:root {
    --primary-red: #B71C1C;
    --accent-gold: #FFD700;
    --bg-light: #FFF8F8;
    --sidebar-bg: #FFFFFF;
}

body {
    font-family: 'Inter', "Microsoft YaHei", sans-serif;
    background-color: var(--bg-light);
    color: #212529;
    position: relative;
    overflow-x: hidden;
}

/* Watermark */
.watermark {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 9999;
    opacity: 0.04;
    display: flex;
    flex-wrap: wrap;
    justify-content: space-around;
    align-content: space-around;
}

.watermark-text {
    font-size: 2.5rem;
    font-weight: 900;
    transform: rotate(-30deg);
    color: var(--primary-red);
    white-space: nowrap;
    user-select: none;
    margin: 40px;
}

/* Sidebar Styling */
.sidebar {
    position: fixed;
    top: 0;
    bottom: 0;
    left: 0;
    z-index: 100;
    padding: 0;
    box-shadow: inset -1px 0 0 rgba(0, 0, 0, .1);
    background-color: var(--sidebar-bg) !important;
    border-right: 2px solid var(--primary-red);
    transition: transform 0.3s ease-in-out;
}

.sidebar-sticky {
    height: calc(100vh - 48px);
    overflow-x: hidden;
    overflow-y: auto;
}

#sidebarMenu .nav-link {
    font-weight: 600;
    color: #495057;
    padding: 12px 20px;
    border-radius: 8px;
    margin: 5px 15px;
    transition: all 0.2s;
    display: flex;
    align-items: center;
}

#sidebarMenu .nav-link:hover {
    background-color: #fce4e4;
    color: var(--primary-red);
    transform: translateX(5px);
}

#sidebarMenu .nav-link.active {
    background-color: var(--primary-red);
    color: var(--accent-gold) !important;
    box-shadow: 0 4px 6px rgba(183, 28, 28, 0.3);
}

.sidebar-heading {
    font-size: 0.75rem;
    font-weight: 800;
    color: var(--primary-red) !important;
    letter-spacing: 0.1rem;
    padding: 0 2rem;
    margin-top: 1.5rem !important;
    opacity: 0.8;
}

/* Navbar */
.navbar-brand {
    padding-top: .75rem;
    padding-bottom: .75rem;
    font-size: 1rem;
}

.navbar-toggler {
    top: .25rem;
    right: 1rem;
}

/* Content Area */
main {
    background-color: var(--bg-light);
}

#content-area {
    min-height: 80vh;
    line-height: 1.8;
    background: white;
    padding: 2.5rem !important;
    border: none !important;
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    border-radius: 15px;
}

#content-area h3 {
    color: var(--primary-red);
    font-weight: 800;
    margin-bottom: 1.5rem;
    padding-left: 15px;
    border-left: 5px solid var(--accent-gold);
}

#content-area h4 {
    color: var(--primary-red);
    font-weight: 700;
    margin-top: 2rem;
    margin-bottom: 1rem;
}

#content-area h5 {
    color: #333;
    font-weight: 700;
    margin-top: 1.5rem;
    margin-bottom: 0.8rem;
}

/* Image styling in content */
#content-area img {
    max-width: 100%;
    height: auto;
    border-radius: 10px;
    margin: 1rem 0;
    border: 1px solid #eee;
}

/* Footer */
.footer {
    background-color: var(--primary-red);
    color: var(--accent-gold);
    padding: 1rem 0;
    margin-top: 2rem;
    font-weight: 600;
    text-align: center;
}

/* Responsive adjustments */
@media (max-width: 767.98px) {
    .sidebar {
        top: 48px;
        transform: translateX(-100%);
    }
    .sidebar.show {
        transform: translateX(0);
        width: 100%;
        max-width: 280px;
    }
    #content-area {
        padding: 1.5rem !important;
        margin-top: 20px;
    }
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 6px;
}
::-webkit-scrollbar-track {
    background: #f1f1f1;
}
::-webkit-scrollbar-thumb {
    background: var(--primary-red);
    border-radius: 10px;
}

@keyframes fadeIn { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: translateY(0); } } 
.animate-fade-in { animation: fadeIn 0.4s ease-out forwards; }