html {
      scroll-behavior: smooth;
    }

    body {
      margin: 0;
      background: #f6f7f8;
      color: #2f2f2f;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
      line-height: 1.7;
    }

    * {
      box-sizing: border-box;
    }

    .help-support {
      max-width: 1100px;
      margin: 0 auto;
      padding: 20px 14px 44px;
      font-size: 16px;
    }

    .help-header {
      margin: 0 0 22px;
      padding: 20px 18px;
      border: 1px solid #ddd;
      border-radius: 14px;
      background: #fff;
      box-shadow: 0 4px 18px rgba(0, 0, 0, 0.04);
    }

    .top-anchor {
      position: relative;
      top: -4px;
    }

    .help-support h1 {
      margin: 0 0 8px;
      font-size: clamp(28px, 4vw, 38px);
      line-height: 1.18;
    }

    .help-subtitle {
      margin: 0 0 16px;
      color: #666;
      font-size: 17px;
    }

    .help-intro {
      margin: 0;
      color: #555;
      max-width: 850px;
      font-size: 16px;
      line-height: 1.7;
    }

    .help-search {
      margin: 22px 0 20px;
    }

    .help-search-input {
      width: 100%;
      padding: 13px 16px;
      border: 1px solid #cfcfcf;
      border-radius: 10px;
      background: #fff;
      font: inherit;
      font-size: 16px;
      outline: none;
    }

    .help-search-input:focus {
      border-color: #888;
      box-shadow: 0 0 0 3px rgba(0, 0, 0, 0.06);
    }

    .help-search-info {
      margin: 8px 2px 0;
      color: #777;
      font-size: 15px;
    }

    .help-categories {
      display: grid;
      grid-template-columns: 1fr;
      gap: 12px;
      margin: 0 0 28px;
    }

    .help-category-card {
      display: flex;
      align-items: flex-start;
      gap: 14px;
      padding: 16px 16px;
      border: 1px solid #ddd;
      border-radius: 12px;
      background: #fff;
      color: #222;
      text-decoration: none;
      box-shadow: 0 4px 16px rgba(0, 0, 0, 0.03);
      transition:
        border-color 0.2s ease,
        box-shadow 0.2s ease,
        transform 0.2s ease;
    }

    .help-category-card:hover {
      border-color: #bbb;
      box-shadow: 0 6px 18px rgba(0, 0, 0, 0.07);
      transform: translateY(-1px);
      color: #222;
      text-decoration: none;
    }

    .help-category-card:focus-visible,
    .section-top-link:focus-visible,
    .back-to-top:focus-visible {
      outline: 2px solid #111;
      outline-offset: 2px;
    }

    .icon-badge {
      flex: 0 0 auto;
      width: 46px;
      height: 46px;
      border-radius: 10px;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      background: #f1f3f5;
      border: 1px solid #dfe3e6;
      line-height: 1;
    }

    .icon-badge img {
      width: 30px;
      height: 30px;
      display: block;
    }

    .help-category-content {
      min-width: 0;
    }

    .help-category-title {
      display: block;
      margin-bottom: 4px;
      font-weight: 700;
      font-size: 17px;
      line-height: 1.35;
    }

    .help-category-meta {
      color: #777;
      font-size: 15px;
      line-height: 1.45;
    }



    .support-links {
      display: grid;
      grid-template-columns: 1fr;
      gap: 10px;
      margin-top: 14px;
    }

    .support-link {
      display: block;
      padding: 13px 15px;
      border: 1px solid #ddd;
      border-radius: 8px;
      background: #fff;
      color: #222;
      text-decoration: none;
      font-size: 16px;
      font-weight: 600;
    }

    .support-link:hover {
      border-color: #bbb;
      background: #fafafa;
      color: #222;
      text-decoration: none;
    }

