@import url('https://fonts.googleapis.com/css2?family=Noto+Serif+SC:wght@500;700&display=swap');
:root {
    --bg-paper: #faf8f5;
    --win-white: #ffffff;
    --text-dark: #2c2a29;
    --text-muted: #807a75;
    --accent-forest: #384e43;
    --border-fine: 1px solid rgba(0, 0, 0, 0.04);
}
body {
    background-color: var(--bg-paper);
    color: var(--text-dark);
    font-family: "Noto Serif SC", "STSong", "SimSun", serif;
    margin: 0;
    padding: 0;
}
.birch-header {
    background: var(--win-white);
    border-bottom: var(--border-fine);
    height: 65px;
    position: sticky;
    top: 0;
    z-index: 999;
}
.birch-logo img {
    height: 40px;
    margin-top: 12px;
}
.nav-link {
    color: var(--text-dark) !important;
    font-weight: bold;
    font-size: 13px;
}
.nav-link:hover {
    color: var(--accent-forest) !important;
}
.birch-book-layout {
    display: grid;
    grid-template-columns: 1fr 1.3fr;
    gap: 35px;
    max-width: 1200px;
    margin: 0 auto;
    padding: 40px 15px 100px 15px;
    box-sizing: border-box;
}
.birch-page-left {
    background: var(--win-white);
    border: var(--border-fine);
    padding: 35px;
    border-radius: 4px;
    height: fit-content;
}
.birch-page-right {
    background: var(--win-white);
    border: var(--border-fine);
    padding: 35px;
    border-radius: 4px;
}
.birch-card {
    background: var(--win-white);
    border: var(--border-fine);
    padding: 24px;
    margin-bottom: 20px;
    transition: all 0.25s cubic-bezier(0.25, 0.8, 0.25, 1);
}
.birch-card:hover {
    border-color: var(--accent-forest);
    box-shadow: 0 8px 30px rgba(56, 78, 67, 0.03);
    transform: translateY(-2px);
}
.birch-btn {
    background: transparent;
    color: var(--accent-forest) !important;
    border: 1px solid var(--accent-forest);
    padding: 8px 24px;
    font-weight: bold;
    cursor: pointer;
    display: inline-block;
    transition: all 0.2s;
}
.birch-btn:hover {
    background: var(--accent-forest);
    color: var(--win-white) !important;
}
.sidebar-item {
    display: block;
    color: var(--text-dark);
    padding: 12px 10px;
    border-bottom: 1px dashed rgba(0, 0, 0, 0.05);
    text-decoration: none;
    font-weight: bold;
}
.sidebar-item:hover {
    color: var(--accent-forest);
}
@media (max-width: 992px) {
    .birch-book-layout {
        grid-template-columns: 1fr;
        padding: 20px 15px;
    }
}\n