Set title line-height in em rather than rem #123

Job	Run time
test-postgres-elasticsearch7 (3.8, Django>=4.1,<4.2, false)	9m 9s
test-postgres (3.8, Django>=3.2,<3.3, false, --parallel)	19m 23s
test-mysql (3.8, Django>=3.2,<3.3, false)	28m 42s
test-postgres (3.11, Django>=4.2,<4.3, postgres:12, notz, false, --parallel)	11m 1s
test-postgres-elasticsearch6 (3.8, Django>=3.2,<3.3)	8m 17s
test-sqlite (3.9, Django>=4.1,<4.2)	14m 29s
test-mysql (3.10, Django>=4.2,<4.3, false, --parallel)	15m 8s
test-postgres (3.10, Django>=4.1,<4.2, false, emailuser, --parallel)	13m 33s
test-postgres (3.10, git+https://github.com/django/django.git@stable/4.2.x#egg=Django, true, post...	18m 35s
test-sqlite-elasticsearch5 (3.8, Django>=3.2,<3.3)	8m 9s
test-postgres (3.10, git+https://github.com/django/django.git@main#egg=Django, true, postgres:12,...	2m 28s
test-sqlite-elasticsearch8 (3.10, Django>=4.2,<4.3, emailuser)	9m 14s
test-sqlite-opensearch2 (3.9, Django>=4.1,<4.2, false)	7m 1s
coverage	1m 36s
	2h 46m 45s

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