;
}

table.simple-table {
  border-collapse: collapse;
  width: 100%;
  font-size: 0.9rem;
}

table.simple-table th,
table.simple-table td {
  border: 1px solid var(--color-border);
  padding: 8px 10px;
  text-align: left;
}

canvas#qr-canvas {
  background: #fff;
  border-radius: 8px;
  padding: 12px;
}

@media (max-width: 768px) {
  main {
    padding: 24px 16px 48px;
  }
  .site-header__inner {
    padding: 12px 16px;
  }
}