:root {
  --bg: #ffffff;
  --text: #121212;
  --muted: #666666;
  --border: #e8e8e8;
  --card: #f8f8f8;
  --accent: #111111;
  --success: #0a7a33;
  --max: 1120px;
  --radius: 16px;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.03);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
}

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

button {
  font: inherit;
}

.container {
  width: min(100% - 32px, var(--max));
  margin: 0 auto;
}

.site-header {
  border-bottom: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 20;
}

.site-header .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 18px 0;
}

.logo {
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.nav {
  display: flex;
  gap: 22px;
  flex-wrap: wrap;
}

.nav a {
  color: var(--muted);
  font-size: 0.98rem;
}

.hero {
  padding: 72px 0 42px;
}

.hero-inner {
  text-align: center;
}

.hero h1 {
  font-size: clamp(2.2rem, 6vw, 4.2rem);
  line-height: 1.06;
  margin: 0 0 16px;
  letter-spacing: -0.04em;
}

.hero-text,
.subtitle {
  max-width: 760px;
  margin: 0 auto 26px;
  color: var(--muted);
  font-size: 1.08rem;
}

.helper-text {
  margin: 0;
  color: var(--muted);
  font-size: 0.96rem;
}

.search-wrap {
  max-width: 760px;
  margin: 0 auto;
}

.search-box {
  max-width: 760px;
  margin: 0 auto;
}

.search-box input {
  width: 100%;
  padding: 18px 22px;
  border: 1px solid var(--border);
  border-radius: 999px;
  font-size: 1rem;
  outline: none;
  background: #fff;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.search-box input:focus {
  border-color: #bfbfbf;
  box-shadow: 0 0 0 4px rgba(0, 0, 0, 0.035);
}

.search-empty {
  color: var(--muted);
  font-size: 0.95rem;
  text-align: center;
  margin-top: 18px;
  display: none;
}

.symbol-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 16px;
  margin-top: 28px;
}

.symbol-tile,
.copy-btn,
.copy-chip,
.shortcut-chip {
  cursor: pointer;
}

.symbol-tile {
  border: 1px solid var(--border);
  background: #fff;
  border-radius: var(--radius);
  padding: 22px 12px 18px;
  font-size: 2.2rem;
  font-weight: 700;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
  transition: transform 0.15s ease, border-color 0.15s ease, box-shadow 0.15s ease;
  box-shadow: 0 0 0 rgba(0, 0, 0, 0);
  min-height: 140px;
  appearance: none;
  -webkit-appearance: none;
  text-align: center;
}

.symbol-tile:hover,
.symbol-tile:focus-visible {
  transform: translateY(-2px);
  border-color: #cfcfcf;
  box-shadow: var(--shadow);
}

.symbol-tile span {
  font-size: 1rem;
  font-weight: 500;
  color: var(--muted);
}

.section {
  padding: 54px 0;
}

.section.alt {
  background: #fafafa;
  border-top: 1px solid #f1f1f1;
  border-bottom: 1px solid #f1f1f1;
}

.section h2,
article h2 {
  font-size: 1.85rem;
  margin: 0 0 18px;
  letter-spacing: -0.03em;
}

.section-intro {
  color: var(--muted);
  margin-top: -6px;
  margin-bottom: 22px;
}

.link-grid,
.related-links {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 14px;
}

.link-grid a,
.related-links a {
  display: block;
  padding: 16px 18px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: #fff;
  transition: border-color 0.15s ease, transform 0.15s ease;
}

.link-grid a:hover,
.related-links a:hover {
  border-color: #cfcfcf;
  transform: translateY(-1px);
}

.article-page {
  padding: 32px 0 64px;
}

.breadcrumb {
  font-size: 0.95rem;
  color: var(--muted);
  margin-bottom: 18px;
}

