/* roulang page: index */
:root {
      --primary-deep: #1A3C34;
      --primary-dark: #2C3E50;
      --accent-green: #00C896;
      --accent-amber: #F39C12;
      --bg-light: #F8F9FA;
      --bg-cool-gray: #ECF0F1;
      --text-dark: #1e2b2a;
      --text-muted: #5a6c6b;
      --text-light-on-dark: #d0d7d6;
      --border-light: #e0e5e4;
      --white: #ffffff;
      --card-shadow: 0 2px 12px rgba(0, 0, 0, 0.04);
      --card-shadow-hover: 0 8px 24px rgba(0, 0, 0, 0.08);
      --border-radius-card: 12px;
      --border-radius-btn: 6px;
      --transition-base: all 0.25s ease;
    }

    * {
      box-sizing: border-box;
    }

    body {
      font-family: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
      background-color: var(--bg-light);
      color: var(--text-dark);
      line-height: 1.7;
      font-size: 16px;
      margin: 0;
      padding: 0;
      overflow-x: hidden;
    }

    h1, h2, h3, h4, .card-title, .nav-brand {
      font-weight: 700;
      letter-spacing: -0.2px;
    }

    h1 {
      font-size: 2.6rem;
      line-height: 1.25;
    }

    h2 {
      font-size: 1.9rem;
    }

    h3 {
      font-size: 1.35rem;
    }

    a {
      color: var(--accent-green);
      text-decoration: none;
      transition: var(--transition-base);
    }

    a:hover {
      color: #00a87a;
    }

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

    .container {
      max-width: 1140px;
      padding-left: 20px;
      padding-right: 20px;
    }

    /* utility bar */
    .utility-bar {
      background-color: var(--primary-dark);
      color: var(--text-light-on-dark);
      font-size: 0.85rem;
      padding: 8px 0;
      letter-spacing: 0.3px;
    }
    .utility-bar a.utility-btn {
      background-color: var(--accent-green);
      color: #fff;
      padding: 4px 16px;
      border-radius: 20px;
      font-weight: 600;
      font-size: 0.8rem;
      margin-left: 16px;
      transition: var(--transition-base);
    }
    .utility-bar a.utility-btn:hover {
      background-color: #00b386;
      color: #fff;
    }

    /* main navigation */
    .navbar {
      background-color: #fff;
      box-shadow: 0 4px 12px rgba(0,0,0,0.02);
      padding: 12px 0;
    }
    .navbar-brand {
      font-size: 1.8rem;
      font-weight: 700;
      color: var(--primary-deep) !important;
      letter-spacing: 0.5px;
    }
    .navbar-brand span {
      color: var(--accent-green);
    }
    .nav-link {
      color: var(--text-dark) !important;
      font-weight: 500;
      margin: 0 8px;
      padding: 6px 2px !important;
      border-bottom: 2px solid transparent;
      transition: var(--transition-base);
    }
    .nav-link:hover, .nav-link.active {
      color: var(--accent-green) !important;
      border-bottom-color: var(--accent-green);
    }
    .navbar-toggler {
      border: none;
      color: var(--primary-deep);
    }

    /* buttons */
    .btn-primary-custom {
      background-color: var(--accent-green);
      border: none;
      color: #fff;
      font-weight: 600;
      padding: 12px 28px;
      border-radius: var(--border-radius-btn);
      letter-spacing: 0.5px;
      font-size: 0.95rem;
      transition: var(--transition-base);
      box-shadow: 0 2px 6px rgba(0,200,150,0.2);
    }
    .btn-primary-custom:hover {
      background-color: #00b386;
      color: #fff;
      box-shadow: 0 4px 12px rgba(0,180,130,0.3);
      transform: translateY(-1px);
    }
    .btn-outline-custom {
      background: transparent;
      border: 2px solid var(--primary-dark);
      color: var(--primary-dark);
      font-weight: 600;
      padding: 10px 26px;
      border-radius: var(--border-radius-btn);
      letter-spacing: 0.5px;
      font-size: 0.95rem;
      transition: var(--transition-base);
    }
    .btn-outline-custom:hover {
      background-color: var(--primary-dark);
      color: #fff;
      border-color: var(--primary-dark);
    }

