body {
      display: flex;
      justify-content: center;
      align-items: center;
      height: 100vh;
      background: linear-gradient(135deg, #4facfe, #00f2fe);
      font-family: Arial, sans-serif;
      margin: 0;
      padding: 15px;
    }

    .calculator {
      background: #fff;
      padding: 25px;
      border-radius: 16px;
      box-shadow: 0 6px 16px rgba(0,0,0,0.2);
      text-align: center;
      width: 100%;
      max-width: 400px;
    }

    h2 {
      margin-bottom: 15px;
      color: #333;
      font-size: 22px;
    }

    input, select, button {
      padding: 10px;
      margin: 8px 0;
      border-radius: 8px;
      border: 1px solid #ccc;
      font-size: 16px;
    }

    input, select {
      width: 100%;
      box-sizing: border-box;
    }

    button {
      background: #0077ff;
      color: white;
      cursor: pointer;
      transition: background 0.3s;
      width: 100%;
      border: none;
    }

    button:hover {
      background: #005fcc;
    }

    .selectors {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
    }

    #swap {
      width: 40px;
      flex-shrink: 0;
      font-size: 18px;
      padding: 8px;
      background: #ff9800;
    }

    #swap:hover {
      background: #e68900;
    }

    #result {
      margin-top: 15px;
      font-weight: bold;
      color: #222;
    }

    #status {
      margin-top: 10px;
      font-size: 13px;
      color: gray;
    }

    .history {
      margin-top: 20px;
      text-align: left;
      background: #f9f9f9;
      padding: 12px;
      border-radius: 10px;
      box-shadow: inset 0 2px 6px rgba(0,0,0,0.1);
    }

    .history h4 {
      margin: 0 0 10px;
      color: #333;
      font-size: 16px;
    }

    #historyList {
      list-style: none;
      padding-left: 15px;
      max-height: 120px;
      overflow-y: auto;
    }

    #historyList li {
      font-size: 14px;
      margin-bottom: 6px;
      color: #555;
    }

    /* Flag + select2 alignment */
    .dropdown {
      display: flex;
      align-items: center;
      gap: 6px;
      width: 100%;
    }

    .dropdown img {
      width: 24px;
      height: 18px;
      border-radius: 4px;
      object-fit: cover;
      border: 1px solid #ccc;
    }

    /* Make select2 inputs full width */
    .select2-container {
      flex: 1;
    }

    .select2-selection {
      border-radius: 8px !important;
      height: 40px !important;
      display: flex !important;
      align-items: center !important;
    }

    .select2-selection__rendered {
      font-size: 14px;
      line-height: 40px !important;
    }

    .select2-selection__arrow {
      height: 40px !important;
    }

    /* 🔹 Responsive styles for mobile */
    @media (max-width: 480px) {
      .calculator {
        padding: 20px;
        border-radius: 12px;
      }

      h2 {
        font-size: 18px;
      }

      input, select, button {
        font-size: 14px;
        padding: 8px;
      }

      #swap {
        font-size: 16px;
        width: 35px;
        padding: 6px;
      }

      #result {
        font-size: 15px;
      }

      #status {
        font-size: 12px;
      }

      .history h4 {
        font-size: 14px;
      }

      #historyList li {
        font-size: 13px;
      }
    }

    /* Dark Mode Button */
    #darkModeToggle {
      background: #222;
      color: white;
      border: none;
      padding: 8px 14px;
      border-radius: 8px;
      cursor: pointer;
      font-size: 14px;
      margin-bottom: 15px;
      width: 100%;
    }

    #darkModeToggle:hover {
      background: #444;
    }

    /* Dark Mode Theme */
    body.dark {
      background: linear-gradient(135deg, #1e1e1e, #121212);
      color: white;
    }

    body.dark .calculator {
      background: #1f1f1f;
      color: white;
      box-shadow: 0 6px 16px rgba(255,255,255,0.05);
    }

    body.dark input,
    body.dark select,
    body.dark .select2-selection {
      background: #2c2c2c !important;
      color: white !important;
      border: 1px solid #555 !important;
    }

    body.dark button {
      background: #0077ff;
    }

    body.dark #swap {
      background: #ff9800;
    }

    body.dark .history {
      background: #2a2a2a;
      color: #ddd;
    }

    body.dark #darkModeToggle {
      background: #eee;
      color: #111;
    }

    body.dark #darkModeToggle:hover {
      background: #ccc;
    }