    .safety-note {
      margin-top: 18px;
      padding: 15px 16px;
      border-left: 4px solid #b3261e;
      border-radius: 6px;
      background: #fff4f3;
      color: #333;
      font-size: 16px;
      line-height: 1.6;
    }

    .safety-note strong {
      display: block;
      margin-bottom: 4px;
    }

    .knowhow-grid {
      display: grid;
      grid-template-columns: 1fr;
      gap: 12px;
      margin: 12px 0 0;
    }

    .knowhow-card {
      display: block;
      padding: 16px 18px;
      border: 1px solid #ddd;
      border-radius: 10px;
      background: #fff;
      color: #222;
      text-decoration: none;
      transition:
        border-color 0.2s ease,
        box-shadow 0.2s ease,
        transform 0.2s ease;
    }

    .knowhow-card:hover {
      border-color: #bbb;
      box-shadow: 0 4px 14px rgba(0, 0, 0, 0.07);
      transform: translateY(-1px);
      color: #222;
      text-decoration: none;
    }

    .knowhow-card-title {
      display: block;
      margin-bottom: 4px;
      font-size: 17px;
      line-height: 1.35;
      font-weight: 700;
    }

    .knowhow-card-text {
      display: block;
      color: #666;
      font-size: 16px;
      line-height: 1.55;
    }

    .knowhow-card-link {
      display: block;
      margin-top: 9px;
      color: #007bff;
      font-size: 15px;
      font-weight: 600;
    }

    .faq-empty {
      display: none;
      margin: 16px 0 20px;
      padding: 16px 18px;
      border: 1px solid #ddd;
      border-radius: 10px;
      background: #fff;
      color: #666;
    }

    .faq-section {
      margin: 0 0 28px;
      scroll-margin-top: 16px;
    }

    .faq-section-card {
      padding: 18px 0 0;
    }

    .faq-section-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 12px;
      margin: 0 0 10px;
      flex-wrap: wrap;
    }

    .faq-section-title-wrap {
      display: flex;
      align-items: center;
      gap: 12px;
      min-width: 0;
    }

    .faq-section-title {
      margin: 0;
      font-size: clamp(20px, 2vw, 22px);
      line-height: 1.3;
    }

    .faq-section-description {
      margin: -2px 0 12px 0;
      color: #777;
      font-size: 15px;
    }

    .section-top-link {
      flex: 0 0 auto;
      color: #007bff;
      text-decoration: none;
      font-weight: 600;
      font-size: 15px;
      white-space: nowrap;
    }

    .section-top-link:hover {
      text-decoration: underline;
    }

    .faq-list {
      overflow: hidden;
      border-radius: 12px;
      border: 1px solid #ddd;
      background: #fff;
      box-shadow: 0 4px 16px rgba(0, 0, 0, 0.03);
    }

    .faq-item {
      border-bottom: 1px solid #eee;
      padding: 0 16px;
      font-size: 16px;
    }

    .faq-item:last-of-type {
      border-bottom: none;
    }

    .faq-question {
      cursor: pointer;
      list-style: none;
      padding: 17px 0;
      font-weight: 700;
      display: flex;
      align-items: center;
      gap: 14px;
      font-size: 17px;
      line-height: 1.45;
    }

    .faq-question::-webkit-details-marker {
      display: none;
    }

    .faq-question::after {
      content: "+";
      margin-left: auto;
      flex: 0 0 auto;
      width: 28px;
      height: 28px;
      border-radius: 50%;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      font-weight: 600;
      font-size: 20px;
      line-height: 1;
      color: #666;
      background: #f2f2f2;
      border: 1px solid #e2e2e2;
    }

    details[open] .faq-question::after {
      content: "–";
    }

    .faq-question:hover {
      color: #111;
    }

    .faq-answer {
      color: #3c3c3c;
      font-size: 16px;
      line-height: 1.7;
      max-height: 0;
      overflow: hidden;
      opacity: 0;
      padding: 0;
      transition:
        max-height 0.35s ease,
        opacity 0.25s ease,
        padding-top 0.25s ease,
        padding-bottom 0.25s ease;
    }

    details[open] .faq-answer {
      max-height: 2200px;
      opacity: 1;
      padding-top: 4px;
      padding-bottom: 18px;
    }