    /* hero section */
    .hero {
      background: linear-gradient(135deg, #f0f5f4 0%, #ffffff 100%);
      padding: 70px 0 80px;
      position: relative;
      overflow: hidden;
    }
    .hero::before {
      content: "";
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background-image: url('/assets/images/backpic/back-1.webp');
      background-size: cover;
      background-position: center;
      opacity: 0.08;
      pointer-events: none;
    }
    .hero-image {
      border-radius: 20px;
      box-shadow: 0 15px 30px rgba(0,0,0,0.08);
    }

    /* section spacing */
    .section-padding {
      padding: 80px 0;
    }

    /* advantage cards */
    .advantage-card {
      background: #fff;
      border-radius: var(--border-radius-card);
      padding: 2rem 1.5rem;
      box-shadow: var(--card-shadow);
      transition: var(--transition-base);
      height: 100%;
      border: 1px solid var(--border-light);
    }
    .advantage-card:hover {
      box-shadow: var(--card-shadow-hover);
      transform: translateY(-3px);
    }
    .advantage-icon {
      width: 50px;
      height: 50px;
      background-color: rgba(0,200,150,0.1);
      color: var(--accent-green);
      border-radius: 12px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 1.5rem;
      margin-bottom: 1.2rem;
    }

    /* product cards masonry style */
    .product-card {
      background: #fff;
      border-radius: var(--border-radius-card);
      overflow: hidden;
      box-shadow: var(--card-shadow);
      transition: var(--transition-base);
      margin-bottom: 24px;
      break-inside: avoid;
      border: 1px solid var(--border-light);
    }
    .product-card:hover {
      box-shadow: var(--card-shadow-hover);
      transform: translateY(-3px);
    }
    .product-card img {
      width: 100%;
      height: 180px;
      object-fit: cover;
    }
    .product-card .card-body {
      padding: 1.5rem;
    }
    .badge-tag {
      background-color: rgba(0,200,150,0.12);
      color: var(--primary-deep);
      font-weight: 600;
      font-size: 0.7rem;
      padding: 4px 10px;
      border-radius: 20px;
      margin-right: 6px;
      letter-spacing: 0.3px;
    }

    /* compare block */
    .compare-col-bad {
      background-color: #f9f3f0;
      border-left: 4px solid #e0a58a;
    }
    .compare-col-good {
      background-color: #eef8f4;
      border-left: 4px solid var(--accent-green);
    }
    .compare-icon-fail {
      color: #c0392b;
    }
    .compare-icon-pass {
      color: var(--accent-green);
    }

    /* faq accordion */
    .accordion-button:not(.collapsed) {
      background-color: #f4faf8;
      color: var(--accent-green);
      font-weight: 700;
      box-shadow: none;
    }
    .accordion-button:focus {
      border-color: var(--accent-green);
      box-shadow: 0 0 0 0.15rem rgba(0,200,150,0.25);
    }
    .accordion-item {
      border-left: none;
      border-right: none;
      border-top: 1px solid var(--border-light);
    }

    /* cta banner */
    .cta-banner {
      background-color: var(--primary-deep);
      background-image: url('/assets/images/backpic/back-2.webp');
      background-size: cover;
      background-position: center;
      background-blend-mode: overlay;
      padding: 70px 0;
      text-align: center;
    }

    /* footer */
    .footer {
      background-color: #1b2b28;
      color: #b0bfbc;
      padding: 50px 0 30px;
    }
    .footer a {
      color: #cfdcd9;
      text-decoration: none;
    }
    .footer a:hover {
      color: var(--accent-green);
    }
    .footer h5 {
      color: #fff;
      font-weight: 700;
      margin-bottom: 1.2rem;
    }

    @media (max-width: 768px) {
      h1 {
        font-size: 2rem;
      }
      .hero {
        padding: 40px 0 50px;
        text-align: center;
      }
      .hero .btn {
        display: block;
        width: 100%;
        margin-bottom: 10px;
      }
      .navbar-collapse {
        background: #fff;
        padding: 20px;
        border-radius: 12px;
      }
    }