@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@400;600&display=swap');

    * {
      box-sizing: border-box;
    }

    body, html {
      margin: 0;
      padding: 0;
      height: 100%;
      font-family: 'Poppins', sans-serif;
      background: linear-gradient(135deg, #f0f4ff, #ffffff);
      color: #222;
      display: flex;
      justify-content: center;
      align-items: center;
      overflow: hidden;
    }

    .container {
      background: #fff;
      border-radius: 24px;
      box-shadow:
        0 8px 24px rgba(0, 0, 0, 0.12),
        0 0 0 4px #e6f0ff;
      width: 400px;
      max-width: 90vw;
      padding: 3rem 2.5rem 3.5rem;
      text-align: center;
      position: relative;
      overflow: hidden;
      transition: box-shadow 0.3s ease;
    }

    .container:hover {
      box-shadow:
        0 12px 36px rgba(0, 0, 0, 0.18),
        0 0 0 6px #c3d7ff;
    }

    h1 {
      margin-bottom: 1.2rem;
      font-weight: 700;
      font-size: 2.2rem;
      color: #1a237e;
      letter-spacing: 0.04em;
      text-shadow: 0 1px 3px rgba(26, 35, 126, 0.3);
    }

    label {
      display: block;
      text-align: left;
      font-weight: 600;
      margin-bottom: 0.6rem;
      font-size: 1.1rem;
      color: #3949ab;
      user-select: none;
    }

    input[type="number"] {
      width: 100%;
      padding: 0.85rem 1.2rem;
      font-size: 1.2rem;
      border: 2.5px solid #c5cae9;
      border-radius: 16px;
      transition: border-color 0.3s ease, box-shadow 0.3s ease;
      outline-offset: 3px;
      font-weight: 500;
      color: #1a237e;
      background: #f7f9ff;
      box-shadow: inset 0 2px 6px rgba(26, 35, 126, 0.05);
    }

    input[type="number"]::placeholder {
      color: #9fa8da;
      font-weight: 400;
    }

    input[type="number"]:focus {
      border-color: #3f51b5;
      box-shadow: 0 0 8px #7986cb88;
      outline: none;
      background: #e8ebff;
    }

    button {
      margin-top: 2rem;
      width: 100%;
      padding: 1rem;
      font-size: 1.25rem;
      font-weight: 700;
      color: #fff;
      background: linear-gradient(135deg, #3949ab, #1a237e);
      border: none;
      border-radius: 20px;
      cursor: pointer;
      box-shadow: 0 8px 20px rgba(26, 35, 126, 0.5);
      transition: background 0.3s ease, box-shadow 0.3s ease;
      user-select: none;
      letter-spacing: 0.05em;
      text-transform: uppercase;
    }

    button:hover:not(:disabled) {
      background: linear-gradient(135deg, #1a237e, #121858);
      box-shadow: 0 10px 28px rgba(18, 24, 88, 0.7);
    }

    button:disabled {
      background: #9fa8da;
      cursor: not-allowed;
      box-shadow: none;
    }

    .qris-container {
      margin-top: 2.5rem;
      min-height: 320px;
      display: flex;
      flex-direction: column;
      justify-content: center;
      align-items: center;
      position: relative;
      border-radius: 24px;
      background: #f0f4ff;
      box-shadow: inset 0 0 20px #c5cae9;
      padding: 1rem 1.5rem 2rem;
      overflow: hidden;
    }

    .qris-container img {
      max-width: 280px;
      max-height: 280px;
      border-radius: 20px;
      box-shadow: 0 12px 36px rgba(26, 35, 126, 0.25);
      opacity: 0;
      transform: scale(0.85);
      animation: fadeInScale 0.6s forwards;
      user-select: none;
    }

    @keyframes fadeInScale {
      to {
        opacity: 1;
        transform: scale(1);
      }
    }

    .loading-spinner {
      border: 6px solid #d1d9ff;
      border-top: 6px solid #3949ab;
      border-radius: 50%;
      width: 56px;
      height: 56px;
      animation: spin 1s linear infinite;
      margin: auto;
      box-shadow: 0 0 12px #3949ab88;
    }

    @keyframes spin {
      to { transform: rotate(360deg); }
    }

    .error-message {
      color: #e53935;
      font-weight: 700;
      margin-top: 1.2rem;
      font-size: 1rem;
      user-select: none;
      letter-spacing: 0.02em;
    }

    .countdown {
      margin-top: 1rem;
      font-weight: 600;
      font-size: 1rem;
      color: #3949ab;
      user-select: none;
      letter-spacing: 0.03em;
    }

    .download-btn {
      margin-top: 1.5rem;
      padding: 0.75rem 1.8rem;
      font-size: 1rem;
      font-weight: 600;
      color: #3949ab;
      background: #e3e9ff;
      border: 2px solid #3949ab;
      border-radius: 16px;
      cursor: pointer;
      transition: background 0.3s ease, color 0.3s ease;
      user-select: none;
      align-self: center;
      text-transform: none;
      box-shadow: 0 4px 12px rgba(57, 73, 171, 0.3);
    }

    .download-btn:hover {
      background: #3949ab;
      color: #fff;
      box-shadow: 0 6px 20px rgba(57, 73, 171, 0.6);
    }

    footer {
      margin-top: 3rem;
      font-size: 0.85rem;
      color: #9fa8da;
      user-select: none;
    }

    /* Subtle floating background circles */
    .background-circles {
      position: fixed;
      top: 0; left: 0; right: 0; bottom: 0;
      pointer-events: none;
      z-index: -1;
      overflow: visible;
    }

    .circle {
      position: absolute;
      border-radius: 50%;
      background: radial-gradient(circle at center, #7986cb44, transparent 70%);
      animation: floatUpDown 6s ease-in-out infinite alternate;
      filter: blur(12px);
    }

    .circle.small {
      width: 80px;
      height: 80px;
      bottom: 10%;
      left: 15%;
      animation-delay: 0s;
    }

    .circle.medium {
      width: 140px;
      height: 140px;
      top: 20%;
      right: 10%;
      animation-delay: 2s;
    }

    .circle.large {
      width: 220px;
      height: 220px;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      animation-delay: 4s;
    }

    @keyframes floatUpDown {
      0% {
        transform: translateY(0);
        opacity: 0.6;
      }
      100% {
        transform: translateY(-20px);
        opacity: 0.4;
      }
    }

    @media (max-width: 440px) {
      .container {
        width: 90vw;
        padding: 2.5rem 1.8rem 3rem;
      }

      h1 {
        font-size: 1.8rem;
      }

      button {
        font-size: 1.1rem;
        padding: 0.9rem;
      }

      .qris-container {
        min-height: 280px;
      }

      .qris-container img {
        max-width: 220px;
        max-height: 220px;
      }
    }