Для примера использую SVG файл логотипа из шапки. Исходный код файла преобразую в конвертере и вставляю в css получившуюся строку backgound: url('строка из конвертера')
Исходный код файла SVG:
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Сконвертированный исходный код в виде свойства background:
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background: 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}
Результат
Конвертер SVG: