Why the model can only train on size of [64, 64]?

[ohhh-yang]

When I try a size not equal to [64, 64], it comes below fault:
File "/home/PyTorch-VAE/models/vanilla_vae.py", line 122, in forward
mu, log_var = self.encode(input)
File "/home/PyTorch-VAE/models/vanilla_vae.py", line 91, in encode
mu = self.fc_mu(result)
File "/home/anaconda3/envs/py38/lib/python3.8/site-packages/torch/nn/modules/module.py", line 889, in _call_impl
result = self.forward(*input, **kwargs)
File "/home/anaconda3/envs/py38/lib/python3.8/site-packages/torch/nn/modules/linear.py", line 94, in forward
return F.linear(input, self.weight, self.bias)
File "/home/anaconda3/envs/py38/lib/python3.8/site-packages/torch/nn/functional.py", line 1753, in linear
return torch._C._nn.linear(input, weight, bias)
RuntimeError: mat1 dim 1 must match mat2 dim 0