Dropdown在滚动容器内，展开后再滚动时标题和面板分离

Description

Contributor guide

Tech stack

typescriptreactcss

Domain

frontendmobile

Issue type

bug

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

3

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

half day

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

fresh

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

ReactCSSBasic understanding of antd mobile

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

65

Research direction

Investigate the Dropdown component's implementation in the antd mobile repository, focusing on the popup/panel positioning logic. Check the CSS for any fixed positioning that doesn't account for scroll containers. Look at the sandbox provided to replicate the issue. Consider whether the component needs to use a portal or adjust its position dynamically on scroll.