我使用了材质UI textField标签，我想移除文本字段的标签，但当我移除甚至设置为null时，标签不起作用，并且我错过了顶部边框

<Box
            component="form"
            sx={{
              "& .MuiTextField-root": {
                m: 0.2,
                width: "100%",
                marginBottom: "30px",
              },
            }}
            noValidate
            autoComplete="off"
          >
            <div>
              <div className="pass-box">
                <label>username</label>
              </div>
              <TextField
                fullWidth
                placeholder="username
                label=""
                id="outlined-size-small-1"
                size="small"
                value={username}
                onChange={(e) =>          setUsername(e.target.value)}
                InputProps={{
                  endAdornment: (
                    <IconButton className="log-icon">
                      <AccountCircleIcon />
                    </IconButton>
                  ),
                }}
              ></TextField>
              <br />
              <TextField
                fullWidth
                placeholder="password
                label=""
                type="password"
                id="outlined-size-small"
                size="small"
                onChange={(e) => setPassword(e.target.value)}
                InputProps={{
                  endAdornment: (
                    <IconButton className="log-icon">
                      <LockIcon />
                    </IconButton>
                  ),
                }}
              ></TextField>
              <br />
            </div>
          </Box>

这是我的文本字段的图像，您可以看到顶部边框缺失