Method InsertRule

Used to insert a new rule into the media block

public ulong InsertRule(string rule, ulong index)

rule string: The parsable text representing the rule. For rule sets this contains both the selector and the style declaration. For at-rules, this specifies both the at-identifier and the rule content.
index ulong: The index within the media block's rule collection of the rule before which to insert the specified rule. If the specified index is equal to the length of the media blocks's rule collection, the rule will be added to the end of the media block.

ulong: The index within the media block's rule collection of the newly inserted rule.

DomException: HIERARCHY_REQUEST_ERR: Raised if the rule cannot be inserted at the specified index, e.g., if an @import rule is inserted after a standard rule set or other at-rule.
DomException: INDEX_SIZE_ERR: Raised if the specified index is not a valid insertion point.
DomException: NO_MODIFICATION_ALLOWED_ERR: Raised if this media rule is readonly
DomException: SYNTAX_ERR: Raised if the specified rule has a syntax error and is unparsable