:root {
    --primary: #FF6B35;
    --primary-dark: #E55A2B;
    --text: #1a1a2e;
    --text-light: #666;
    --bg: #ffffff;
    --bg-alt: #f8f9fa;
    --card-bg: #ffffff;
    --border: #e0e0e0;
    --shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
    --sidebar-width: 260px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Microsoft YaHei', 'PingFang SC', sans-serif;
    color: var(--text);
    line-height: 1.6;
    background: var(--bg);
    display: flex;
    height: 100vh;
    overflow: hidden;
}

.sidebar {
    width: var(--sidebar-width);
    height: 100vh;
    background: #1a1a2e;
    color: white;
    overflow-y: auto;
    flex-shrink: 0;
    display: flex;
    flex-direction: column;
}

.sidebar-header {
    padding: 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.logo {
    font-size: 18px;
    font-weight: 700;
    color: var(--primary);
    text-decoration: none;
    display: block;
    padding: 12px 16px;
}

.sidebar-divider {
    height: 1px;
    background: rgba(255, 255, 255, 0.1);
    margin: 0;
}

.board-name {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.6);
    font-weight: 500;
    padding: 0 16px;
    display: flex;
    align-items: center;
    height: 40px;
}

.section-selector {
    width: 100%;
    padding: 8px 12px;
    background: rgba(255, 255, 255, 0.1);
    color: white;
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 6px;
    font-size: 14px;
    cursor: pointer;
}

.section-selector:hover {
    background: rgba(255, 255, 255, 0.15);
}

.section-selector option {
    background: #1a1a2e;
    color: white;
}

.sidebar-nav {
    padding: 12px 0;
    flex: 1;
}

.nav-section {
    margin-bottom: 2px;
}

.nav-link {
    display: block;
    padding: 10px 20px;
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
}

.nav-link:hover {
    background: rgba(255, 255, 255, 0.1);
    color: white;
}

.nav-group {
    font-weight: 600;
    position: relative;
}

.nav-group::after {
    content: '+';
    position: absolute;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
}

.nav-group.expanded::after {
    content: '-';
}

.sub-nav {
    display: none;
    background: rgba(0, 0, 0, 0.2);
}

.sub-nav.open {
    display: block;
}

.sub-nav .nav-link {
    padding-left: 36px;
    font-size: 12px;
    font-weight: 400;
}

.sub-nav-2 {
    background: rgba(0, 0, 0, 0.15);
}

.sub-nav-2 .nav-link {
    padding-left: 52px;
    font-size: 11px;
    font-weight: 400;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.sub-nav-2 .nav-link:last-child {
    border-bottom: none;
}

.sub-nav .nav-group {
    font-weight: 500;
}

.main-content {
    flex: 1;
    height: 100vh;
    overflow: hidden;
}

#content-frame {
    width: 100%;
    height: 100%;
    border: none;
}

@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        left: -100%;
        z-index: 1000;
    }
}