:root {
    --primary-color: #d4af37;
    --secondary-color: #1a1a1a;
    --text-color: #333;
    --bg-color: #f8f9fa;
    --sidebar-width: 280px;
}

body {
    font-family: 'Inter', "Microsoft YaHei", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    overflow-x: hidden;
}

/* Watermark */
.watermark-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 9999;
    opacity: 0.04;
    overflow: hidden;
}

.watermark-text {
    position: absolute;
    width: 200%;
    height: 200%;
    top: -50%;
    left: -50%;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    align-content: center;
    transform: rotate(-30deg);
    font-size: 20px;
    font-weight: bold;
    color: #000;
}

.watermark-item {
    padding: 80px;
    white-space: nowrap;
}

/* Sidebar Layout */
.wrapper {
    display: flex;
    min-height: 100vh;
}

#sidebar {
    width: var(--sidebar-width);
    background: var(--secondary-color);
    color: #fff;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    position: fixed;
    height: 100vh;
    z-index: 1050;
    box-shadow: 4px 0 10px rgba(0,0,0,0.1);
}

#content {
    width: calc(100% - var(--sidebar-width));
    margin-left: var(--sidebar-width);
    padding: 40px;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Sidebar toggled state (desktop) */
#sidebar.collapsed {
    margin-left: -var(--sidebar-width);
}
#content.expanded {
    width: 100%;
    margin-left: 0;
}

.sidebar-header {
    padding: 30px 25px;
    background: #000;
    text-align: center;
}

.sidebar-header h3 {
    font-size: 1.1rem;
    color: var(--primary-color);
    margin: 0;
    font-weight: 700;
    letter-spacing: 1px;
}

#sidebar ul.components {
    padding: 20px 0;
}

#sidebar ul li a {
    padding: 15px 25px;
    display: block;
    color: #adb5bd;
    text-decoration: none;
    transition: 0.3s;
    font-size: 0.95rem;
}

#sidebar ul li a:hover, #sidebar ul li.active > a {
    color: #fff;
    background: rgba(212, 175, 55, 0.15);
    border-left: 4px solid var(--primary-color);
}

#sidebar ul li a i {
    margin-right: 12px;
}

/* Mobile Nav Bar */
.mobile-nav {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 60px;
    background: var(--secondary-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 15px;
    z-index: 1040;
    box-shadow: 0 2px 10px rgba(0,0,0,0.2);
}

.mobile-logo-text {
    color: var(--primary-color);
    font-weight: bold;
    font-size: 1.1rem;
}

#sidebarCollapseMobile {
    font-size: 1.5rem;
}

/* Overlay */
#overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(0,0,0,0.5);
    z-index: 1045;
    display: none;
    backdrop-filter: blur(2px);
}

/* Floating TG Button */
.tg-float {
    position: fixed;
    right: 25px;
    bottom: 100px;
    z-index: 1001;
    text-align: center;
}

.tg-btn {
    width: 55px;
    height: 55px;
    background-color: #0088cc;
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 28px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.3);
    text-decoration: none;
    animation: pulse-tg 2s infinite;
}

.tg-btn:hover {
    color: #fff;
    transform: scale(1.05);
}

.tg-text {
    display: block;
    font-size: 11px;
    margin-top: 5px;
    background: rgba(0,0,0,0.7);
    color: #fff;
    padding: 2px 8px;
    border-radius: 10px;
}

@keyframes pulse-tg {
    0% { box-shadow: 0 0 0 0 rgba(0, 136, 204, 0.7); }
    70% { box-shadow: 0 0 0 15px rgba(0, 136, 204, 0); }
    100% { box-shadow: 0 0 0 0 rgba(0, 136, 204, 0); }
}

/* Back to Top */
#back-to-top {
    position: fixed;
    bottom: 25px;
    right: 25px;
    display: none;
    z-index: 1001;
    width: 45px;
    height: 45px;
}

/* Content Cards */
.content-card {
    border: none;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.05);
    margin-bottom: 20px;
    overflow: hidden;
}

.card-header {
    background: #fff;
    border-bottom: 1px solid #f0f0f0;
    font-weight: 700;
    padding: 15px 20px;
    font-size: 1rem;
}

.card-body {
    padding: 20px;
}

.text-content {
    font-size: 1.05rem;
    line-height: 1.7;
    color: #444;
}

.step-badge {
    background: var(--primary-color);
    color: #fff;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.75rem;
    vertical-align: middle;
    margin-left: 10px;
}

/* Example Sections */
.example-box {
    padding: 15px;
    border-radius: 10px;
    font-size: 0.95rem;
}

.correct-box {
    background-color: #f1f8f1;
    border-left: 5px solid #28a745;
}

.wrong-box {
    background-color: #fff5f5;
    border-left: 5px solid #dc3545;
}

.explanation-box strong {
    color: #666;
    font-size: 0.85rem;
}

footer {
    padding: 50px 0;
    text-align: center;
    border-top: 1px solid #eee;
    margin-top: 40px;
}

/* Responsive Adjustments */
@media (max-width: 768px) {
    #sidebar { 
        margin-left: -var(--sidebar-width); 
    }
    #sidebar.active { 
        margin-left: 0; 
    }
    #content { 
        width: 100%; 
        margin-left: 0; 
        padding: 80px 15px 20px 15px; 
    }
    
    .section-title-container h2 {
        font-size: 1.4rem;
    }
    
    .card-header {
        padding: 12px 15px;
        font-size: 0.95rem;
    }
    
    .card-body {
        padding: 15px;
    }
    
    .text-content {
        font-size: 0.95rem;
    }
    
    .watermark-item {
        padding: 50px;
    }
    
    .tg-float {
        right: 15px;
        bottom: 80px;
    }
    
    #back-to-top {
        right: 15px;
        bottom: 20px;
    }
}

/* Desktop Hover Effects */
@media (min-width: 769px) {
    .content-card {
        transition: transform 0.2s;
    }
    .content-card:hover {
        transform: translateY(-3px);
    }
}