: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: 0.05;
    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: 24px;
    font-weight: bold;
    color: #000;
}

.watermark-item {
    padding: 60px;
    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;
    position: fixed;
    height: 100vh;
    z-index: 1000;
}

#content {
    width: calc(100% - var(--sidebar-width));
    margin-left: var(--sidebar-width);
    padding: 40px;
    transition: all 0.3s;
}

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

.sidebar-header h3 {
    font-size: 1.2rem;
    color: var(--primary-color);
    margin: 0;
}

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

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

#sidebar ul li a:hover, #sidebar ul li.active > a {
    color: #fff;
    background: rgba(212, 175, 55, 0.1);
    border-left: 4px solid var(--primary-color);
}

#sidebar ul li a i {
    margin-right: 10px;
}

/* Floating TG Button */
.tg-float {
    position: fixed;
    right: 30px;
    top: 50%;
    transform: translateY(-50%);
    z-index: 1001;
    text-align: center;
}

.tg-btn {
    width: 60px;
    height: 60px;
    background-color: #0088cc;
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 30px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.3);
    text-decoration: none;
    animation: pulse-tg 2s infinite;
}

.tg-btn:hover {
    color: #fff;
}

.tg-text {
    display: block;
    font-size: 12px;
    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 20px 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: 30px;
    right: 30px;
    display: none;
    z-index: 1001;
}

/* Content Cards */
.card {
    border: none;
    border-radius: 12px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    margin-bottom: 30px;
}

.card-header {
    background: #fff;
    border-bottom: 1px solid #eee;
    font-weight: bold;
    padding: 15px 25px;
}

.step-badge {
    background: var(--primary-color);
    color: #fff;
    padding: 5px 15px;
    border-radius: 20px;
    font-size: 0.8rem;
}

/* Example Sections */
.example-box {
    padding: 20px;
    border-radius: 8px;
    margin-bottom: 20px;
}

.correct-box {
    background-color: #e8f5e9;
    border-left: 5px solid #4caf50;
}

.wrong-box {
    background-color: #ffebee;
    border-left: 5px solid #f44336;
}

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

@media (max-width: 768px) {
    #sidebar { margin-left: -var(--sidebar-width); }
    #sidebar.active { margin-left: 0; }
    #content { width: 100%; margin-left: 0; }
    #content.active { margin-left: var(--sidebar-width); }
}