/*
 * Global styles for the VietQR generator.
 *
 * The design follows a dark, minimalist theme with navy and blue gradients.
 * It is mobile‑first and responsive, using CSS Flexbox to center the card
 * within the viewport.  Components are spaced generously and use rounded
 * corners for a modern aesthetic.  Feel free to tweak colours or spacing
 * to match your personal preference.
 */

html, body {
    height: 100%;
    margin: 0;
    padding: 0;
    background: linear-gradient(135deg, #05081a, #031f3e);
    color: #ffffff;
}

/* Container centers the card vertically and horizontally */
.container {
    min-height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 1rem;
    box-sizing: border-box;
}

/* Card holds the form and result */
.card {
    background: rgba(9, 22, 48, 0.95);
    border-radius: 1rem;
    padding: 1.5rem;
    width: 100%;
    max-width: 480px;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.4);
    backdrop-filter: blur(10px);
}

.title {
    margin-top: 0;
    margin-bottom: 0.5rem;
    font-size: 1.75rem;
    font-weight: 700;
    color: #00a3e0;
    text-align: center;
}

.subtitle {
    margin-top: 0;
    margin-bottom: 1.5rem;
    font-size: 0.875rem;
    color: #a0b4d2;
    text-align: center;
}

.form-group {
    display: flex;
    flex-direction: column;
    margin-bottom: 1rem;
}

.form-group label {
    font-size: 0.875rem;
    margin-bottom: 0.25rem;
    color: #a0b4d2;
}

.form-group input,
.form-group select {
    background: #0d2847;
    border: 1px solid #1e3e70;
    border-radius: 0.5rem;
    padding: 0.5rem 0.75rem;
    font-size: 1rem;
    color: #fff;
    outline: none;
    transition: border-color 0.2s;
}

.form-group input:focus,
.form-group select:focus {
    border-color: #00a3e0;
}

.btn-primary {
    display: block;
    width: 100%;
    background: linear-gradient(90deg, #0063b1, #00a3e0);
    border: none;
    border-radius: 0.5rem;
    padding: 0.75rem;
    font-size: 1rem;
    font-weight: 600;
    color: #ffffff;
    cursor: pointer;
    transition: background 0.3s;
    margin-top: 0.5rem;
}

.btn-primary:hover {
    background: linear-gradient(90deg, #00549c, #0090c5);
}

.result {
    margin-top: 2rem;
    text-align: center;
}

.qr-image-wrapper {
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 1rem 0;
}

.qr-image-wrapper img {
    max-width: 260px;
    width: 100%;
    height: auto;
    background: #fff;
    padding: 0.5rem;
    border-radius: 0.5rem;
}

.download-btn {
    display: inline-block;
    margin-top: 0.5rem;
    padding: 0.5rem 1rem;
    background: #00a3e0;
    color: #ffffff;
    border-radius: 0.5rem;
    text-decoration: none;
    font-size: 0.875rem;
    transition: background 0.2s;
}

.download-btn:hover {
    background: #0088c4;
}

.footer {
    margin-top: 2rem;
    text-align: center;
    font-size: 0.75rem;
    color: #5b6c8a;
}

/* Responsive tweaks */
@media (min-width: 480px) {
    .title {
        font-size: 2rem;
    }
    .card {
        padding: 2rem;
    }
    .btn-primary {
        padding: 0.75rem 1rem;
        font-size: 1.125rem;
    }
}