Attendance Modal - Copy this React, Tailwind Component to your project

Design a responsive, modern modal titled 'Generate Attendance Sheet' with Material Design. Include: a title, close button, '+ Add Shift/Class' buttons showing selected names, a pre-filled 'Month and Year' picker, and a blue 'Download Report' button with loading spinner. Use a dark theme, smooth animations, and a responsive layout. Ensure accessibility with ARIA labels and keyboard support.