:root {
      --bg: #f4f7fb;
      --bg-alt: #ffffff;
      --primary: #4f46e5;
      --primary-soft: #eef2ff;
      --accent: #22c55e;
      --text: #111827;
      --text-muted: #6b7280;
      --border: #e5e7eb;
      --radius-lg: 18px;
      --radius-md: 12px;
      --shadow-soft: 0 16px 32px rgba(148, 163, 184, 0.18);
      --shadow-card: 0 10px 22px rgba(148, 163, 184, 0.12);
    }

    html[data-theme="dark"] {
      --bg: #020617;
      --bg-alt: #020617;
      --primary: #6366f1;
      --primary-soft: rgba(79, 70, 229, 0.16);
      --accent: #22c55e;
      --text: #e5e7eb;
      --text-muted: #9ca3af;
      --border: #1f2933;
      --shadow-soft: 0 18px 35px rgba(0, 0, 0, 0.7);
      --shadow-card: 0 14px 30px rgba(0, 0, 0, 0.7);
    }

    * {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "SF Pro Text",
        "Segoe UI", sans-serif;
      color: var(--text);
      background:
        radial-gradient(circle at top left, #e0f2fe 0, transparent 40%),
        radial-gradient(circle at bottom right, #e0f2fe 0, transparent 45%),
        var(--bg);
    }

    html[data-theme="dark"] body {
      background:
        radial-gradient(circle at top left, rgba(56, 189, 248, 0.16) 0, transparent 40%),
        radial-gradient(circle at bottom right, rgba(129, 140, 248, 0.16) 0, transparent 45%),
        var(--bg);
    }

    a {
      color: inherit;
      text-decoration: none;
    }

    img {
      max-width: 100%;
      display: block;
    }

    .container {
      max-width: 1120px;
      margin: 0 auto;
      padding: 0 20px;
    }

    .site-header {
      position: sticky;
      top: 0;
      z-index: 20;
      backdrop-filter: blur(18px);
      background: rgba(244, 247, 251, 0.9);
      border-bottom: 1px solid rgba(209, 213, 219, 0.6);
    }

    html[data-theme="dark"] .site-header {
      background: rgba(15, 23, 42, 0.92);
      border-bottom: 1px solid rgba(30, 64, 175, 0.8);
    }

    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 12px 20px;
      gap: 16px;
      position: relative;
    }

    .logo {
      display: inline-flex;
      align-items: center;
      text-decoration: none;
      padding: 0;
      border: none;
      background: none;
    }

    .logo-img {
      height: 52px;
      width: auto;
      display: block;
      user-select: none;
    }

    .main-nav {
      display: flex;
      gap: 18px;
      font-size: 0.95rem;
      color: var(--text-muted);
      align-items: center;
    }

    .main-nav a {
      position: relative;
      padding: 4px 0;
    }

    .main-nav a::after {
      content: "";
      position: absolute;
      left: 0;
      bottom: -3px;
      width: 0;
      height: 2px;
      border-radius: 999px;
      background: linear-gradient(to right, var(--primary), var(--accent));
      transition: width 0.18s ease-out;
    }

    .main-nav a:hover::after {
      width: 100%;
    }

    .main-nav a.is-current::after {
      width: 100%;
    }

    .theme-switch {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      border: none;
      background: transparent;
      cursor: pointer;
      font-size: 0.8rem;
      color: var(--text-muted);
      padding: 0;
      border-radius: 999px;
      -webkit-tap-highlight-color: transparent;
    }

    .theme-switch:hover .theme-switch-track {
      box-shadow:
        0 6px 14px rgba(148, 163, 184, 0.55),
        0 0 0 1px rgba(148, 163, 184, 0.3);
    }

    .theme-switch:active .theme-switch-track {
      transform: scale(0.97);
    }

    .theme-switch:focus-visible .theme-switch-track {
      outline: 2px solid rgba(79, 70, 229, 0.7);
      outline-offset: 3px;
    }

    .theme-switch-track {
      width: 44px;
      height: 24px;
      border-radius: 999px;
      background: radial-gradient(circle at 30% 30%, #ffffff, rgba(148, 163, 184, 0.3));
      position: relative;
      display: inline-flex;
      align-items: center;
      padding: 3px;
      box-shadow:
        0 4px 10px rgba(148, 163, 184, 0.5),
        inset 0 0 0 1px rgba(148, 163, 184, 0.45);
      transition:
        background-color 0.22s cubic-bezier(0.22, 0.61, 0.36, 1),
        box-shadow 0.22s cubic-bezier(0.22, 0.61, 0.36, 1),
        transform 0.12s ease-out;
    }

    .theme-switch-thumb {
      width: 18px;
      height: 18px;
      border-radius: 999px;
      background: #ffffff;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      font-size: 0.7rem;
      color: #4b5563;
      transform: translateX(0);
      box-shadow:
        0 3px 6px rgba(15, 23, 42, 0.35),
        0 0 0 1px rgba(148, 163, 184, 0.6);
      transition:
        transform 0.22s cubic-bezier(0.22, 0.61, 0.36, 1),
        background-color 0.22s ease-out,
        color 0.22s ease-out,
        box-shadow 0.22s ease-out;
    }

    .theme-switch:active .theme-switch-thumb {
      box-shadow:
        0 1px 3px rgba(15, 23, 42, 0.45),
        0 0 0 1px rgba(148, 163, 184, 0.7);
    }

    .theme-switch.is-dark .theme-switch-track {
      background: radial-gradient(circle at 30% 30%, rgba(248, 250, 252, 0.25), #4f46e5);
      box-shadow:
        0 8px 18px rgba(79, 70, 229, 0.7),
        inset 0 0 0 1px rgba(191, 219, 254, 0.5);
    }

    .theme-switch.is-dark .theme-switch-thumb {
      transform: translateX(20px);
      background: #020617;
      color: #e5e7eb;
      box-shadow:
        0 4px 10px rgba(15, 23, 42, 0.85),
        0 0 0 1px rgba(55, 65, 81, 0.9);
    }

    html[data-theme="dark"] .theme-switch-track {
      background: radial-gradient(circle at 30% 30%, rgba(248, 250, 252, 0.12), rgba(15, 23, 42, 0.9));
      box-shadow:
        0 4px 10px rgba(15, 23, 42, 0.7),
        inset 0 0 0 1px rgba(30, 64, 175, 0.6);
    }

    main {
      padding: 32px 0 52px;
    }

    .hero {
      padding: 10px 0 26px;
    }

    .hero-inner {
      display: grid;
      grid-template-columns: minmax(0, 1.5fr) minmax(0, 1.1fr);
      gap: 26px;
      align-items: center;
    }

    .page-title {
      font-size: clamp(2.0rem, 3.2vw, 2.5rem);
      letter-spacing: -0.03em;
      margin: 0 0 10px;
    }

    .hero-intro {
      margin: 0 0 10px;
      color: var(--text-muted);
      max-width: 520px;
      line-height: 1.6;
      font-size: 1.02rem;
    }

    .hero-meta {
      font-size: 0.86rem;
      color: var(--text-muted);
      margin: 0;
    }

    .hero-panel {
      background: radial-gradient(circle at top left, #eef2ff, #ffffff);
      border-radius: var(--radius-lg);
      padding: 18px 18px 16px;
      box-shadow: var(--shadow-soft);
      border: 1px solid rgba(199, 210, 254, 0.8);
    }

    html[data-theme="dark"] .hero-panel {
      background: radial-gradient(circle at top left, rgba(15, 23, 42, 0.9), #020617);
      border-color: rgba(37, 99, 235, 0.8);
    }

    .hero-panel-header {
      margin-bottom: 8px;
    }

    .hero-panel-title {
      margin: 0;
      font-size: 0.98rem;
      font-weight: 600;
    }

    .hero-panel-tagline {
      margin: 2px 0 0;
      font-size: 0.8rem;
      color: var(--text-muted);
    }

