body {
    font-family: Arial, sans-serif;
    background-color: #fcecec;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

.container {
    background-color: #fff;
    padding: 25px;
    border-radius: 10px;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
    width: 280px;
    text-align: center;
}

input {
    width: 90%;
    padding: 8px;
    margin: 8px 0;
    border: 1px solid #ccc;
    border-radius: 5px;
}

button {
    background-color: #e53935;
    color: #fff;
    border: none;
    padding: 10px 15px;
    border-radius: 5px;
    cursor: pointer;
    margin-top: 15px;
}


button:hover {
    background-color: #c62828;
}

.sonuc-kutu {
    margin-top: 20px;
    background-color: #f9f9f9;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0,0,0,0.05);
  }
  
.invalid {
    border: 2px solid #d32f2f;
    background-color: #fff0f0;
  }
  
  .result.error {
    color: #d32f2f;
    font-weight: bold;
  }
  
  .harf {
    font-size: 1.6em;
    font-weight: 600;
    color: #444;
    margin-top: 10px;
  }
  
@media (max-width: 480px) {
    .container {
        width: 90%;
        padding: 20px;
    }

    input,
    button {
        font-size: 1em;
    }

    h2 {
        font-size: 1.2em;
    }
}