:root {
    --card: #0a013300;
    --text: #f0f0f0;
    --accent: #00bfa6;
    --accent-hover: #009e8c;
    --gray: #ccc;
  }
  
  * {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', sans-serif;
  }
  
  body {
    color: var(--text);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 2rem;
  }
  
  .container {
    background-color: var(--card);
    padding: 2rem;
    border-radius: 1rem;
    max-width: 400px;
    width: 100%;
    text-align: center;
    box-shadow: 0 0 20px rgba(0,0,0,0.6);
  }
  
  header h1 {
    font-size: 2rem;
    color: var(--accent);
    margin-bottom: 0.5rem;
  }
  
  header p {
    font-size: 0.95rem;
    color: var(--gray);
    margin-bottom: 2rem;
  }
  
  .converter-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
  }
  /* Greys out the entire dropdown */
.custom-dropdown.disabled {
    opacity: 0.5;
    pointer-events: none;
  }
  
  /* Greys out the button */
  .convert-button[disabled] {
    background-color: #444;
    color: #888;
    cursor: not-allowed;
  }
  
  .file-label {
    background-color: #2a2a2a;
    padding: 1rem;
    border-radius: 8px;
    border: 2px dashed var(--gray);
    cursor: pointer;
    transition: border 0.3s ease;
    color: var(--gray);
    width: -webkit-fill-available;
  }
  
  .file-label:hover {
    border-color: var(--accent);
  }
  
  .file-label input {
    display: none;
  }
  .dropdown-wrapper {
    position: relative;
    text-align: left;
  }
  
  .custom-dropdown {
    background-color: #2a2a2a;
    border-radius: 6px;
    position: relative;
    user-select: none;
  }
  
  .custom-dropdown .selected {
    padding: 0.8rem;
    color: var(--text);
    cursor: pointer;
    border: 2px solid #333;
    border-radius: 6px;
  }
  
  .custom-dropdown .dropdown-options {
    display: none;
    position: absolute;
    width: 100%;
    max-height: 250px;
    overflow-y: auto;
    background-color: #1f1f1f;
    border: 1px solid #333;
    border-radius: 0 0 6px 6px;
    z-index: 10;
    margin-top: 4px;
  }
  
  .custom-dropdown.open .dropdown-options {
    display: block;
  }
  
  .dropdown-group {
    padding: 0.5rem;
  }
  
  .group-title {
    color: var(--accent);
    font-size: 0.85rem;
    margin-bottom: 0.3rem;
    padding-left: 0.5rem;
  }
  
  .option {
    padding: 0.5rem 0.8rem;
    color: var(--text);
    cursor: pointer;
    border-radius: 4px;
  }
  
  div.option:hover {
    background-color: #131313;
  }
  
  
  .convert-button {
    margin-top: 1em;
    padding: 0.8rem;
    background-color: var(--accent);
    color: #fff;
    border: none;
    border-radius: 6px;
    font-weight: bold;
    cursor: pointer;
    transition: background 0.3s ease;
    width: -webkit-fill-available;
  }
  
  .convert-button:hover {
    background-color: var(--accent-hover);
  }
  
  footer {
    margin-top: 2rem;
    font-size: 0.8rem;
    color: #777;
  }
  
  /* Mobile optimization */
  @media (max-width: 500px) {
    .container {
      padding: 1.5rem;
    }
  
    header h1 {
      font-size: 1.6rem;
    }
  }

  
  .file-input-group {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    margin-bottom: 1.5rem;
    color: var(--text);
  }
  
  .file-label {
    font-weight: bold;
    margin-bottom: 0.5rem;
    color: var(--accent);
  }
  
  .file-name {
    margin-top: 0.5rem;
    font-size: 0.9rem;
    color: #ccc;
    background-color: #1f1f1f;
    padding: 0.5rem;
    border-radius: 4px;
    width: 100%;
    word-wrap: break-word;
  }
  
  /* Style for greyed-out options */
.option.disabled {
    opacity: 0.5;
    pointer-events: none; /* Prevent clicking */
    background-color: #444;
  }