html, body {
    height: 100%;
    margin: 0;
    padding: 0;
    font-family: "Microsoft YaHei", "PingFang SC", Arial, sans-serif;
    background-color: #f5f7fa;
}

.app-container {
    display: flex;
    flex-direction: column;
    height: 100vh;
    overflow: hidden;
}

/* ---------- 固定头部 ---------- */
.app-header {
    flex-shrink: 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    /* 不再整体渐变，分两部分 */
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

/* ----- 上半部分：白色背景，品牌左对齐 ----- */
.header-brand-row {
    background-color: #ffffff;
    padding: 8px 20px;
    border-bottom: 1px solid #e0e6ed;
}

.brand {
    display: flex;
    align-items: center;
    gap: 16px;
    max-width: 100%;
    margin: 0 auto;
}

.brand-logo {
    height: 60px;
    width: auto;
}

.brand-text {
    display: flex;
    flex-direction: column;
    line-height: 1.3;
}

.brand-title {
    font-size: 20px;
    font-weight: 700;
    letter-spacing: 2px;
    /* 使用蓝色渐变底色作为文字颜色 */
    color: #1a3a5c; /* 与渐变起始色一致 */
}

.brand-sub {
    font-size: 14px;
    letter-spacing: 3px;
    color: #2a5f7a; /* 渐变色中的较亮色 */
    font-weight: 300;
    margin-top: 1px;
}

/* ----- 下半部分：蓝色渐变背景，导航居中 ----- */
.header-nav-row {
    background: linear-gradient(135deg, #1a3a5c 0%, #2a5f7a 100%);
    padding: 8px 20px;
}

.main-nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 2.2em;
    max-width: 100%;
    margin: 0 auto;
}

    .main-nav .nav-link {
        font-size: 18px !important;
        font-weight: 600 !important;
        color: #ffffff !important;
        text-decoration: none !important;
        letter-spacing: 1px;
        padding: 4px 2px;
        border-bottom: 3px solid transparent;
        transition: opacity 0.25s ease, border-color 0.25s ease;
        white-space: nowrap;
    }

        .main-nav .nav-link:hover {
            opacity: 0.8;
            text-decoration: none !important;
        }

        .main-nav .nav-link.active {
            border-bottom-color: #ffffff;
            font-weight: 700 !important;
            opacity: 1;
        }

/* ---------- 可滚动内容区 ---------- */
.app-main {
    flex: 1;
    overflow-y: auto;
    padding: 0;
    background-color: #ffffff;
}

    .app-main > * {
        max-width: 100%;
        margin: 0 auto;
        padding: 32px 32px 40px;
    }

/* ---------- 固定底部 ---------- */
.app-footer {
    flex-shrink: 0;
    position: sticky;
    bottom: 0;
    z-index: 1000;
    background: linear-gradient(135deg, #1a3a5c 0%, #2a5f7a 100%);
    color: rgba(255, 255, 255, 0.85);
    padding: 0 32px;
    box-shadow: 0 -2px 12px rgba(0, 0, 0, 0.15);
}

.footer-inner {
    max-width: 1280px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: center;
    height: 56px;
    font-size: 18px;
    letter-spacing: 0.5px;
    gap: 12px;
}

.footer-divider {
    color: rgba(255, 255, 255, 0.25);
}

/* ---------- 响应式适配 ---------- */
@media (max-width: 768px) {
    .brand-logo {
        height: 36px;
    }

    .brand-title {
        font-size: 22px;
    }

    .brand-sub {
        font-size: 12px;
    }

    .main-nav .nav-link {
        font-size: 16px !important;
    }

    .main-nav {
        gap: 1.2em;
    }

    .app-main > * {
        padding: 20px 16px 30px;
    }

    .footer-inner {
        font-size: 16px;
        height: 48px;
    }
}

@media (max-width: 480px) {
    .brand {
        flex-direction: column;
        align-items: flex-start; /* 左对齐 */
        gap: 4px;
    }

    .brand-text {
        text-align: left;
    }

    .brand-title {
        font-size: 18px;
    }

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

    .brand-logo {
        height: 30px;
    }

    .main-nav .nav-link {
        font-size: 14px !important;
        padding: 4px 2px;
    }

    .main-nav {
        gap: 0.8em;
    }

    .footer-inner {
        font-size: 14px;
        height: 44px;
    }
}