    .faq-answer p:first-child {
      margin-top: 0;
    }

    .faq-answer ul {
      padding-left: 22px;
      margin: 8px 0 0;
    }

    .faq-answer li {
      margin-bottom: 8px;
    }

    .faq-link-row {
      text-align: left;
      margin: 16px 0 2px;
    }

    .faq-link-row .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      max-width: 100%;
    }

    .faq-note {
      margin: 14px 0 4px;
      padding: 12px 14px;
      border-left: 4px solid #c8a200;
      background: #fff8d8;
      border-radius: 6px;
    }

    .faq-note strong {
      display: block;
      margin-bottom: 2px;
    }

    .faq-note.info {
      border-left-color: #7a8b99;
      background: #f3f6f8;
    }

    .btn {
      padding: 10px 16px;
      border-radius: 6px;
      border: 1px solid #007bff;
      text-decoration: none;
      font-weight: 600;
      font-size: 15px;
    }

    .btn-primary {
      background-color: #007bff;
      color: #fff;
    }

    .btn-primary:hover {
      background-color: #0056b3;
      color: #fff;
      text-decoration: none;
    }

    .is-hidden {
      display: none !important;
    }

    .back-to-top {
      position: fixed;
      right: 16px;
      bottom: 16px;
      z-index: 1000;
      display: inline-flex;
      align-items: center;
      gap: 8px;
      padding: 11px 14px;
      border-radius: 999px;
      background: #111;
      color: #fff;
      text-decoration: none;
      font-weight: 700;
      box-shadow: 0 8px 22px rgba(0, 0, 0, 0.18);
      opacity: 0;
      visibility: hidden;
      transform: translateY(10px);
      transition:
        opacity 0.25s ease,
        visibility 0.25s ease,
        transform 0.25s ease;
    }

    .back-to-top.is-visible {
      opacity: 1;
      visibility: visible;
      transform: translateY(0);
    }

    .back-to-top img {
      width: 18px;
      height: 18px;
      display: block;
      filter: brightness(0) invert(1);
    }

    .back-to-top:hover {
      color: #fff;
      text-decoration: none;
      background: #000;
    }

    .sr-only {
      position: absolute;
      width: 1px;
      height: 1px;
      padding: 0;
      margin: -1px;
      overflow: hidden;
      clip: rect(0, 0, 0, 0);
      white-space: nowrap;
      border: 0;
    }

    @media (max-width: 639px) {
      .help-support {
        padding: 14px 10px 80px;
      }

      .help-header {
        padding: 18px 14px;
        border-radius: 12px;
      }

      .faq-item {
        padding: 0 14px;
      }

      .faq-question {
        padding: 15px 0;
        font-size: 16px;
      }

      .faq-link-row .btn {
        width: 100%;
      }

      .section-top-link {
        width: 100%;
      }

      .back-to-top {
        right: 12px;
        bottom: 12px;
        padding: 10px 13px;
      }
    }

    @media (min-width: 700px) {
      .knowhow-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
      }

      .support-links {
        grid-template-columns: repeat(3, minmax(0, 1fr));
      }

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

      .faq-item {
        padding: 0 20px;
      }
    }

    @media (min-width: 1024px) {
      .help-support {
        padding-top: 28px;
        padding-bottom: 54px;
      }
    }

    @media (pointer: coarse) {
      .faq-question,
      .section-top-link,
      .help-category-card,
      .back-to-top,
      .btn {
        min-height: 44px;
      }
    }

    @media (prefers-reduced-motion: reduce) {
      html {
        scroll-behavior: auto;
      }

      .help-category-card,
      .faq-answer,
      .back-to-top {
        transition: none;
      }
    }