/* ===== 顶部导航栏 - 浅色调 ===== */
.top-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 999;
    background: #ffffff;
    box-shadow: 0 2px 8px rgba(0,0,0,0.08);
    border-bottom: 1px solid #e8e8e8;
    display: flex;
    justify-content: center;
    padding: 0 20px;
}

.top-nav-inner {
    max-width: 800px;
    width: 100%;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 8px;
    color: #2c3e50;
    font-size: 20px;
    font-weight: 700;
    text-decoration: none;
    letter-spacing: 1px;
    flex-shrink: 0;
}

.nav-brand .brand-icon {
    font-size: 24px;
}

.nav-brand .brand-sub {
    font-size: 12px;
    font-weight: 400;
    color: #999;
    margin-left: 4px;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 4px;
    flex-wrap: wrap;
    justify-content: flex-end;
}

.nav-links a {
    color: #555;
    text-decoration: none;
    padding: 8px 14px;
    border-radius: 6px;
    font-size: 14px;
    font-weight: 500;
    transition: all 0.25s ease;
    position: relative;
    white-space: nowrap;
}

.nav-links a:hover {
    background: #f0f4ff;
    color: #007BFF;
}

.nav-links a.active {
    background: #e8f0fe;
    color: #007BFF;
    font-weight: 600;
}

.nav-links a .nav-badge {
    display: inline-block;
    background: #ff6b6b;
    color: #fff;
    font-size: 10px;
    padding: 1px 7px;
    border-radius: 10px;
    margin-left: 4px;
    vertical-align: top;
    font-weight: 600;
}

/* 汉堡菜单按钮 */
.nav-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    background: none;
    border: none;
    padding: 6px 4px;
    margin: 0;
}

.nav-toggle span {
    display: block;
    width: 18px;
    height: 2px;
    background: #555;
    border-radius: 3px;
    transition: all 0.3s ease;
    margin: 0 auto;
}

.nav-toggle span + span {
    margin-top: 4px;
}

/* ===== 导航栏响应式 ===== */
@media screen and (max-width: 480px) {
    body {
        padding-top: 60px;
    }

    .top-nav-inner {
        height: 56px;
    }

    .nav-brand {
        font-size: 17px;
    }
    .nav-brand .brand-sub {
        font-size: 10px;
    }

    .nav-toggle {
        display: flex;
    }

    .nav-links {
        position: absolute;
        top: 56px;
        left: 0;
        right: 0;
        background: #ffffff;
        flex-direction: column;
        padding: 12px 16px 18px;
        gap: 2px;
        display: none;
        box-shadow: 0 8px 20px rgba(0,0,0,0.15);
        border-top: 1px solid #eee;
    }

    .nav-links.open {
        display: flex;
    }

    .nav-links a {
        width: 80%;
        text-align: center;
        padding: 10px 12px;
        font-size: 15px;
        border-radius: 8px;
    }

    .nav-links a:hover {
        background: #f0f4ff;
    }
}

@media screen and (max-width: 360px) {
    .nav-brand {
        font-size: 15px;
    }
}

@media screen and (min-width: 481px) {
    .nav-toggle {
        display: none !important;
    }
    .nav-links {
        display: flex !important;
    }
}