/* 外层舞台与聊天 iframe 共用：页面固定，内容区保留独立滚动。 */
html {
    width: 100%;
    height: 100%;
    overflow: hidden;
    overscroll-behavior: none;
    -webkit-text-size-adjust: 100%;
    text-size-adjust: 100%;
    touch-action: pan-x pan-y;
}

body {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    height: 100dvh;
    height: var(--app-height, 100dvh);
    box-sizing: border-box;
    overflow: hidden;
    overscroll-behavior: none;
    touch-action: pan-x pan-y;
}

#screen2 { max-width: 100%; }

.dialogue-scroll {
    overflow-x: hidden;
    overscroll-behavior-y: contain;
    overflow-wrap: anywhere;
}

@media (max-width: 991px) {
    .workspace-layout, .stage-column, .learning-board,
    .teacher-dropdown-wrap, #textform, #text {
        min-width: 0;
    }

    /* 避免 iPhone 聚焦小字号输入框时自动放大。 */
    #text { font-size: 16px; }

    .teacher-dropdown-menu {
        min-width: 0;
        width: min(280px, calc(100vw - 64px));
        max-height: 60dvh;
        overflow-y: auto;
        overscroll-behavior: contain;
    }
}