:root {
    --primary-color: #4361ee;
    --secondary-color: #3f37c9;
    --accent-color: #4cc9f0;
    --light-color: #f8f9fa;
    --dark-color: #212529;
    --success-color: #4bb543;
    
    /* Light mode colors */
    --bg-color: #f5f7ff;
    --text-color: #212529;
    --card-bg: #ffffff;
    --footer-bg: #212529;
    --footer-text: #ffffff;
    --input-bg: #ffffff;
    --input-border: #ced4da;
    --qr-placeholder: #e9ecef;
}

[data-bs-theme="dark"] {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --card-bg: #1e1e1e;
    --footer-bg: #000000;
    --footer-text: #e0e0e0;
    --input-bg: #2d2d2d;
    --input-border: #444;
    --qr-placeholder: #2d2d2d;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.navbar {
    background-color: var(--card-bg) !important;
    transition: background-color 0.3s ease;
}

.navbar-brand {
    font-weight: 700;
    color: var(--primary-color);
}

.hero-section {
    background: linear-gradient(135deg, #4361ee 0%, #3a0ca3 100%);
    color: white;
    padding: 4rem 0;
    border-radius: 0 0 20px 20px;
    box-shadow: 0 10px 30px rgba(67, 97, 238, 0.2);
}

.hero-title {
    font-weight: 800;
    font-size: 2.8rem;
    margin-bottom: 1rem;
}

.hero-subtitle {
    font-weight: 400;
    font-size: 1.2rem;
    opacity: 0.9;
    margin-bottom: 2rem;
}

.card {
    background-color: var(--card-bg);
    border: none;
    border-radius: 15px;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.05);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    overflow: hidden;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.1);
}

.card-header {
    background-color: var(--primary-color);
    color: white;
    font-weight: 600;
    padding: 1rem 1.5rem;
}

.btn-primary {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
    padding: 0.5rem 1.5rem;
    font-weight: 500;
}

.btn-primary:hover {
    background-color: var(--secondary-color);
    border-color: var(--secondary-color);
}

.btn-outline-primary {
    color: var(--primary-color);
    border-color: var(--primary-color);
}

.btn-outline-primary:hover {
    background-color: var(--primary-color);
    color: white;
}

.form-control, .form-select {
    background-color: var(--input-bg);
    color: var(--text-color);
    padding: 0.75rem 1rem;
    border-radius: 10px;
    border: 1px solid var(--input-border);
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.form-control:focus, .form-select:focus {
    background-color: var(--input-bg);
    color: var(--text-color);
    border-color: var(--primary-color);
    box-shadow: 0 0 0 0.25rem rgba(67, 97, 238, 0.25);
}

.qr-code-container {
    background-color: var(--card-bg);
    border-radius: 10px;
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 300px;
    border: 1px dashed var(--input-border);
}

#qrCode {
    width: 200px;
    height: 200px;
    margin-bottom: 1.5rem;
}

.feature-icon {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.feature-title {
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.feature-description {
    color: #6c757d;
}

.footer {
    background-color: var(--footer-bg);
    color: var(--footer-text);
    padding: 3rem 0;
}

.footer-title {
    font-weight: 700;
    margin-bottom: 1.5rem;
}

.footer-links a {
    color: #adb5bd;
    text-decoration: none;
    display: block;
    margin-bottom: 0.5rem;
    transition: color 0.3s ease;
}

.footer-links a:hover {
    color: var(--accent-color);
}

.social-icons a {
    color: var(--footer-text);
    font-size: 1.5rem;
    margin-right: 1rem;
    transition: color 0.3s ease;
}

.social-icons a:hover {
    color: var(--accent-color);
}

.copyright {
    border-top: 1px solid #495057;
    padding-top: 1.5rem;
    margin-top: 2rem;
    color: #adb5bd;
}

.tab-content {
    padding: 1.5rem 0;
}

.nav-tabs .nav-link {
    color: var(--text-color);
    font-weight: 500;
    border: none;
    padding: 0.75rem 1.5rem;
    background-color: transparent;
}

.nav-tabs .nav-link.active {
    color: var(--primary-color);
    background-color: transparent;
    border-bottom: 3px solid var(--primary-color);
}

.nav-tabs .nav-link:hover:not(.active) {
    color: var(--primary-color);
}

.download-btn-group .btn {
    margin-right: 0.5rem;
    margin-bottom: 0.5rem;
}

.color-preview {
    width: 25px;
    height: 25px;
    display: inline-block;
    border-radius: 50%;
    margin-right: 0.5rem;
    border: 1px solid var(--input-border);
}

#qrPlaceholder i {
    color: var(--qr-placeholder) !important;
}

/* Dark mode toggle button */
.dark-mode-toggle {
    background: none;
    border: none;
    color: var(--text-color);
    font-size: 1.25rem;
    cursor: pointer;
    padding: 0.5rem;
    margin-left: 0.5rem;
    transition: transform 0.3s ease;
}

.dark-mode-toggle:hover {
    transform: rotate(30deg);
}

.accordion-button {
    background-color: var(--card-bg);
    color: var(--text-color);
}

.accordion-button:not(.collapsed) {
    background-color: var(--card-bg);
    color: var(--primary-color);
}

.accordion-body {
    background-color: var(--card-bg);
}

@media (max-width: 768px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .nav-tabs .nav-link {
        padding: 0.5rem 1rem;
        font-size: 0.9rem;
    }
}