/* ==========================================================================
       Design System & Variables
       Base Canvas Color: #f1f4ff (Strict Requirement)
       Audience: Young Global Stationery Enthusiasts & Aesthetic Desk Curators
       Strict Guardrails: ZERO links (<a>), ZERO buttons (<button>), ZERO brand/company names
       ========================================================================== */
    :root {
      --bg-canvas: #f1f4ff;
      --bg-surface: #ffffff;
      --bg-surface-soft: #f8faff;
      --text-main: #0f172a;
      --text-body: #334155;
      --text-muted: #64748b;
      --accent-pop: #3b82f6;
      --accent-yellow: #f59e0b;
      --accent-pink: #ec4899;
      --border-color: #dbe4ff;
      --border-card: #e2e8f0;
      --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
      --shadow-sm: 0 2px 8px rgba(15, 23, 42, 0.04);
      --shadow-md: 0 10px 25px rgba(30, 41, 59, 0.06);
      --shadow-hover: 0 16px 36px rgba(30, 41, 59, 0.1);
      --radius-xl: 20px;
      --radius-lg: 16px;
      --radius-md: 10px;
      --radius-pill: 9999px;
    }

    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      background-color: var(--bg-canvas);
      color: var(--text-body);
      font-family: var(--font-family);
      line-height: 1.6;
      font-size: 15px;
      padding: 0;
      margin: 0;
      -webkit-font-smoothing: antialiased;
    }

    .container {
      max-width: 1120px;
      margin: 0 auto;
      padding: 40px 20px 80px;
    }

    /* ==========================================================================
       Header / Hero Showcase Section
       ========================================================================== */
    .hero-section {
      text-align: center;
      margin-bottom: 40px;
      padding: 44px 28px;
      background: var(--bg-surface);
      border-radius: var(--radius-xl);
      border: 1px solid var(--border-color);
      box-shadow: var(--shadow-sm);
    }

    .hero-badge {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      padding: 6px 16px;
      background-color: #e0e7ff;
      color: #3730a3;
      font-size: 13px;
      font-weight: 700;
      border-radius: var(--radius-pill);
      letter-spacing: 0.5px;
      text-transform: uppercase;
      margin-bottom: 16px;
    }

    .hero-title {
      font-size: 32px;
      font-weight: 800;
      color: var(--text-main);
      letter-spacing: -0.5px;
      margin-bottom: 16px;
      line-height: 1.25;
    }

    .hero-desc {
      font-size: 16px;
      color: var(--text-body);
      max-width: 800px;
      margin: 0 auto 24px;
      line-height: 1.65;
    }

    .feature-tags {
      display: flex;
      flex-wrap: wrap;
      justify-content: center;
      gap: 12px;
      margin-top: 20px;
    }

    .feature-tag-item {
      display: inline-flex;
      align-items: center;
      padding: 8px 16px;
      background: var(--bg-surface-soft);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-pill);
      font-size: 13px;
      font-weight: 600;
      color: var(--text-main);
      box-shadow: var(--shadow-sm);
    }

    /* ==========================================================================
       16-Image Product Gallery Grid (Strict 2 Columns Desktop, 1 Column Mobile)
       ========================================================================== */
    .gallery-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 28px;
      margin-bottom: 50px;
    }

    .gallery-card {
      background: var(--bg-surface);
      border-radius: var(--radius-lg);
      border: 1px solid var(--border-color);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      display: flex;
      flex-direction: column;
      transition: transform 0.25s ease, box-shadow 0.25s ease;
    }

    .gallery-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
    }

    .image-wrapper {
      position: relative;
      width: 100%;
      padding-top: 100%; /* 1:1 Aspect Ratio Guarantee */
      background-color: var(--bg-canvas);
      overflow: hidden;
    }

    .image-wrapper img {
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      object-fit: cover;
      display: block;
      transition: transform 0.4s ease;
    }

    .gallery-card:hover .image-wrapper img {
      transform: scale(1.03);
    }

    .card-info {
      padding: 24px;
      display: flex;
      flex-direction: column;
      flex-grow: 1;
      justify-content: space-between;
    }

    .card-meta {
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 12px;
    }

    .card-step {
      font-size: 12px;
      font-weight: 700;
      color: var(--accent-pop);
      text-transform: uppercase;
      letter-spacing: 0.5px;
      background: #eff6ff;
      padding: 4px 10px;
      border-radius: var(--radius-pill);
    }

    .card-label {
      font-size: 12px;
      font-weight: 600;
      color: var(--text-muted);
    }

