What does Isaiah 28:1 mean?

Trouble is coming for the proud leaders of Ephraim, whose glory fades like a dying flower—people drunk with their own importance, sitting at the head of a rich valley, overwhelmed by wine. Isaiah 28:1 - Modern Text Bible

(Isaiah warns the leaders of Israel’s northern kingdom, who are arrogant and self-indulgent, that their pride will lead to their downfall.)