/* ============ 授课白板样式 ============ */
.whiteboard-wrapper {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.whiteboard-toolbar {
    display: flex;
    align-items: center;
    gap: 10px;
    flex-wrap: wrap;
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 10px 14px;
}

.whiteboard-toolbar .tool-group {
    display: flex;
    align-items: center;
    gap: 6px;
}

.whiteboard-toolbar .divider {
    width: 1px;
    height: 24px;
    background: var(--border);
    margin: 0 4px;
}

.wb-tool {
    min-width: 40px;
    padding: 6px 12px;
    border: 1px solid var(--border);
    background: #fff;
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
    transition: all .15s;
}
.wb-tool:hover { border-color: var(--primary); color: var(--primary); }
.wb-tool.active {
    background: var(--primary);
    color: #fff;
    border-color: var(--primary);
}

.wb-color {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    border: 2px solid transparent;
    cursor: pointer;
    padding: 0;
}
.wb-color.active { border-color: #1f2937; box-shadow: 0 0 0 2px #fff inset; }

.wb-color-picker {
    width: 36px;
    height: 32px;
    border: 1px solid var(--border);
    border-radius: 6px;
    cursor: pointer;
    padding: 2px;
}

.wb-size {
    padding: 5px 8px;
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 14px;
}

.whiteboard-canvas-wrap {
    position: relative;
    background: #fff;
    border: 1px solid var(--border);
    border-radius: 8px;
    overflow: hidden;
    touch-action: none;
}
.whiteboard-canvas-wrap canvas {
    display: block;
    width: 100%;
    height: 100%;
    cursor: crosshair;
}

.whiteboard-status {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    color: var(--text-sub);
}
.wb-status-dot {
    width: 9px;
    height: 9px;
    border-radius: 50%;
    background: var(--danger);
}
.wb-status-dot.connected { background: var(--success); }

.wb-room-title {
    font-size: 15px;
    font-weight: 600;
    color: var(--text-main);
}

/* 多页白板翻页栏 */
.whiteboard-pager {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    padding: 10px 14px;
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
}
.whiteboard-pager .wb-page-indicator {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-main);
    min-width: 100px;
    text-align: center;
}

/* 房间选择列表 */
.room-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 16px;
}
.room-card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 20px;
}
.room-card h3 { margin: 0 0 8px; font-size: 17px; }
.room-card .cat { color: var(--primary); font-size: 13px; }