:root {
    /* 调色板 - 默认采用 Paper White 风格 */
    --bg-color: #f4f1ea;
    --text-primary: #2b2b2b;
    --text-secondary: #5e5e5e;
    --accent: #cd5c5c; /* 印度红，用于强调 */
    --line-color: #dcd9d2;
    
    --font-cn: 'Noto Serif SC', serif;
    --font-en: 'Cormorant Garamond', serif;
    
    --page-padding: 6vw;
    --header-height: 80px;
}

/* 深色模式 / 晚间模式 */
body.dark-mode {
    --bg-color: #1a1a1a;
    --text-primary: #e0e0e0;
    --text-secondary: #999;
    --accent: #eebb4d;
    --line-color: #333;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-cn);
    background-color: var(--bg-color);
    color: var(--text-primary);
    overflow: hidden; /* 防止滚动，做成应用感 */
    height: 100vh;
    transition: background-color 1.5s ease, color 1.5s ease;
}

/* 噪点纹理 */
.noise-overlay {
    position: fixed;
    top: 0; left: 0; width: 100%; height: 100%;
    pointer-events: none;
    z-index: 999;
    opacity: 0.05;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noiseFilter'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.65' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noiseFilter)'/%3E%3C/svg%3E");
}

/* 装饰边框 */
.frame-border {
    position: fixed;
    top: 1.5rem; bottom: 1.5rem; left: 1.5rem; right: 1.5rem;
    border: 1px solid var(--text-primary);
    opacity: 0.1;
    pointer-events: none;
    z-index: 10;
}

/* 导航栏 */
.app-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: var(--header-height);
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 var(--page-padding);
    z-index: 100;
}

.logo {
    font-family: var(--font-en);
    font-weight: 700;
    letter-spacing: 0.2em;
    font-size: 1.2rem;
    text-transform: uppercase;
}

.nav-menu {
    display: flex;
    gap: 3rem;
}

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-family: var(--font-cn);
    font-size: 0.9rem;
    position: relative;
    transition: color 0.3s;
}

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

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 50%;
    transform: translateX(-50%);
    width: 4px;
    height: 4px;
    background-color: var(--accent);
    border-radius: 50%;
}

.lang-btn {
    background: none;
    border: none;
    font-family: var(--font-en);
    cursor: pointer;
    color: var(--text-primary);
    opacity: 0.5;
    font-style: italic;
    font-size: 1rem;
    transition: opacity 0.3s;
}

.lang-btn:hover {
    opacity: 1;
}

/* 主容器 */
.app-container {
    height: 100%;
    width: 100%;
    padding-top: var(--header-height);
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
}

/* 页脚 */
.app-footer {
    position: fixed;
    bottom: 0;
    width: 100%;
    padding: 1.5rem var(--page-padding);
    display: flex;
    justify-content: space-between;
    font-family: var(--font-en);
    font-size: 0.8rem;
    opacity: 0.4;
    z-index: 100;
}

.app-footer .separator {
    margin: 0 10px;
}

/* 通用排版 */
h1 {
    font-family: var(--font-cn);
    font-weight: 300;
    line-height: 1.4;
}

p {
    line-height: 1.8;
}

/* 英文下的特殊字体 */
body[data-lang="en"] {
    font-family: var(--font-en);
}
body[data-lang="en"] .nav-link {
    font-family: var(--font-en);
    text-transform: lowercase;
    font-style: italic;
    font-size: 1.1rem;
}

/* 响应式 */
@media (max-width: 768px) {
    .frame-border { display: none; }
    .nav-menu { gap: 1.5rem; }
    :root { --page-padding: 1.5rem; }
}