/*首页*/
:root {
	--primary-color: #e74c3c;
	--secondary-color: #c0392b;
}
.btn-primary {
	background-color: var(--primary-color);
	border-color: var(--primary-color);
}
.btn-primary:hover {
	background-color: var(--secondary-color);
	border-color: var(--secondary-color);
}

.hero-section {
	background: linear-gradient(rgba(0,0,0,0.7), rgba(0,0,0,0.7)), url('https://images.unsplash.com/photo-1569718212165-3a8278d5f624?ixlib=rb-1.2.1&auto=format&fit=crop&w=1350&q=80');
	background-size: cover;
	background-position: center;
	color: white;
	padding: 100px 0;
}
.section-title {
	position: relative;
	margin-bottom: 30px;
	padding-bottom: 15px;
}
.section-title::after {
	content: '';
	position: absolute;
	bottom: 0;
	left: 50%;
	transform: translateX(-50%);
	width: 80px;
	height: 3px;
	background-color: var(--primary-color);
}
.brand-card {
	transition: transform 0.3s;
	margin-bottom: 30px;
}
.brand-card:hover {
	transform: translateY(-10px);
}
.news-card {
	margin-bottom: 20px;
}
/* 默认样式（窄屏时有背景色） */
#topnavbarNav {
	background-color: #545454; /* 窄屏下拉背景色 */
	box-shadow: 0 5px 15px rgba(0,0,0,0.1);
	z-index: 5;
}
#topnavbarNav ul{
	text-align:center;
	padding:10px;
	
}

/* 图片容器样式 */
.image-container {
	position: relative;
	height: 50%;
	overflow: hidden;
}

/* 默认主图样式 */
.main-img {
	position: absolute;
	top: 0;
	left: 0;
	width: 100%;
	height: 100%;
	object-fit: cover;
	opacity: 1;
	visibility: visible;
	transition: opacity 0.3s ease, visibility 0.3s ease;
}

/* 悬停图片样式 */
.hover-img {
	width: 80%;
	height: 80%;
	object-fit: cover;
	opacity: 0;
	transition: opacity 0.3s ease, visibility 0.3s ease;
	margin: 0 auto;
	display: block;
	margin-top: 10%;
}

/* 悬停时切换图片 */
.brand-card:hover .main-img {
	opacity: 0;
	visibility: hidden;
}

.brand-card:hover .hover-img {
	opacity: 1;
	visibility: visible;
}


/* 宽屏时强制透明背景 */
@media (min-width: 992px) {
	#topnavbarNav {
		background-color: transparent !important;
		box-shadow: none !important;
		
	}
	
}