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

    body {
      background: linear-gradient(145deg, #f0f4fa 0%, #e6edf4 100%);
      font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif;
      padding: 2rem 1.5rem;
      color: #080e14;
    }

    /* main container */
    .app-container {
      max-width: 1400px;
      margin: 0 auto;
    }

    /* header section */
    .hero {
      margin-bottom: 2rem;
      text-align: center;
    }

    .hero h1 {
      font-size: 2.6rem;
      font-weight: 700;
      background: linear-gradient(135deg, #1f4e6e, #2b7a62);
      background-clip: text;
      -webkit-background-clip: text;
      color: transparent;
      letter-spacing: -0.3px;
      margin-bottom: 0.5rem;
    }

    .hero p {
      font-size: 1rem;
      color: #4a627a;
      max-width: 520px;
      margin: 0 auto;
    }

    /* search bar zone */
    .search-wrapper {
      background: white;
      border-radius: 60px;
      box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.05), 0 8px 10px -6px rgba(0, 0, 0, 0.02);
      display: flex;
      align-items: center;
      justify-content: space-between;
      max-width: 700px;
      margin: 1.8rem auto 0 auto;
      padding: 0.3rem 0.3rem 0.3rem 1.5rem;
      border: 1px solid rgba(100, 116, 139, 0.2);
      transition: box-shadow 0.2s, border-color 0.2s;
    }

    .search-wrapper:focus-within {
      box-shadow: 0 18px 30px -12px rgba(31, 78, 110, 0.2);
      border-color: #2b7a6290;
    }

    .search-wrapper input {
      flex: 1;
      border: none;
      padding: 0.9rem 0;
      font-size: 1rem;
      background: transparent;
      outline: none;
      font-weight: 500;
      color: #0b2b38;
    }

    .search-wrapper input::placeholder {
      color: #90a3b9;
      font-weight: 400;
    }

    .search-wrapper button {
      background: #1f4e6e;
      border: none;
      padding: 0.7rem 1.6rem;
      border-radius: 50px;
      color: white;
      font-weight: 600;
      font-size: 0.9rem;
      cursor: pointer;
      transition: all 0.2s ease;
      display: flex;
      align-items: center;
      gap: 8px;
      font-family: inherit;
      letter-spacing: 0.3px;
    }

    .search-wrapper button:hover {
      background: #123a52;
      transform: scale(0.97);
      box-shadow: 0 4px 8px rgba(0, 0, 0, 0.05);
    }

    /* two-column layout */
    .video-layout {
      display: flex;
      flex-wrap: wrap;
      gap: 2rem;
      margin-top: 2.5rem;
    }

    /* main video area (featured) */
    .primary-video {
      flex: 2;
      min-width: 280px;
      background: #ffffffdd;
      backdrop-filter: blur(2px);
      border-radius: 2rem;
      padding: 1rem;
      box-shadow: 0 20px 35px -12px rgba(0, 0, 0, 0.1);
      transition: all 0.2s;
      border: 1px solid rgba(255, 255, 255, 0.6);
    }

    .video-container {
      position: relative;
      width: 100%;
      padding-bottom: 56.25%; /* 16:9 aspect */
      background: #00000010;
      border-radius: 1.2rem;
      overflow: hidden;
      box-shadow: 0 6px 14px rgba(0, 0, 0, 0.1);
    }

    .video-container iframe {
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      border: 0;
      border-radius: 1rem;
    }

    .video-title {
      margin-top: 1rem;
      font-size: 1.45rem;
      font-weight: 700;
      color: #113946;
      padding: 0.3rem 0.2rem;
      display: flex;
      align-items: center;
      gap: 10px;
    }

    .video-title span {
      background: #eef2f8;
      padding: 4px 12px;
      font-size: 0.75rem;
      border-radius: 40px;
      color: #2b6e62;
      font-weight: 500;
    }

    .video-description {
      color: #436277;
      font-size: 0.9rem;
      margin-top: 0.4rem;
      line-height: 1.4;
    }