    .card-title {
      font-size: 20px;
      font-weight: 700;
      color: var(--text-main);
      margin-bottom: 10px;
      line-height: 1.35;
    }

    .card-desc {
      font-size: 14px;
      color: var(--text-body);
      line-height: 1.6;
      margin-bottom: 16px;
    }

    .card-pills {
      display: flex;
      flex-wrap: wrap;
      gap: 8px;
    }

    .pill-item {
      font-size: 11.5px;
      font-weight: 600;
      padding: 4px 10px;
      background: #f1f5f9;
      color: #475569;
      border-radius: 6px;
    }

    /* ==========================================================================
       Specifications Section
       ========================================================================== */
    .specs-section {
      background: var(--bg-surface);
      border-radius: var(--radius-xl);
      border: 1px solid var(--border-color);
      padding: 40px;
      margin-bottom: 50px;
      box-shadow: var(--shadow-sm);
    }

    .section-header {
      text-align: center;
      margin-bottom: 32px;
    }

    .section-badge {
      display: inline-block;
      font-size: 12px;
      font-weight: 700;
      color: var(--accent-pop);
      text-transform: uppercase;
      letter-spacing: 0.8px;
      margin-bottom: 8px;
    }

    .section-title {
      font-size: 26px;
      font-weight: 800;
      color: var(--text-main);
      letter-spacing: -0.3px;
    }

    .specs-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 20px;
    }

    .spec-card {
      background: var(--bg-surface-soft);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-md);
      padding: 20px;
    }

    .spec-label {
      font-size: 12px;
      font-weight: 600;
      color: var(--text-muted);
      text-transform: uppercase;
      letter-spacing: 0.5px;
      margin-bottom: 6px;
    }

    .spec-value {
      font-size: 16px;
      font-weight: 700;
      color: var(--text-main);
    }

    .spec-sub {
      font-size: 12.5px;
      color: var(--text-body);
      margin-top: 4px;
    }

    /* ==========================================================================
       Interactive FAQ Section (Native <details> Accordion - Zero Links/Buttons)
       ========================================================================== */
    .faq-section {
      background: var(--bg-surface);
      border-radius: var(--radius-xl);
      border: 1px solid var(--border-color);
      padding: 40px;
      box-shadow: var(--shadow-sm);
    }

    .faq-list {
      display: flex;
      flex-direction: column;
      gap: 16px;
      max-width: 900px;
      margin: 0 auto;
    }

    details.faq-item {
      background: var(--bg-surface-soft);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-md);
      overflow: hidden;
      transition: background 0.2s ease, border-color 0.2s ease;
    }

    details.faq-item[open] {
      background: #ffffff;
      border-color: #cbd5e1;
      box-shadow: var(--shadow-sm);
    }

    summary.faq-question {
      padding: 18px 24px;
      font-size: 16px;
      font-weight: 700;
      color: var(--text-main);
      cursor: pointer;
      user-select: none;
      position: relative;
      list-style: none;
      display: flex;
      align-items: center;
      justify-content: space-between;
    }

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

    summary.faq-question::after {
      content: "+";
      font-size: 20px;
      font-weight: 500;
      color: var(--accent-pop);
      transition: transform 0.2s ease;
      margin-left: 12px;
      flex-shrink: 0;
    }

    details.faq-item[open] summary.faq-question::after {
      content: "−";
      color: #64748b;
    }

    .faq-answer {
      padding: 0 24px 20px;
      font-size: 14.5px;
      color: var(--text-body);
      line-height: 1.65;
    }

    /* ==========================================================================
       Responsive Breakpoints
       ========================================================================== */
    @media (max-width: 840px) {
      .specs-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }

    @media (max-width: 680px) {
      .container {
        padding: 24px 16px 60px;
      }
      .hero-section {
        padding: 32px 18px;
        margin-bottom: 28px;
      }
      .hero-title {
        font-size: 25px;
      }
      .hero-desc {
        font-size: 14.5px;
      }
      .gallery-grid {
        grid-template-columns: 1fr;
        gap: 20px;
        margin-bottom: 36px;
      }
      .specs-section, .faq-section {
        padding: 28px 18px;
        margin-bottom: 36px;
      }
      .specs-grid {
        grid-template-columns: 1fr;
        gap: 14px;
      }
      .card-title {
        font-size: 18px;
      }
      summary.faq-question {
        padding: 16px 18px;
        font-size: 15px;
      }
      .faq-answer {
        padding: 0 18px 16px;
        font-size: 14px;
      }
    }