Update dashboard panels' bg in dark theme #169

Job	Run time
test-sqlite (3.11, Django>=5.0,<5.1, 1)	3m 6s
test-mysql (3.10, Django>=4.2,<4.3, false)	4m 35s
test-postgres-elasticsearch7 (3.9, Django>=4.2,<4.3, false)	7m 10s
test-sqlite (3.12, Django>=5.1,<5.2, emailuser, --parallel)	2m 48s
test-mysql (3.11, Django>=4.2,<4.3, false, mariadb:10.5)	4m 34s
test-postgres (3.9, Django>=4.2,<4.3, psycopg2>=2.6, false, --parallel)	2m 15s
test-mysql (3.12, Django>=5.1,<5.2, false, mariadb:11.4, emailuser)	4m 35s
test-postgres (3.12, Django>=5.0,<5.1, psycopg>=3.1.8, postgres:15, notz, false, --parallel)	2m 33s
test-mysql (3.12, Django>=5.1,<5.2, false, --parallel, mysql:8.4, emailuser)	4m 18s
test-sqlite-elasticsearch8 (3.12, Django>=5.1,<5.2, emailuser)	7m 15s
test-postgres (3.11, git+https://github.com/django/django.git@stable/5.1.x#egg=Django, psycopg>=3...	2m 35s
test-sqlite-opensearch2 (3.10, Django>=5.0,<5.1, false)	5m 59s
test-postgres (3.12, git+https://github.com/django/django.git@main#egg=Django, psycopg>=3.1.8, tr...	2m 33s
coverage	0s
	54m 16s

Provide feedback