.breadcrumb a {
  color: var(--muted);
}

.breadcrumb span {
  margin: 0 4px;
}

.page-header {
  margin-bottom: 20px;
}

.page-header h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  line-height: 1.08;
  margin: 0 0 14px;
  letter-spacing: -0.04em;
}

.quick-answer,
.section-card,
.info-box,
.table-wrap {
  border: 1px solid var(--border);
  border-radius: 18px;
  background: #fff;
  padding: 22px;
  margin: 22px 0;
}

.hero-symbol-box {
  margin: 28px 0;
}

.symbol-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 22px;
  padding: 36px 28px;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 18px;
  min-height: 230px;
}

.symbol-char {
  font-size: 4rem;
  line-height: 1;
  margin: 0;
}

.copy-actions {
  display: flex;
  gap: 12px;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  margin: 0;
}

.copy-btn,
.copy-chip {
  border: none;
  background: var(--accent);
  color: #fff;
  padding: 12px 18px;
  border-radius: 999px;
  font-size: 0.95rem;
  transition: transform 0.12s ease, opacity 0.12s ease, background 0.12s ease;
}

.copy-btn:hover,
.copy-chip:hover {
  transform: translateY(-1px);
}

.copy-btn.copied,
.copy-chip.copied {
  background: var(--success);
}

.shortcut-list {
  margin: 0;
  padding-left: 20px;
}

.shortcut-list li {
  margin: 8px 0;
}

.shortcut-chip {
  display: inline-flex;
  align-items: center;
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 10px 14px;
  background: #fff;
  margin: 6px 8px 0 0;
}

.inline-symbol {
  font-size: 2.2rem;
  line-height: 1;
  padding: 12px 16px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: #fff;
  min-width: 72px;
  text-align: center;
}

.copy-inline {
  display: flex;
  gap: 12px;
  align-items: center;
  flex-wrap: wrap;
}

.related-symbols-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(110px, 1fr));
  gap: 12px;
  margin-top: 14px;
}

.related-symbol-tile {
  display: block;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: #fff;
  padding: 16px 8px;
  text-align: center;
  transition: border-color 0.15s ease, transform 0.15s ease;
}

.related-symbol-tile:hover {
  border-color: #cfcfcf;
  transform: translateY(-1px);
}

.related-symbol-tile .sym {
  display: block;
  font-size: 1.8rem;
  margin-bottom: 6px;
}

.related-symbol-tile .name {
  color: var(--muted);
  font-size: 0.92rem;
}

.info-table {
  width: 100%;
  border-collapse: collapse;
}

.info-table th,
.info-table td {
  border-top: 1px solid var(--border);
  padding: 12px 10px;
  text-align: left;
  vertical-align: top;
}

.info-table thead th {
  border-top: none;
}

.faq-item {
  border-top: 1px solid var(--border);
  padding: 18px 0;
}

.faq-item:first-of-type {
  border-top: none;
  padding-top: 0;
}

.site-footer {
  border-top: 1px solid var(--border);
  padding: 28px 0;
  color: var(--muted);
  margin-top: 48px;
  font-size: 0.96rem;
}

.utility-row {
  display: flex;
  gap: 12px;
  align-items: center;
  flex-wrap: wrap;
}

@media (max-width: 780px) {
  .site-header .container {
    flex-direction: column;
    gap: 12px;
  }

  .nav {
    justify-content: center;
  }

  .hero {
    padding-top: 56px;
  }

  .symbol-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-header h1 {
    font-size: 2.6rem;
  }

  .symbol-card {
    min-height: 210px;
    padding: 30px 20px;
  }
}

@media (max-width: 520px) {
  .search-box input {
    padding: 16px 18px;
  }

  .symbol-char {
    font-size: 3.6rem;
  }

  .copy-actions {
    flex-direction: column;
    width: 100%;
  }

  .copy-btn,
  .copy-chip {
    width: 100%;
    max-width: 260px;
  }

  .page-header h1 {
    font-size: 2.2rem;
  }
}