* {
    box-sizing: border-box;
}

body {
    margin: 0;
    background: #f3f4f6;
    font-family: Arial, sans-serif;
    color: #111827;
}

.app {
    width: 100%;
    max-width: 650px;
    margin: auto;
    padding: 20px;
}

h1 {
    text-align: center;
    margin-bottom: 25px;
}

.card {
    background: white;
    border-radius: 18px;
    padding: 20px;
    margin-bottom: 15px;
    box-shadow: 0 3px 15px rgba(0,0,0,0.08);
}

h2 {
    font-size: 18px;
    margin-top: 0;
}

input,
select {
    width: 100%;
    padding: 14px;
    border-radius: 10px;
    border: 1px solid #ccc;
    font-size: 16px;
}

button {
    width: 100%;
    padding: 16px;
    border: none;
    border-radius: 12px;
    background: #111827;
    color: white;
    font-size: 17px;
    font-weight: bold;
    margin-bottom: 15px;
}

.preview {
    width: 100%;
    margin-top: 15px;
    border-radius: 12px;
    display: none;
}

.result {
    min-height: 120px;
}

@media (max-width: 500px) {

    .app {
        padding: 12px;
    }

    h1 {
        font-size: 25px;
    }
}