    .tools-filter {
      margin-top: 8px;
    }

    .filter-row {
      display: flex;
      flex-wrap: wrap;
      gap: 8px;
      align-items: center;
    }

    .search-wrap {
      position: relative;
      flex: 1 1 320px;
      min-width: 0;
    }

    .search-input {
      width: 100%;
      padding: 8px 10px 8px 30px;
      border-radius: 999px;
      border: 1px solid var(--border);
      font-size: 0.9rem;
      outline: none;
      background: #ffffff;
      color: var(--text);
      box-shadow: 0 6px 14px rgba(148, 163, 184, 0.18);
    }

    .search-input::placeholder {
      color: #9ca3af;
    }

    .search-icon {
      position: absolute;
      left: 10px;
      top: 50%;
      transform: translateY(-50%);
      font-size: 0.85rem;
      color: #9ca3af;
    }

    .search-helper-text {
      margin-top: 6px;
      font-size: 0.78rem;
      color: var(--text-muted);
    }

    .search-helper-text span {
      font-weight: 500;
      color: #4f46e5;
    }

    html[data-theme="dark"] .search-input {
      background: #020617;
      border-color: #1f2937;
      box-shadow: 0 6px 16px rgba(0, 0, 0, 0.85);
      color: var(--text);
    }

    html[data-theme="dark"] .search-input::placeholder {
      color: #64748b;
    }

    html[data-theme="dark"] .search-icon {
      color: #64748b;
    }

    .search-dropdown {
      position: absolute;
      left: 0;
      top: calc(100% + 6px);
      width: 100%;
      max-height: 320px;
      overflow-y: auto;
      border-radius: 14px;
      border: 1px solid var(--border);
      background: #ffffff;
      box-shadow: 0 14px 32px rgba(148, 163, 184, 0.32);
      padding: 4px 0;
      display: none;
      z-index: 15;
    }

    .search-dropdown.visible {
      display: block;
    }

    html[data-theme="dark"] .search-dropdown {
      background: #020617;
      border-color: #1f2937;
      box-shadow: 0 18px 40px rgba(0, 0, 0, 0.9);
    }

    .search-item {
      padding: 7px 12px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 10px;
      font-size: 0.9rem;
      cursor: pointer;
    }

    .search-item-main {
      display: flex;
      flex-direction: column;
      gap: 2px;
      min-width: 0;
    }

    .search-item-title {
      font-weight: 500;
      color: var(--text);
      white-space: nowrap;
      overflow: hidden;
      text-overflow: ellipsis;
    }

    .search-item-subtitle {
      font-size: 0.8rem;
      color: var(--text-muted);
      white-space: nowrap;
      overflow: hidden;
      text-overflow: ellipsis;
    }

    .search-item-meta {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      font-size: 0.78rem;
      color: var(--text-muted);
      white-space: nowrap;
      flex-shrink: 0;
    }

    .search-item-meta-badge {
      padding: 2px 7px;
      border-radius: 999px;
      border: 1px solid #e5e7eb;
      background: #f9fafb;
      font-size: 0.75rem;
    }

    html[data-theme="dark"] .search-item-meta-badge {
      border-color: #1f2937;
      background: #020617;
    }

    .search-item:hover {
      background: #f3f4ff;
    }

    html[data-theme="dark"] .search-item:hover {
      background: rgba(30, 64, 175, 0.3);
    }

    .about-article-wrapper {
      max-width: 820px;
      margin: 6px auto 0;
    }

    .about-article {
      background: #ffffff;
      border-radius: var(--radius-lg);
      border: 1px solid var(--border);
      box-shadow: var(--shadow-card);
      padding: 24px 22px 22px;
    }

    @media (min-width: 720px) {
      .about-article {
        padding: 28px 32px 26px;
      }
    }

    html[data-theme="dark"] .about-article {
      background: rgba(15, 23, 42, 0.96);
      border-color: #1f2937;
      box-shadow: 0 18px 38px rgba(0, 0, 0, 0.9);
    }

