* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: Arial, sans-serif;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    height: 100vh;
    background: #f0f2f5;
    text-align: center;
    gap: 10px;
}

.container {
    background: #fff;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    text-align: center;
}

#header {
    margin-bottom: 20px;
    font-size: 24px;
    color: #333;
    transition: color 0.3s ease;
}

.input-group {
    margin-bottom: 15px;
}

label {
    display: block;
    margin-bottom: 5px;
    font-weight: bold;
}

input, select {
    width: 100%;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 5px;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

input:focus, select:focus {
    border-color: #007bff;
    box-shadow: 0 0 8px rgba(0, 123, 255, 0.25);
}

#exchange {
    margin-top: 20px;
    font-size: 18px;
    font-weight: bold;
    color: #007bff;
    transition: opacity 0.3s ease;
}

#exchange.fade-in {
    opacity: 1;
    animation: fadeIn 0.5s ease-in-out;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}