Top keywords and advertisers

You're given the following table that shows spend by keyword, advertiser, and unique ad ID:

Table: keyword_summary

keyword	ad_id	advertiser_id	total_spend
bicycle	1243213	1234	95
bike	1243213	1234	71
bike tires	1243213	1234	22
bike breaks	1243213	1234	95
bike accessories	1243213	1234	28
...	...	...	...

Using the table above, write a SQL query that returns each keyword along with the advertiser_id of the top spending advertiser, and total spend on the keyword (agnostic of advertiser). Sort the results in descending order by the total spend on the keyword.
You can view/query the data in an interactive SQL fiddle here.