:root {
    --bg-body: #0D0D0D;
    --text-main: #8C8C8C;
    --text-title: #FFFFFF;
    --nav-bg: rgba(18, 18, 18, 0.85);
    --nav-border: #1F1F1F;
    --grid-color: rgba(255, 255, 255, 0.01);
    --btn-bg: #1A1A1A;
    --btn-border: #2A2A2A;
    --btn-text: #8A8A8A;
    --accent-color: #00E5FF;
    
    --slide-hw-bg: #0D0D0D;
    --slide-circuit-bg: #0A0F12;
    --slide-pcb-bg: #120E0A;
    --slide-structure-bg: #0A1211;
    --slide-web-bg: #0E0A12;
    --slide-border: #1A1A1A;
    /* 深色模式下的滤镜：85% 到 95% 浓度的碳黑遮罩 */
    --image-overlay-start: rgba(13, 13, 13, 0.40); /* 顶部/左侧较淡，显露图片 */
    --image-overlay-end: rgba(13, 13, 13, 0.70);   /* 底部/右侧稍浓，压制高光 */
    /* 最下方输入框样式 */
    --input-bg: #161616;
    --input-border: #252525;
    --input-focus: #00E5FF;
}

body.light-theme {
    --bg-body: #F4F4F6;
    --text-main: #4A4A4A;
    --text-title: #111111;
    --nav-bg: rgba(255, 255, 255, 0.9);
    --nav-border: #E5E5E7;
    --grid-color: rgba(0, 0, 0, 0.025);
    --btn-bg: #EEEEF2;
    --btn-border: #D1D1D6;
    --btn-text: #555555;
    --accent-color: #FF6B00;

    --slide-hw-bg: #F4F4F6;
    --slide-circuit-bg: #EAF1F5;
    --slide-pcb-bg: #F5EFEA;
    --slide-structure-bg: #EAEFEF;
    --slide-web-bg: #EFEAF5;
    --slide-border: #E5E5E7;
    /* 浅色模式下的滤镜：85% 到 95% 浓度的工业灰白遮罩 */
    --image-overlay-start: rgba(244, 244, 246, 0.40);
    --image-overlay-end: rgba(244, 244, 246, 0.70);
    /* 最下方输入框样式 */
    --input-bg: #FFFFFF;
    --input-border: #D1D1D6;
    --input-focus: #FF6B00;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
}

body {
    background-color: var(--bg-body);
    color: var(--text-main);
    overflow: hidden;
    display: flex;
    height: 100vh;
    transition: background-color 0.4s ease, color 0.4s ease;
}

/* PC 固定侧边栏 */
.pc-nav {
    width: 280px;
    background-color: var(--nav-bg);
    backdrop-filter: blur(20px);
    border-right: 1px solid var(--nav-border);
    position: fixed;
    top: 0;
    bottom: 0;
    left: 0;
    padding: 50px 32px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    z-index: 100;
    transition: background-color 0.4s, border-color 0.4s;
}

.pc-nav .logo {
    font-size: 1.2rem;
    font-weight: 900;
    letter-spacing: 3px;
    color: var(--text-title);
}

.nav-links {
    list-style: none;
}

.nav-links li {
    margin: 32px 0;
}

.nav-links a {
    color: var(--text-main);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 600;
    letter-spacing: 1px;
    transition: color 0.3s;
}

.nav-links a:hover {
    color: var(--accent-color);
}

.control-panel {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.theme-switcher button {
    width: 100%;
    padding: 10px 14px;
    background-color: var(--btn-bg);
    border: 1px solid var(--btn-border);
    color: var(--btn-text);
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 1px;
    cursor: pointer;
    text-align: left;
    transition: all 0.3s ease;
}

.theme-switcher button:hover {
    border-color: var(--accent-color);
    color: var(--text-title);
}

.lang-switcher {
    font-size: 0.8rem;
    color: #444;
}

.lang-switcher span {
    color: var(--text-main);
    cursor: pointer;
    transition: color 0.2s;
    padding: 0 4px;
}