    .about-article-section {
      margin-bottom: 18px;
    }

    .about-article-section:last-of-type {
      margin-bottom: 0;
    }

    .about-article h2 {
      font-size: 1.18rem;
      margin: 0 0 8px;
      letter-spacing: -0.01em;
    }

    .about-article p {
      margin: 0 0 10px;
      color: var(--text-muted);
      line-height: 1.7;
      font-size: 1.02rem;
    }

    .about-article p:last-child {
      margin-bottom: 0;
    }

    .about-lead {
      font-size: 1.04rem;
      color: var(--text);
      margin-bottom: 16px;
    }

    .about-divider {
      height: 1px;
      border: 0;
      background: linear-gradient(to right, rgba(209, 213, 219, 0.9), transparent);
      margin: 6px 0 18px;
    }

    .about-callout {
      margin-top: 4px;
      padding: 10px 12px;
      border-radius: 12px;
      background: #f9fafb;
      border: 1px dashed rgba(148, 163, 184, 0.7);
      font-size: 0.9rem;
      color: var(--text-muted);
    }

    .about-callout i {
      margin-right: 6px;
      color: #4f46e5;
    }

    html[data-theme="dark"] .about-callout {
      background: rgba(15, 23, 42, 0.9);
      border-color: rgba(51, 65, 85, 0.9);
      color: var(--text-muted);
    }

    html[data-theme="dark"] .about-callout i {
      color: #6366f1;
    }

    .about-article ul {
      margin: 0 0 10px 1.2rem;
      padding: 0;
      color: var(--text-muted);
      line-height: 1.7;
      font-size: 1.02rem;
    }

    .about-article li + li {
      margin-top: 4px;
    }

    .about-article strong {
      font-weight: 600;
      color: var(--text);
    }

    .email-button-wrap {
      margin-top: 10px;
      margin-bottom: 4px;
    }

    .email-button {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      padding: 9px 16px;
      border-radius: 999px;
      border: 1px solid rgba(148, 163, 184, 0.9);
      background: linear-gradient(135deg, #ffffff, #f9fafb);
      font-size: 0.92rem;
      font-weight: 500;
      color: var(--text);
      cursor: pointer;
      box-shadow: 0 8px 18px rgba(148, 163, 184, 0.18);
    }

    .email-button i {
      font-size: 0.95rem;
      color: #4f46e5;
    }

    .email-button:hover {
      background: #ffffff;
      border-color: rgba(79, 70, 229, 0.95);
      box-shadow: 0 14px 28px rgba(148, 163, 184, 0.26);
    }

    html[data-theme="dark"] .email-button {
      background: radial-gradient(circle at top left, rgba(15, 23, 42, 0.95), #020617);
      border-color: #1f2937;
      color: var(--text);
      box-shadow: 0 16px 32px rgba(0, 0, 0, 0.9);
    }

    html[data-theme="dark"] .email-button i {
      color: #6366f1;
    }

    .email-helper {
      font-size: 0.85rem;
      color: var(--text-muted);
      margin: 4px 0 0;
    }

    .site-footer {
      border-top: 1px solid rgba(209, 213, 219, 0.7);
      padding: 20px 0 26px;
      background: rgba(248, 250, 252, 0.96);
    }

    html[data-theme="dark"] .site-footer {
      background: rgba(15, 23, 42, 0.98);
      border-top: 1px solid rgba(30, 64, 175, 0.8);
    }

    .footer-inner {
      display: flex;
      flex-wrap: wrap;
      align-items: center;
      justify-content: space-between;
      gap: 10px;
      font-size: 0.86rem;
      color: var(--text-muted);
    }

    .footer-brand {
      display: flex;
      flex-direction: column;
      gap: 2px;
    }

    .footer-brand .logo-wordmark {
      font-size: 1rem;
    }

    .footer-note {
      font-size: 0.8rem;
    }

    .footer-nav {
      display: flex;
      gap: 12px;
      flex-wrap: wrap;
    }

    .footer-nav a {
      padding: 2px 0;
    }

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

    .footer-meta {
      margin: 0;
      width: 100%;
      text-align: right;
      font-size: 0.78rem;
    }

