Tạo nút lên đầu trang phong cách tên lửa

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<a class='backtop' href='#' title='Lên đầu trang'><img alt='Lên đầu trang' src='https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhEjh-A2p0sUu2z5caRWzl25qfkIFpDhjRIgtO6eDInE2ixuaCq3uT-w1SxaHFaYb70dGfVqs48Ar1KzT7Uj96A2mqgHsigWf3RhtsGnS6Fq6aQM50JE5YVmUYbfLf6MV2-D6GY4IeBzfKz/h120/backtop.webp'/></a>
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