.lang-switcher span:hover {
    color: var(--accent-color);
}

/* 核心滚屏主容器 */
.scroll-container {
    margin-left: 280px;
    width: calc(100% - 280px);
    height: 100vh;
    overflow-y: scroll;
    scroll-snap-type: y mandatory;
    scrollbar-width: none;
}

.scroll-container::-webkit-scrollbar {
    display: none;
}

.fullscreen-slide {
    width: 100%;
    height: 100vh;
    scroll-snap-align: start;
    display: flex;
    position: relative;
    padding: 12vh 8%;
    transition: background-color 0.4s ease, border-color 0.4s ease;
}

.fullscreen-slide::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        linear-gradient(var(--grid-color) 1px, transparent 1px),
        linear-gradient(90deg, var(--grid-color) 1px, transparent 1px);
    background-size: 40px 40px;
    z-index: 1;
}

/* 核心核心：通过高级弹性盒实现上下左右错开排列 */
/* 单数屏（1, 3, 5）：定位在左上角 */
.fullscreen-slide:nth-child(odd) {
    justify-content: flex-start;
    align-items: flex-start;
}

/* 双数屏（2, 4）：定位在右下角 */
.fullscreen-slide:nth-child(even) {
    justify-content: flex-end;
    align-items: flex-end;
}

/* ==========================================================================
   SECTION BACKDROP INFRASTRUCTURE (5大业务全屏背景流)
   ========================================================================== */

/* 01 / HARDWARE 硬件开发分屏 */
.slide-hw {
    background-image: 
        linear-gradient(var(--image-overlay-start), var(--image-overlay-end)), 
        url('/assets/images/01.png');
    background-size: cover;       /* 核心：保持图片物理等比例缩放并完全覆盖视口 */
    background-position: center;  /* 核心：无论屏幕怎么变，图片始终居中对齐 */
    border-bottom: 1px solid var(--slide-border);
}

/* 02 / CIRCUITS 电路设计分屏 */
.slide-circuit {
    background-image: 
        linear-gradient(var(--image-overlay-start), var(--image-overlay-end)), 
        url('/assets/images/02.png');
    background-size: cover;
    background-position: center;
    border-bottom: 1px solid var(--slide-border);
}

/* 03 / PCB 印刷板设计分屏 */
.slide-pcb {
    background-image: 
        linear-gradient(var(--image-overlay-start), var(--image-overlay-end)), 
        url('/assets/images/03.png');
    background-size: cover;
    background-position: center;
    border-bottom: 1px solid var(--slide-border);
}

/* 04 / STRUCTURE 结构设计分屏 */
.slide-structure {
    background-image: 
        linear-gradient(var(--image-overlay-start), var(--image-overlay-end)), 
        url('/assets/images/04.png');
    background-size: cover;
    background-position: center;
    border-bottom: 1px solid var(--slide-border);
}

/* 05 / WEB 网页与系统设计分屏 */
.slide-web {
    background-image: 
        linear-gradient(var(--image-overlay-start), var(--image-overlay-end)), 
        url('/assets/images/05.png');
    background-size: cover;
    background-position: center;
}

.slide-content {
    position: relative;
    z-index: 2;
    max-width: 650px;
}

/* 双数屏内文本向右对齐提高空间契合度 */
.fullscreen-slide:nth-child(even) .slide-content {
    text-align: right;
}

.slide-content h2 {
    font-size: clamp(1.8rem, 3.5vw, 2.8rem);
    font-weight: 800;
    color: var(--text-title);
    margin-bottom: 20px;
    letter-spacing: -1px;
    line-height: 1.1;
    transition: color 0.4s;
}

.slide-content p {
    font-size: clamp(0.95rem, 1.2vw, 1.15rem);
    color: var(--text-main);
    line-height: 1.6;
    font-weight: 400;
    transition: color 0.4s;
}

/* 最下方联系表单样式 */
/* ==========================================================================
   CONTACT FORM SECTION DESIGN (精密表单工业视觉)
   ========================================================================== */
.slide-contact {
    background-color: var(--bg-body);
    justify-content: center !important; /* 强制覆盖错位排列，使联系表单全局居中 */
    align-items: center !important;
}

