:root {
    /* Light Theme (Default) */
    --bg-color: #ffffff;
    --surface-color: #f8f9fa;
    --text-color: #212529;
    --heading-color: #000080; /* Navy Blue */
    --primary-color: #000080; /* Navy Blue */
    --primary-hover: #000050;
    --border-color: #dee2e6;
    --contrast-bg: #000000; /* Black contrast */
    --contrast-text: #ffffff;
}

[data-theme="lighter"] {
    /* Lighter (Grey) Theme */
    --bg-color: #e0e0e0; /* Light Grey */
    --surface-color: #cccccc; /* Medium Light Grey */
    --text-color: #1a1a1a;
    --heading-color: #000080; /* Navy Blue */
    --primary-color: #000080; /* Navy Blue */
    --primary-hover: #000050;
    --border-color: #b3b3b3;
    --contrast-bg: #000000; /* Black contrast */
    --contrast-text: #ffffff;
}

[data-theme="dark"] {
    /* Dark Theme */
    --bg-color: #121212; /* Dark Grey */
    --surface-color: #1e1e1e; /* Darker Grey */
    --text-color: #e0e0e0;
    --heading-color: #4a90e2; /* Lighter blue for dark mode readability */
    --primary-color: #000080; /* Navy Blue */
    --primary-hover: #000050;
    --border-color: #333333;
    --contrast-bg: #000000; /* Black contrast */
    --contrast-text: #ffffff;
}

/* Apply Variables */
body {
    background-color: var(--bg-color) !important;
    color: var(--text-color) !important;
    font-size: 16px;
    line-height: 1.6;
    transition: background-color 0.3s, color 0.3s;
}

/* Container Scaling for varying screen sizes */
.container, .container-fluid {
    padding-left: 15px;
    padding-right: 15px;
}
@media (min-width: 768px) {
    .container { max-width: 95%; }
}
@media (min-width: 1200px) {
    .container { max-width: 90%; }
    body { font-size: 18px; }
}
@media (min-width: 1600px) {
    .container { max-width: 1400px; }
}

/* Navbar */
.navbar {
    background-color: var(--surface-color) !important;
    border-bottom: 2px solid var(--contrast-bg);
}
.navbar-brand, .nav-link {
    color: var(--text-color) !important;
}
.nav-link:hover, .nav-link.active {
    color: var(--primary-color) !important;
    font-weight: bold;
}

/* Cards */
.card {
    background-color: var(--surface-color) !important;
    border: 1px solid var(--border-color) !important;
    color: var(--text-color) !important;
    transition: transform 0.3s ease, box-shadow 0.3s ease, background-color 0.3s;
}
.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.2);
}
.card-title {
    color: var(--heading-color) !important;
}

/* Headings */
h1, h2, h3, h4, h5, h6 {
    color: var(--heading-color) !important;
}

/* Badges */
.bg-primary {
    background-color: var(--primary-color) !important;
    color: #ffffff !important;
}

/* Buttons */
.btn-primary, .btn-outline-primary {
    background-color: var(--primary-color) !important;
    color: #ffffff !important;
    border: 1px solid var(--contrast-bg) !important;
}
.btn-primary:hover, .btn-outline-primary:hover {
    background-color: var(--primary-hover) !important;
    color: #ffffff !important;
}

/* Accordion */
.accordion-button {
    background-color: var(--surface-color) !important;
    color: var(--text-color) !important;
    border-bottom: 1px solid var(--border-color);
}
.accordion-button:not(.collapsed) {
    background-color: var(--primary-color) !important;
    color: #ffffff !important;
}
.accordion-item {
    background-color: var(--surface-color) !important;
    border-color: var(--border-color) !important;
}
.accordion-body {
    color: var(--text-color) !important;
}

/* Modal */
.modal-content {
    background-color: var(--surface-color) !important;
    color: var(--text-color) !important;
    border: 2px solid var(--contrast-bg);
}
.modal-header {
    border-bottom: 1px solid var(--border-color);
}
.modal-footer {
    border-top: 1px solid var(--border-color);
}

/* Forms */
.form-control {
    background-color: var(--bg-color) !important;
    color: var(--text-color) !important;
    border: 1px solid var(--border-color) !important;
}
.form-control:focus {
    border-color: var(--primary-color) !important;
    box-shadow: 0 0 0 0.25rem rgba(0, 0, 128, 0.25) !important;
}

/* Carousel Caption */
.carousel-caption {
    background: rgba(0, 0, 0, 0.7) !important;
    color: #ffffff !important;
    border: 1px solid var(--contrast-bg);
}
.carousel-caption h5 {
    color: #ffffff !important;
}

/* Footer */
footer {
    background-color: var(--surface-color) !important;
    color: var(--text-color) !important;
    border-top: 2px solid var(--contrast-bg);
}