页面底部的页脚仅在页面内容较小时有效

Question

使用此html和CSS在php页面底部创建和重用页脚：

footer.php：

==7558== Invalid read of size 8
==7558==    at 0x109049: delete_all_employees (emp.c:300)
==7558==    by 0x108BCB: main (rpt.c:37)
==7558==  Address 0x5232760 is 0 bytes inside a block of size 
40 free'd
==7558==    at 0x4C30D3B: free (in 
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)   
==7558==    by 0x108E15: free_emp (emp.c:175)
==7558==    by 0x109044: delete_all_employees (emp.c:299)
==7558==    by 0x108BCB: main (rpt.c:37)
==7558==  Block was alloc'd at
==7558==    at 0x4C31B25: calloc (in                     
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7558==    by 0x108DAE: new_emp (emp.c:143)
==7558==    by 0x108C73: add_employee (emp.c:65)
==7558==    by 0x108FB9: load_employees (emp.c:272)
==7558==    by 0x108BA2: main (rpt.c:28)

有任何提示吗？