/* 全局样式 */
body {
    font-family: 'Microsoft YaHei', 'PingFang SC', sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f7f6;
    color: #333;
}
.top_pic{
    cursor: pointer;
}

a {
    text-decoration: none;
    color: inherit;
}

/* Header */
header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    padding: 15px 5%;
    transition: background-color 0.3s ease;
}

header.header-scrolled {
    background-color: #fff;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-weight: bold;
    font-size: 24px;
}

.nav-center {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    gap: 40px;
}

.nav-center a {
    font-weight: 500;
    padding: 5px 0;
    border-bottom: 2px solid transparent;
    transition: border-color 0.3s ease;
}

.header-scrolled .nav-center a {
    color: #333;
}

.header-scrolled .nav-center a:hover {
    color: #007bff;
    border-bottom-color: #007bff;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 20px;
}

.nav-right a {
    font-size: 14px;
}

.header-scrolled .nav-right a {
    color: #333;
}

.btn-login {
    background-color: #007bff;
    color: #fff;
    padding: 8px 20px;
    border-radius: 20px;
    transition: background-color 0.3s ease;
}

.btn-login:hover {
    background-color: #0056b3;
}

/* --- Animation Keyframes & Classes --- */

/* Fade in from bottom */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in-up {
    animation: fadeInUp 0.8s ease-out forwards;
}

/* --- End of Animations --- */


/* Hero Section */
.hero {
    background-image: url('icon/01首页2_slices/annotation@2x.png');
    background-size: cover;
    background-position: center;
    height: 60vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: #fff;
}

.hero-content h1 {
    font-size: 48px;
    margin-bottom: 20px;
}

/* Other Sections */
.features {
    padding: 60px 5%;
}

footer {
    text-align: center;
    padding: 20px 5%;
    margin-top: 40px;
    background-color: #333;
    color: #fff;
}