    /* related videos sidebar */
    .related-sidebar {
      flex: 1.2;
      min-width: 260px;
      background: rgba(255, 255, 255, 0.7);
      backdrop-filter: blur(4px);
      border-radius: 1.8rem;
      padding: 1.2rem 1rem;
      box-shadow: 0 12px 28px -10px rgba(0, 0, 0, 0.08);
      border: 1px solid rgba(255, 255, 255, 0.8);
    }

    .related-header {
      display: flex;
      align-items: baseline;
      justify-content: space-between;
      margin-bottom: 1.2rem;
      padding-bottom: 0.5rem;
      border-bottom: 2px solid #cbdde9;
    }

    .related-header h3 {
      font-size: 1.35rem;
      font-weight: 600;
      color: #1e4a5f;
      letter-spacing: -0.2px;
    }

    .related-header p {
      font-size: 0.75rem;
      background: #e2eaf1;
      padding: 4px 12px;
      border-radius: 40px;
      color: #2c6e5c;
    }

    .related-list {
      display: flex;
      flex-direction: column;
      gap: 1.2rem;
      max-height: 70vh;
      overflow-y: auto;
      padding-right: 0.3rem;
    }

    /* custom scroll */
    .related-list::-webkit-scrollbar {
      width: 5px;
    }

    .related-list::-webkit-scrollbar-track {
      background: #e2e8f0;
      border-radius: 10px;
    }

    .related-list::-webkit-scrollbar-thumb {
      background: #8aaec0;
      border-radius: 10px;
    }

    /* related card item */
    .video-card {
      display: flex;
      gap: 0.9rem;
      background: white;
      border-radius: 1.2rem;
      padding: 0.7rem;
      cursor: pointer;
      transition: all 0.2s ease;
      border: 1px solid #eef2f8;
      box-shadow: 0 2px 5px rgba(0, 0, 0, 0.02);
    }

    .video-card:hover {
      transform: translateY(-3px);
      background: #ffffff;
      border-color: #bcd3e2;
      box-shadow: 0 12px 18px -10px rgba(0, 0, 0, 0.12);
    }

    .thumbnail-placeholder {
      width: 110px;
      height: 70px;
      background: #1f2e3a;
      border-radius: 12px;
      overflow: hidden;
      position: relative;
      flex-shrink: 0;
      background-size: cover;
      background-position: center;
      box-shadow: 0 2px 6px rgba(0,0,0,0.1);
    }

    /* fallback style for thumb using emoji? we'll use inline bg color and icon */
    .thumbnail-placeholder span {
      display: flex;
      align-items: center;
      justify-content: center;
      width: 100%;
      height: 100%;
      font-size: 1.8rem;
      background: #122b36;
      color: white;
    }

    .card-info {
      flex: 1;
    }

    .card-info h4 {
      font-size: 0.9rem;
      font-weight: 700;
      color: #174e5e;
      margin-bottom: 0.2rem;
      line-height: 1.3;
    }

    .card-info p {
      font-size: 0.7rem;
      color: #6b86a0;
      display: flex;
      align-items: center;
      gap: 5px;
    }

    /* no results */
    .no-results {
      text-align: center;
      padding: 2rem;
      color: #6b7f8f;
      font-weight: 500;
      background: #ffffffaa;
      border-radius: 2rem;
    }

    /* responsive touches */
    @media (max-width: 760px) {
      body {
        padding: 1rem;
      }
      .hero h1 {
        font-size: 1.9rem;
      }
      .video-layout {
        flex-direction: column;
      }
      .search-wrapper {
        margin: 1rem 0.5rem;
        padding: 0.2rem 0.2rem 0.2rem 1rem;
      }
      .related-sidebar {
        order: 2;
      }
      .primary-video {
        order: 1;
      }
    }

    .tag-badge {
      font-size: 0.7rem;
      background: #eef2fc;
      padding: 2px 8px;
      border-radius: 30px;
      color: #1e6f5c;
    }

    footer {
      text-align: center;
      margin-top: 3rem;
      font-size: 0.75rem;
      color: #5a7e94;
    }