/* ============================================================
   京电科技企业官网 - 共享样式表
   适用: 全部页面 (index.html / about.html / products.html /
         product-detail.html / case-detail.html / patents.html)
   ============================================================ */

/* ========== CSS 变量 ========== */
:root {
    --primary: #1a56db;
    --primary-dark: #1344b0;
    --accent: #06b6d4;
    --bg-white: #ffffff;
    --bg-light: #f8fafc;
    --text-dark: #1e293b;
    --text-gray: #64748b;
    --text-light: #94a3b8;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.12);
    --radius: 12px;
    --radius-sm: 8px;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --max-width: 1200px;
    --nav-height: 72px;
}

/* ========== 全局重置 ========== */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: var(--nav-height);
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
                 "Microsoft YaHei", "Noto Sans SC", sans-serif;
    color: var(--text-dark);
    background: var(--bg-white);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ========== 通用容器 ========== */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
}

/* ========== 返回链接 ========== */
.back-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    margin-bottom: 24px;
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.95rem;
    transition: color var(--transition), gap var(--transition);
}
.back-link:hover {
    text-decoration: underline;
    gap: 10px;
}

/* ========== 按钮体系 ========== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 32px;
    border-radius: 30px;
    font-weight: 600;
    font-size: 1rem;
    text-decoration: none;
    border: none;
    cursor: pointer;
    transition: transform var(--transition), box-shadow var(--transition),
                background var(--transition), color var(--transition);
    line-height: 1.4;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: #fff;
    box-shadow: 0 4px 16px rgba(26, 86, 219, 0.3);
}
.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 28px rgba(26, 86, 219, 0.4);
}
.btn-primary:active {
    transform: translateY(-1px);
}

.btn-outline {
    background: transparent;
    color: var(--primary);
    border: 2px solid var(--primary);
}
.btn-outline:hover {
    background: var(--primary);
    color: #fff;
    transform: translateY(-3px);
}

.btn-detail {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 8px 20px;
    border-radius: 20px;
    background: rgba(26, 86, 219, 0.08);
    color: var(--primary);
    text-decoration: none;
    font-size: 0.85rem;
    font-weight: 600;
    transition: background var(--transition), color var(--transition),
                transform var(--transition);
}
.btn-detail:hover {
    background: var(--primary);
    color: #fff;
    transform: translateX(3px);
}

/* ========== 通用状态 ========== */
.loading,
.empty {
    text-align: center;
    padding: 40px;
    color: var(--text-gray);
}

/* ========== 通用图片画廊（详情页共用） ========== */
.gallery-grid-common {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 16px;
    margin-bottom: 30px;
}
.gallery-grid-common img {
    width: 100%;
    height: 220px;
    object-fit: cover;
    border-radius: var(--radius);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease;
}
.gallery-grid-common img:hover {
    transform: scale(1.02);
}

/* ========== 内容卡片（详情页共用） ========== */
.content-card {
    background: #fff;
    padding: 32px;
    border-radius: var(--radius);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
    border: 1px solid #f1f5f9;
}
.content-card p {
    margin-bottom: 16px;
    line-height: 1.9;
}
.content-card p:last-child {
    margin-bottom: 0;
}

/* ========== 响应式图片默认行为 ========== */
img {
    max-width: 100%;
    height: auto;
}

/* ========== 通用动画 ========== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(24px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}