<li class="nav-item active dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Dropdown link
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
<a class="dropdown-item" href="#">Action</a>
<a class="dropdown-item" href="#">Another action</a>
<a class="dropdown-item" href="#">Something else here</a>
</div>
</li>
我编写了这段代码来使用引导程序创建一个下拉菜单（非常简单），现在我尝试在将鼠标悬停在下拉列表内的项目上时删除背景，但不知何故它们始终保持白色。
这是CSS
.dropdown-menu{
background-color: transparent;
border: transparent;
border: none;
}
.dropdown-menu .dropdown-item > li > a:hover {
background-image: none;
background-color: #000;
}
class Team(db.Model):
__tablename__ = "Teams"
id = db.Column(db.Integer, primary_key=True)
flashscore_id = db.Column(db.String(255), nullable=False, unique=True)
name = db.Column(db.String(255), nullable=False)
leagues = db.relationship("League",
secondary=league_teams_table)
standings = db.relationship('Standing', backref='teams', cascade="all,delete")
fixtures = db.relationship('Fixture', backref='teams', cascade="all,delete")
related_fixtures_table = db.Table('RelatedFixtures',
db.Column('fixture_id', db.Integer, db.ForeignKey('Fixtures.id')),
db.Column('related_fixture_id', db.Integer, db.ForeignKey('Fixtures.id')))
class Fixture(db.Model):
__tablename__ = "Fixtures"
id = db.Column(db.Integer, primary_key=True)
home_id = db.Column(db.Integer, db.ForeignKey('Teams.id'),
nullable=False)
away_id = db.Column(db.Integer, db.ForeignKey('Teams.id'),
nullable=False)
home_ref = db.relationship("Teams", backref="fixture", uselist=False, foreign_keys=[home_id])
away_ref = db.relationship("Teams", backref="fixture", uselist=False, foreign_keys=[away_id])
flashscore_id = db.Column(db.String(255), nullable=False, unique=True)
total_goals = db.Column(db.Integer, …我写了以下代码：
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Mockup TOPdesk</title>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bulma/0.7.1/css/bulma.css" />
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.3.1/css/all.css" integrity="sha384-mzrmE5qonljUremFsqc01SB46JvROS7bZs3IO2EmfFsd15uHvIt+Y8vEf7N7fWAU" crossorigin="anonymous">
<link rel="stylesheet" href="css/style.css" />
<link href="https://fonts.googleapis.com/css?family=Open+Sans:300,400,700" rel="stylesheet">
<script src="https://code.jquery.com/jquery-3.3.1.slim.js" integrity="sha256-fNXJFIlca05BIO2Y5zh1xrShK3ME+/lYZ0j+ChxX2DA=" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/bulma-steps@2.2.1/dist/js/bulma-steps.js"></script>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bulma-steps@2.2.1/dist/css/bulma-steps.min.css">
</head>
<body>
<nav class="navbar is-white">
<div class="container">
<div class="navbar-brand">
<a class="navbar-item brand-text" href="/">
TOPdesk Admin
</a>
<div class="navbar-burger burger" data-target="navMenu">
<span></span>
<span></span>
<span></span>
</div>
</div>
<div id="navMenu" class="navbar-menu">
<div class="navbar-start">
<a class="navbar-item" href="admin.html">
Home
</a>
</div>
</div>
</div>
</nav>
<div class="container">
<div class="columns">
<div class="column is-2"> …我试图一次又一次地使用sum函数，但始终收到错误消息。我写了以下代码：
averages["averages_home_goals"] = sum(d['home_goals'] for d in averages.values() if d)
averages["averages_away_goals"] = sum(d['away_goals'] for d in averages.values() if d)
averages["averages_home_conceded"] = sum(d['home_conceded'] for d in averages.values() if d)
averages["averages_away_conceded"] = sum(d['away_conceded'] for d in averages.values() if d)
print(averages)
averages变量如下所示：
{
'Belconnen%20United': {
'home_goals': 4.0,
'away_goals': 1.0,
'home_conceded': 0.0,
'away_conceded': 2.1666666666666665,
},
'Canberra%20FC': {
'home_goals': 1.75,
'away_goals': 1.8,
'home_conceded': 2.0,
'away_conceded': 2.0,
},
# More data of a similar structure
}
运行此命令时，出现以下错误：
TypeError: 'float' object is not subscriptable
奇怪的是；当我只运行这4行中的一行时，代码可以正常执行（无论哪一行都行）。执行averages["averages_away_goals"] = …