    .footer-language {
      position: relative;
      display: flex;
      align-items: center;
      justify-content: flex-end;
      gap: 8px;
      min-width: 0;
    }

    .lang-toggle {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      padding: 6px 12px;
      border-radius: 999px;
      border: 1px solid rgba(148, 163, 184, 0.9);
      background: rgba(255, 255, 255, 0.96);
      font-size: 0.82rem;
      color: var(--text-muted);
      cursor: pointer;
      outline: none;
      white-space: nowrap;
    }

    .lang-toggle i.fa-globe {
      font-size: 0.85rem;
    }

    .lang-toggle .lang-chevron {
      font-size: 0.75rem;
      transition: transform 0.14s ease-out;
    }

    .lang-toggle.is-open .lang-chevron {
      transform: rotate(180deg);
    }

    .lang-toggle:hover {
      border-color: rgba(79, 70, 229, 0.95);
      color: var(--primary);
      background: #ffffff;
      box-shadow: 0 8px 18px rgba(148, 163, 184, 0.22);
    }

    html[data-theme="dark"] .lang-toggle {
      background: #020617;
      border-color: #1f2937;
      box-shadow: 0 8px 18px rgba(0, 0, 0, 0.85);
      color: var(--text-muted);
    }

    html[data-theme="dark"] .lang-toggle i.fa-globe {
      color: #6366f1;
    }

    .lang-dropdown {
      position: absolute;
      right: 0;
      bottom: calc(100% + 6px);
      min-width: 100px;
      max-height: 260px;
      overflow-y: auto;
      padding: 6px 0;
      border-radius: 14px;
      border: 1px solid var(--border);
      background: #ffffff;
      box-shadow: 0 16px 30px rgba(148, 163, 184, 0.3);
      display: none;
      z-index: 30;
    }

    .lang-dropdown.is-open {
      display: block;
    }

    html[data-theme="dark"] .lang-dropdown {
      background: #020617;
      border-color: #1f2937;
      box-shadow: 0 20px 40px rgba(0, 0, 0, 0.92);
    }

    .lang-option {
      display: flex;
      align-items: center;
      padding: 6px 12px;
      font-size: 0.82rem;
      color: var(--text-muted);
      text-decoration: none;
      white-space: nowrap;
    }

    .lang-option:hover {
      background: #f3f4ff;
      color: var(--primary);
    }

    .lang-option.is-active {
      font-weight: 600;
      color: var(--primary);
      background: #eef2ff;
    }

    html[data-theme="dark"] .lang-option:hover {
      background: rgba(30, 64, 175, 0.35);
      color: #e5e7eb;
    }

    html[data-theme="dark"] .lang-option.is-active {
      background: rgba(37, 99, 235, 0.4);
      color: #e5e7eb;
    }

    @media (max-width: 800px) {
      .header-inner {
        flex-wrap: wrap;
        justify-content: space-between;
        padding: 12px 20px 8px;
      }

      .main-nav {
        width: 100%;
        justify-content: flex-start;
        flex-wrap: wrap;
        border-top: 1px solid rgba(209, 213, 219, 0.7);
        padding-top: 8px;
        margin-top: 4px;
      }

      html[data-theme="dark"] .main-nav {
        border-top: 1px solid rgba(31, 41, 55, 0.9);
      }

      .theme-switch {
        position: absolute;
        right: 20px;
        top: 22px;
        transform: none;
      }

      .hero-inner {
        grid-template-columns: minmax(0, 1fr);
      }

      .hero-panel {
        order: -1;
      }
    }

    @media (max-width: 520px) {
      .footer-inner {
        align-items: flex-start;
      }

      .footer-language {
        width: 100%;
        justify-content: flex-start;
      }

      .lang-dropdown {
        right: auto;
        left: 0;
        max-width: 100%;
      }

      .footer-meta {
        text-align: left;
      }
    }