body {
    background: #f5f7fb;
    min-height: 100vh;
}

.app-card {
    border: 0;
    border-radius: 1rem;
    box-shadow: 0 0.5rem 1.4rem rgba(15, 23, 42, 0.08);
}

.qr-preview-box {
    border: 1px dashed #cbd5e1;
    border-radius: 0.9rem;
    min-height: 240px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: #ffffff;
    padding: 1rem;
}

.qr-preview-box img {
    max-width: 100%;
    height: auto;
}

.muted-tip {
    color: #64748b;
    font-size: 0.95rem;
}