body {
    margin: 0;
    background: #f5f6fa;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

.app {
    width: 360px;
    max-width: 95%;
    padding: 25px;
    background: #ffffff;
    border-radius: 24px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    display: flex;
    flex-direction: column;
    align-items: stretch;
}

h2 {
    font-size: 22px;
    margin-bottom: 20px;
    font-weight: 600;
    text-align: center;
    color: #333;
}

.card {
    background: #fefefe;
    border-radius: 16px;
    padding: 18px;
    margin-bottom: 12px;
    box-shadow: 0 2px 12px rgba(0,0,0,0.06);
    transition: 0.2s;
}

.card:hover {
    box-shadow: 0 6px 18px rgba(0,0,0,0.08);
}

.row {
    display: flex;
    align-items: center;
    gap: 12px;
}

.flag {
    width: 36px;
    height: 26px;
    border-radius: 6px;
    object-fit: cover;
    border: 1px solid #ddd;
}

select {
    font-size: 16px;
    padding: 6px;
    border-radius: 8px;
    border: 1px solid #ddd;
    flex: 1;
}

.amount {
    font-size: 36px;
    font-weight: bold;
    margin-top: 12px;
    text-align: right;
    color: #222;
}

.rate {
    text-align: right;
    font-size: 15px;
    color: #666;
    margin: 8px 0 16px;
}

.keypad {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
    margin-top: 20px;
}

.keypad button {
    background: #fff;
    border: none;
    padding: 18px 0;
    font-size: 26px;
    border-radius: 16px;
    cursor: pointer;
    box-shadow: 0 3px 12px rgba(0,0,0,0.08);
    transition: 0.1s, box-shadow 0.2s;
}

.keypad button:hover {
    box-shadow: 0 5px 18px rgba(0,0,0,0.1);
}

.keypad button:active {
    transform: scale(0.95);
}

.keypad .icon {
    font-size: 22px;
}

.next {
    width: 100%;
    margin-top: 25px;
    padding: 16px;
    background: linear-gradient(135deg, #2d6cdf, #3ea0ff);
    color: white;
    font-size: 20px;
    border-radius: 14px;
    border: none;
    cursor: pointer;
    transition: 0.1s, box-shadow 0.2s;
    box-shadow: 0 5px 18px rgba(0,0,0,0.12);
}

.next:hover {
    box-shadow: 0 7px 22px rgba(0,0,0,0.15);
}

.next:active {
    transform: scale(0.97);
}

@media (max-width: 400px) {
    .app {
        width: 95%;
        padding: 20px;
    }
    .amount {
        font-size: 28px;
    }
    .keypad button {
        font-size: 22px;
        padding: 16px 0;
    }
    .next {
        font-size: 18px;
        padding: 14px;
    }
}

.keypad .key-img {
    width: 24px;
    height: 24px;
    object-fit: contain;
}