.contact-box {
    width: 100%;
    max-width: 750px;
    z-index: 2;
    background: var(--nav-bg);
    border: 1px solid var(--nav-border);
    padding: 48px;
    border-radius: 4px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.3);
}

.contact-box h2 {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--text-title);
    margin-bottom: 32px;
    letter-spacing: 2px;
    border-left: 3px solid var(--accent-color);
    padding-left: 12px;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}

.form-group {
    position: relative;
    margin-bottom: 28px;
}

/* 动效核心：输入框与区域 */
.form-group input, 
.form-group textarea {
    width: 100%;
    padding: 14px 16px;
    background-color: var(--input-bg);
    border: 1px solid var(--input-border);
    color: var(--text-title);
    border-radius: 4px;
    font-size: 0.5rem;
    outline: none;
    transition: all 0.3s ease;
}

.form-group input:focus,
.form-group textarea:focus {
    border-color: var(--accent-color);
    box-shadow: 0 0 8px rgba(0, 229, 255, 0.1);
}

/* 浮动标签控制 */
.form-group label {
    position: absolute;
    left: 16px;
    top: 14px;
    color: var(--text-main);
    pointer-events: none;
    transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
    font-size: 0.95rem;
    background-color: var(--input-bg);
    padding: 0 4px;
}

/* 当输入框聚焦，或里面已有文字时，标签向上浮动缩小 */
.form-group input:focus ~ label,
.form-group input:not(:placeholder-shown) ~ label,
.form-group textarea:focus ~ label,
.form-group textarea:not(:placeholder-shown) ~ label {
    top: -10px;
    left: 12px;
    font-size: 0.75rem;
    color: var(--accent-color);
    font-weight: 700;
}

.turnstile-container {
    margin-bottom: 24px;
    display: flex;
    justify-content: flex-start;
}

.form-actions {
    display: flex;
    justify-content: flex-end;
    gap: 16px;
}

.form-actions button {
    padding: 12px 28px;
    border-radius: 4px;
    font-size: 0.85rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn-reset {
    background: transparent;
    border: 1px solid var(--btn-border);
    color: var(--btn-text);
}

.btn-reset:hover {
    border-color: #FF3B30;
    color: #FF3B30;
}

.btn-submit {
    background-color: var(--accent-color);
    border: 1px solid var(--accent-color);
    color: #000000;
}

.btn-submit:hover {
    opacity: 0.9;
    transform: translateY(-1px);
}

.form-status {
    margin-top: 20px;
    font-size: 0.9rem;
    text-align: center;
    font-weight: 600;
}

/* “更多”超链接全局设计 */
.more-link {
    display: inline-block;
    margin-top: 24px;
    color: var(--accent-color);
    text-decoration: none;
    font-size: 0.85rem;
    font-weight: 700;
    letter-spacing: 1px;
    transition: color 0.3s, transform 0.3s;
}

.more-link:hover {
    color: var(--text-title);
}

.fullscreen-slide:nth-child(odd) .more-link:hover {
    transform: translateX(6px);
}

.fullscreen-slide:nth-child(even) .more-link:hover {
    transform: translateX(-6px);
}

.mobile-header, .mobile-drawer {
    display: none;
}

/* ==========================================================================
   SITE FOOTER DESIGN (底部版权机能区)
   ========================================================================== */
.site-footer {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    padding: 24px 8%;
    background-color: var(--nav-bg);
    backdrop-filter: blur(10px);
    border-top: 1px solid var(--nav-border);
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: 10;
    transition: background-color 0.4s ease, border-color 0.4s ease;
}

.footer-left {
    display: flex;
    align-items: center;
    gap: 20px;
}

.footer-logo {
    font-size: 0.9rem;
    font-weight: 900;
    letter-spacing: 2px;
    color: var(--text-title);
}

