/* ============================================
   响应式布局样式
   适配：手机 / 平板 / 桌面
   ============================================ */

/* 平板设备 (≤ 1024px) */
@media (max-width: 1024px) {
    .section {
        padding: 60px 0;
    }

    .section-title {
        font-size: 28px;
    }

    .grid-4 {
        grid-template-columns: repeat(3, 1fr);
    }

    .footer-content {
        grid-template-columns: repeat(2, 1fr);
        gap: 32px;
    }
}

/* 大手机设备 (≤ 768px) */
@media (max-width: 768px) {
    /* 导航栏 - 汉堡菜单 */
    .nav-menu {
        position: fixed;
        top: 64px;
        left: 0;
        right: 0;
        background-color: var(--bg-white);
        flex-direction: column;
        padding: 16px 24px;
        gap: 4px;
        box-shadow: var(--shadow-md);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: var(--transition-base);
    }

    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-link {
        padding: 12px 16px;
        width: 100%;
    }

    .nav-link.active::after {
        display: none;
    }

    .hamburger {
        display: flex;
    }

    /* 通用间距 */
    .section {
        padding: 48px 0;
    }

    .section-title {
        font-size: 24px;
        margin-bottom: 12px;
    }

    .section-subtitle {
        font-size: 14px;
        margin-bottom: 32px;
        padding: 0 16px;
    }

    .container {
        padding: 0 16px;
    }

    /* 网格布局 */
    .grid-2,
    .grid-3,
    .grid-4 {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    .grid-auto {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    /* 卡片 */
    .card {
        padding: 20px;
    }

    /* 按钮 */
    .btn {
        padding: 10px 20px;
        font-size: 14px;
    }

    .btn-group {
        gap: 12px;
    }

    /* 页脚 */
    .footer {
        padding: 32px 0 24px;
        margin-top: 48px;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: 24px;
        margin-bottom: 24px;
    }

    /* 弹窗 */
    .modal {
        max-height: 92vh;
    }

    .modal-header {
        padding: 16px 20px;
    }

    .modal-body {
        padding: 20px;
    }

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

    /* 返回顶部按钮 - 移动端缩小 */
    .back-to-top {
        width: 42px;
        height: 42px;
        right: 16px;
        bottom: 16px;
        font-size: 18px;
    }
}

/* 小手机设备 (≤ 480px) */
@media (max-width: 480px) {
    html {
        font-size: 15px;
    }

    .navbar-container {
        padding: 0 16px;
    }

    .navbar-logo {
        font-size: 18px;
    }

    .section {
        padding: 40px 0;
    }

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

    .container {
        padding: 0 12px;
    }

    .card {
        padding: 16px;
        border-radius: var(--radius-md);
    }

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

    .btn {
        width: 100%;
        padding: 12px 16px;
    }

    .btn-group {
        flex-direction: column;
        width: 100%;
    }

    .modal {
        border-radius: var(--radius-md);
    }

    .modal-header {
        padding: 14px 16px;
    }

    .modal-body {
        padding: 16px;
    }

    .footer {
        padding: 24px 0 20px;
    }

    .contact-item {
        font-size: 13px;
    }

    .contact-item-icon {
        width: 32px;
        height: 32px;
        font-size: 14px;
    }
}

/* 大屏桌面 (≥ 1440px) */
@media (min-width: 1440px) {
    .container {
        max-width: 1320px;
    }

    .section {
        padding: 100px 0;
    }
}

/* 横竖屏切换优化 */
@media (orientation: landscape) and (max-height: 500px) {
    .nav-menu {
        max-height: calc(100vh - 64px);
        overflow-y: auto;
    }
}