/* ============================================================
   common.css — 公共样式（头部、底部、全局变量、重置）
   上海昶巽机械设备有限公司
   ============================================================ */

/* ── 全局 CSS 变量 ─────────────────────────────────────────── */
:root {
    --color-primary:    #030213;
    --color-dark:       #0a0a0a;
    --color-muted:      #717182;
    --color-white:      #ffffff;
    --color-bg-light:   rgba(236, 236, 240, 0.3);
    --color-border:     rgba(0, 0, 0, 0.1);

    --font-family: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', -apple-system,
                   BlinkMacSystemFont, 'Segoe UI', sans-serif;

    --container-max:     1280px;
    --container-pad:     32px;
    --header-height:     64px;
    --radius:            14px;
    --radius-sm:         8px;
    --transition:        0.3s ease;
    --shadow-card:       0 1px 3px rgba(0,0,0,.08), 0 4px 16px rgba(0,0,0,.06);
    --shadow-card-hover: 0 8px 32px rgba(0,0,0,.12);
}

/* ── CSS 重置 ────────────────────────────────────────────── */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-family);
    color: var(--color-dark);
    background: var(--color-white);
    line-height: 1.6;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color var(--transition);
}

ul, ol {
    list-style: none;
}

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
    outline: none;
}

/* ── 容器 ────────────────────────────────────────────────── */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-pad);
    width: 100%;
}

/* ── 头部 / 导航 ──────────────────────────────────────────── */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 999;
    height: var(--header-height);
    background: rgba(255, 255, 255, 0.95);
    border-bottom: 1px solid var(--color-border);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    transition: box-shadow var(--transition);
}

.header.scrolled {
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

/* Logo */
.logo a {
    font-size: 20px;
    font-weight: 400;
    color: var(--color-primary);
    white-space: nowrap;
    letter-spacing: 0;
}

/* 桌面导航 */
.nav {
    display: flex;
    align-items: center;
    gap: 32px;
}

.nav-link {
    font-size: 16px;
    font-weight: 400;
    color: var(--color-dark);
    white-space: nowrap;
    position: relative;
    padding-bottom: 2px;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--color-primary);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--transition);
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-primary);
}

.nav-link:hover::after,
.nav-link.active::after {
    transform: scaleX(1);
}

/* 移动端汉堡菜单按钮 */
.menu-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    padding: 6px;
    border-radius: 4px;
    transition: background var(--transition);
}

.menu-toggle:hover {
    background: rgba(0,0,0,0.04);
}

.menu-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--color-primary);
    border-radius: 2px;
    transition: transform var(--transition), opacity var(--transition);
}

.menu-toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.menu-toggle.open span:nth-child(2) { opacity: 0; transform: scaleX(0); }
.menu-toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ── 底部 ────────────────────────────────────────────────── */
.footer {
    background: var(--color-primary);
    color: var(--color-white);
    padding-top: 48px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 40px;
    padding-bottom: 32px;
}

.footer-col-about p {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.8);
    line-height: 1.7;
    margin-top: 8px;
}

.footer-heading {
    font-size: 16px;
    font-weight: 500;
    color: var(--color-white);
    margin-bottom: 16px;
}

.footer-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.footer-list a {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.8);
}

.footer-list a:hover {
    color: var(--color-white);
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.2);
    padding: 24px 0;
    text-align: center;
}

.footer-bottom p {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.6);
}

/* ── 滚动显示动画（公共） ─────────────────────────────────── */
.reveal {
    opacity: 0;
    transform: translateY(28px);
    transition: opacity 0.65s ease, transform 0.65s ease;
}
.reveal.visible {
    opacity: 1;
    transform: translateY(0);
}
.reveal-delay-1 { transition-delay: 0.1s; }
.reveal-delay-2 { transition-delay: 0.2s; }
.reveal-delay-3 { transition-delay: 0.3s; }
.reveal-delay-4 { transition-delay: 0.4s; }

/* ── 响应式：平板 ─────────────────────────────────────────── */
@media (max-width: 1024px) {
    :root {
        --container-pad: 24px;
    }
}

/* ── 响应式：移动端 ───────────────────────────────────────── */
@media (max-width: 768px) {
    :root {
        --container-pad: 16px;
    }

    /* 移动端导航下拉 */
    .nav {
        position: fixed;
        top: var(--header-height);
        left: 0;
        right: 0;
        background: rgba(255, 255, 255, 0.98);
        flex-direction: column;
        align-items: flex-start;
        gap: 0;
        padding: 8px 0 16px;
        border-bottom: 1px solid var(--color-border);
        box-shadow: 0 8px 24px rgba(0,0,0,0.08);
        transform: translateY(-110%);
        opacity: 0;
        visibility: hidden;
        transition: transform 0.35s cubic-bezier(.4,0,.2,1),
                    opacity 0.35s ease,
                    visibility 0.35s ease;
        z-index: 998;
    }

    .nav.open {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-link {
        display: block;
        width: 100%;
        padding: 14px var(--container-pad);
        font-size: 16px;
        border-bottom: 1px solid rgba(0,0,0,0.05);
    }

    .nav-link::after { display: none; }
    .nav-link:last-child { border-bottom: none; }

    .menu-toggle {
        display: flex;
    }

    /* 底部响应式 */
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 28px;
        padding-bottom: 24px;
    }
}