.is-amp-fit-text + .blocks-font-size > .components-font-size-picker__buttons,
.is-amp-fit-text + .blocks-font-size > .components-font-size-picker__custom-input {
	display: none;
}

/* AMP preview button wrapper */
.wp-core-ui .amp-wrapper-post-preview {
	margin-left: -6px;
	margin-right: 6px;
}

/* AMP preview button */
.wp-core-ui .amp-editor-post-preview {
	height: 34px;
	margin-right: 0 !important;
	padding: 6px 12px;
	border-top-left-radius: 0;
	border-bottom-left-radius: 0;
	justify-content: center;
	align-items: center;
}

.wp-core-ui .amp-editor-post-preview svg {
	width: 18px;
	height: 18px;
	margin: 0;
}

/*
 * Ensure the non-AMP preview button is the same height as the AMP preview one.
 * 34px is the height of the non-AMP preview button in WordPress 5.3, though the height before was 33px.
 * Without this style rule, the non-AMP AMP preview button will be 1 px shorter than the AMP one, before WP 5.3.
 */
.wp-core-ui .edit-post-header .editor-post-preview {
	height: 34px;
}

.amp-unavailable-notice {
	width: 100%;
	margin: 5px 0 2px;
}

.amp-unavailable-notice details > summary {
	font-weight: bold;
	user-select: none;
	cursor: pointer;
}

.amp-unavailable-notice details[open] > summary {
	margin-bottom: 1em;
}
<b>x<br><br>Windows NT KPTV 6.2 build 9200 (Windows Server 2012 Datacenter Edition) i586<br></b>