HOUSTON — Daikin Park’s closed roof Friday amplified an already booming crowd of close to 40,000. Fireworks popped with every Astros home run, and the train above the left-field wall moved along the tracks.

“This was a really good regular-season environment,” manager Craig Counsell said after the Cubs’ 7-4 loss Friday. “The fans do a great job. This place is loud always. I just told [rookie starter Cade Horton] that this is a good example of what the playoffs are going to look like. Turn it up a couple of notches. But of a road game that we’ve played this year, this is probably the best example that Cade’s had of what it turns into against a tough lineup.”

Horton allowed a career-high seven runs, including two three-run home runs, in four innings. Before Friday, he’d never surrendered more than four earned runs in a major-league outing.

“I thought we had a good game plan going into it,” Horton said. “Just never really caught my footing.”

Hard contact in the first inning and three walks before he had gotten through the second were early signs of trouble. But Horton got out of both jams.

Right fielder Kyle Tucker, in his first game back in Houston since the Cubs acquired him from the Astros this offseason, threw out Isaac Paredes, who was trying to score from second on a single, for the last out of the first inning.

In the second inning, Horton escaped with the bases loaded by getting Paredes to line out.

Horton, however, wasn’t so fortunate facing the Astros’ lineup a second and third time.

He loaded the bases in the third inning with two walks and a bloop single. Then Horton gave up a sacrifice fly to Victor Caratini and a first-pitch home run to Yanier Diaz. The Astros took a 4-0 lead.

The next inning, back-to-back singles put Horton in another high-leverage situation. And he gave up another first-pitch homer, this time to rookie Cam Smith.

“It was the first time I felt like I wasn’t able to slow the game down,” said Horton, whose ERA went from 3.73 to 4.80. “And I let my emotions get the best of me today. Just got to learn from it and move on. . . . That experience right there will help me be better in October. I’d rather get my [butt] kicked tonight than go out in October and get my [butt] kicked there.”

Smith’s revenge

Smith’s three-run blast landed on the train tracks high above the left-field wall. And it happened to come off one of the handful of players he said he’d gotten to know in his short time in the Cubs’ organization.

The Cubs drafted Smith No. 14 overall out of Florida State last June. After the Cubs traded him to the Astros as part of the deal for Tucker, Smith made Houston’s Opening Day roster.

“It’s opened a lot of doors for me,” Smith said before going 2-for-2 with two walks. “I’ve met a lot of new people, made plenty of friends here, and I get to live out my dream every single day.”

Hoerner, Shaw heating up

In the fifth inning, Cubs second baseman Nico Hoerner hit a solo shot for his second home run in four games after going homerless in his first 74 games of the season.

Rookie Matt Shaw drove in the rest of the Cubs’ runs on doubles in the seventh and ninth innings.