.footer-copy {
    font-size: 0.8rem;
    color: var(--text-main);
}

.footer-right {
    display: flex;
    gap: 24px;
}

.footer-link {
    color: var(--text-main);
    text-decoration: none;
    font-size: 0.8rem;
    font-weight: 500;
    transition: color 0.3s ease;
}

.footer-link:hover {
    color: var(--accent-color);
}

/* 修正：重构移动端抽屉导航为底部向上滑出形态，并修复控制类名不匹配问题 */
.mobile-drawer {
    position: fixed !important;
    top: auto !important; /* 解除贴顶限制 */
    bottom: 0 !important; /* 强制贴紧视口底部 */
    left: 0 !important;
    width: 100% !important; /* 占满全宽 */
    max-width: none !important; /* 取消原有的宽度限制 */
    height: auto !important; /* 高度根据内容自适应 */
    max-height: 85vh !important; /* 最高不超过屏幕高度的 85% */
    background-color: var(--nav-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    z-index: 10000 !important;
    flex-direction: column;
    padding: 30px 20px 40px 20px; /* 增加底部内边距留出安全区 */
    border-top: 1px solid var(--nav-border); /* 边框移至上方 */
    border-right: none !important; /* 清除原有右侧边框 */
    border-radius: 24px 24px 0 0; /* 顶部增加圆角，符合底部抽屉的 UI 直觉 */
    transform: translateY(100%) !important; /* 初始状态：沿 Y 轴向下隐藏于屏幕正下方外侧 */
    visibility: hidden !important;
    transition: transform 0.4s cubic-bezier(0.25, 0.8, 0.25, 1), visibility 0.4s !important;
    display: flex !important; 
}

/* 修正：匹配 forum.js 中 toggle('active') 触发的类名，而非 'show' */
.mobile-drawer.active {
    transform: translateY(0) !important; /* Y 轴回正，向上滑入可视区 */
    visibility: visible !important;
}

/* 左下角主题切换按钮定位系统 */
.fixed-theme-toggle {
    position: fixed;
    left: 20px;
    bottom: 120px; /* 距离底部绝对物理高度 */
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background-color: var(--nav-bg);
    border: 1px solid var(--nav-border);
    color: var(--text-title);
    font-size: 1.2rem;
    cursor: pointer;
    box-shadow: 0 4px 10px rgba(0,0,0,0.3);
    z-index: 9000;
    z-index: 9999;
    pointer-events: auto !important; /* 强制拦截物理点击，防穿透 */
    touch-action: manipulation; /* 消除 iOS 触控事件延迟，提升响应优先级 */
    display: flex;
    justify-content: center;
    align-items: center;
    transition: transform 0.3s ease, border-color 0.3s ease;
}
.fixed-theme-toggle:hover {
    transform: scale(1.1);
    border-color: var(--accent-color);
}
/* 新增：左下角全局浮动汉堡菜单按钮 (默认在 PC 端隐藏) */
.fixed-menu-toggle {
    display: none; /* 默认隐藏，满足需求 */
    position: fixed;
    left: 20px;
    bottom: 60px; /* 定位在主题切换按钮 (120px) 的正下方，留出 16px 间距 (60+44=104) */
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background-color: var(--nav-bg);
    border: 1px solid var(--nav-border);
    color: var(--text-title);
    font-size: 1.2rem;
    cursor: pointer;
    box-shadow: 0 4px 10px rgba(0,0,0,0.3);
    z-index: 9000;
    z-index: 9999;
    pointer-events: auto !important; /* 强制拦截物理点击，防穿透 */
    touch-action: manipulation; /* 消除 iOS 触控事件延迟，提升响应优先级 */
    justify-content: center;
    align-items: center;
    transition: transform 0.3s ease, border-color 0.3s ease;
}

.fixed-menu-toggle:hover {
    transform: scale(1.1);
    border-color: var(--accent-color);
}

/* 新增：移动端视图下释放菜单按钮，否则即使有 JS 驱动也无法进行触控交互 */
@media (max-width: 1023px) {
    .fixed-menu-toggle {
        display: flex !important;
    }
}