body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f0f2f5;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

.container {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    text-align: center;
    width: 350px;
}

h1 {
    color: #333;
    margin-bottom: 1.5rem;
}

.balance-container {
    font-size: 2rem;
    font-weight: bold;
    color: #2e7d32; /* Money green */
    margin-bottom: 2rem;
}

.main-btn {
    background-color: #2196f3;
    color: white;
    border: none;
    padding: 20px 40px;
    border-radius: 50%;
    font-size: 1.5rem;
    cursor: pointer;
    transition: transform 0.1s;
    margin-bottom: 2rem;
    width: 120px;
    height: 120px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.2);
}

.main-btn:active {
    transform: scale(0.95);
}

.controls {
    border-top: 1px solid #eee;
    padding-top: 1.5rem;
}

.input-group {
    margin-bottom: 1rem;
    text-align: left;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    color: #666;
    font-size: 0.9rem;
}

input {
    width: 100%;
    padding: 8px;
    border: 1px solid #ddd;
    border-radius: 4px;
    box-sizing: border-box;
}

.secondary-btn {
    background-color: #6772e5; /* Stripe blurple */
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 4px;
    cursor: pointer;
    width: 100%;
    font-weight: bold;
}

.secondary-btn:hover {
    background-color: #5469d4;
}

.note {
    font-size: 0.8rem;
    color: #888;
    margin-top: 0.5rem;
}

#message {
    margin-top: 1rem;
    color: #d32f2f;
    font-size: 0.9rem;
}