import re

html_doc = ("<section id=\"box3\" class=\"nodisp_zero\" style=\"display: none;\">\n"
	"    <h1 id=\"box_ttl3\" style=\"display: none;\"></h1>\n"
	"    <img style=\"width: 100%; display: none;\" id=\"box_img3\" alt=\"box3\" src=\"https://s...content-available-to-author-only...s.jp/s/topics/img/dummy.png\" class=\"lazy\" data-original=\"https://s...content-available-to-author-only...s.jp/s/topics/img/201808/201808220015_box_img3_A.jpg?1533975785\">\n"
	"    <figcaption id=\"box_caption3\" style=\"display: none;\"></figcaption>\n"
	"    <div class=\"textarea clearfix\">\n"
	"        <h2 id=\"box_subttl3\" style=\"display: none;\"></h2>\n"
	"        <div class=\"fontL\" id=\"box_com3\" style=\"display: none;\"></div>\n"
	"    </div>\n"
	"</section>")

# You can manually specify the number of replacements by changing the 4th argument
html_doc = re.sub(r"display:\s*none;?", "", html_doc, 0)

print(str(html_doc))