SoundCloud on AMP Error

After pasting Soundcloud I have an error for the amp page:
The attribute ‘width’ in tag ‘amp-iframe’ is set to the invalid value ‘100%’.
This is an element:
<amp-iframe **width="100%"** height="400" frameborder="1" src=";;show_artwork=true" sandbox="allow-scripts allow-same-origin" layout="responsive" class="i-amphtml-element i-amphtml-error i-amphtml-built"><i-amphtml-scroll-container></i-amphtml-scroll-container></amp-iframe>
My styles doesn’t work because of inline styles. How can I fix this? Or how can I add width for amp by default?
Thank you)

Here is details The AMP Validator
How can I interact or predetermine with width inside amp-iframe?