/* ===== 全局重置与变量 ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* 暗色主题 */
body.dark-theme {
    --bg-color: #0a0c0f;
    --text-primary: #c0dcff;
    --text-secondary: #b0ccee;
    --element-bg: #1b212a;
    --element-bg-hover: #2d3542;
    --border-accent: #1f3540;
    --avatar-bg: #2a3440;
    --btn-text: #c0dcff;
    --slider-color: #c0dcff;
}

/* 亮色主题（背景纯白） */
body.light-theme {
    --bg-color: #ffffff;
    --text-primary: #4f3f30;
    --text-secondary: #6b5847;
    --element-bg: #f0eae2;
    --element-bg-hover: #e0d6cc;
    --border-accent: #cbb59b;
    --avatar-bg: #dacbbd;
    --btn-text: #4f3f30;
    --slider-color: #4f3f30;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.6;
    padding: 2rem 1.5rem;
    max-width: 1200px;
    margin: 0 auto;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    transition: background-color 0.2s, color 0.2s;
}

:root {
    --corner-radius: 16px;
}

/* 所有可交互元素指针变化 */
a, button, .nav-item, .resource-link, .theme-btn, .social-link {
    cursor: pointer;
    text-decoration: none;
}

/* ===== 顶部导航栏 ===== */
.top-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.selection-bar {
    position: relative;
    display: flex;
    gap: 0.8rem;
    flex-wrap: wrap;
    overflow: visible;
}

.nav-item {
    position: relative;
    background-color: var(--element-bg);
    color: var(--text-primary);
    padding: 0.7rem 1.8rem;
    font-size: 1.1rem;
    font-weight: 450;
    border-radius: var(--corner-radius) 0 var(--corner-radius) 0;
    transition: background-color 0.15s;
    z-index: 1;
    white-space: nowrap;
}

.nav-item:hover {
    background-color: var(--element-bg-hover);
}

/* 滑块：高度4px，两端半圆，颜色与文字一致 */
.slider {
    position: absolute;
    bottom: 0;
    left: 0;
    height: 4px;
    background-color: var(--slider-color);
    border-radius: 4px;        /* 半圆边缘 */
    transition: left 0.25s ease, width 0.25s ease;
    pointer-events: none;
    z-index: 3;
}

/* 主题切换按钮 */
.theme-btn {
    background-color: var(--element-bg);
    color: var(--btn-text);
    border: none;
    padding: 0.6rem 1.4rem;
    font-size: 1rem;
    font-weight: 450;
    border-radius: 0 var(--corner-radius) 0 var(--corner-radius);
    transition: background-color 0.15s;
    line-height: 1.2;
    white-space: nowrap;
}

.theme-btn:hover {
    background-color: var(--element-bg-hover);
}

/* ===== 主内容区域 ===== */
main {
    flex: 1;                    /* 撑满剩余高度 */
    display: flex;
    flex-direction: column;
}

/* 页面容器：flex:1 使其自动占满 main 剩余高度 */
.pages-container {
    position: relative;
    flex: 1;                    /* 关键：高度由flex决定，等于剩余空间 */
    width: 100%;
}

/* 所有页面默认绝对定位，实现切换动画 */
.page {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.3s, transform 0.3s;
    pointer-events: none;
}

/* 激活页面：相对定位，height:100% 继承父容器高度，并启用flex居中 */
.page.active-page {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
    position: relative;         /* 脱离绝对定位，撑开高度 */
    height: 100%;               /* 占满 pages-container 高度 */
}

/* ===== 个人简介页面（垂直居中） ===== */
#profile-page.active-page {
    display: flex;
    align-items: center;        /* 垂直居中 */
    justify-content: center;    /* 水平居中 */
}

.profile-container {
    display: flex;
    align-items: center;
    gap: 4rem;
    flex-wrap: wrap;
    justify-content: center;
    width: 100%;
    padding: 2rem 0;
}

/* 头像：200px，混合圆角 */
.avatar {
    width: 250px;
    height: 250px;
    border-radius: var(--corner-radius) 0 var(--corner-radius) 0;
    object-fit: cover;
    box-shadow: 0 0 0 1px var(--border-accent);
    flex-shrink: 0;
}

/* 简介文字 */
.profile-text {
    text-align: left;
    max-width: 700px;
}

/* 用户名：大号 + 律动动画 */
.username {
    font-size: 2.8rem;
    font-weight: 400;
    letter-spacing: 1px;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    line-height: 1.3;
    animation: float 2s ease-in-out infinite;
}

@keyframes float {
    0% { transform: translateY(0); }
    50% { transform: translateY(-6px); }
    100% { transform: translateY(0); }
}

.tagline {
    font-size: 1.3rem;
    color: var(--text-secondary);
    font-weight: 300;
    border-left: 3px solid var(--border-accent);
    padding-left: 1.2rem;
    margin-bottom: 1.5rem;
}

/* 社交链接 */
.social-links {
    display: flex;
    gap: 2rem;
    flex-wrap: wrap;
    margin-top: 1rem;
}

.social-link {
    color: var(--text-primary);
    font-size: 1.2rem;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: color 0.15s, border-color 0.15s;
    border-bottom: 1px solid transparent;
    padding-bottom: 0.2rem;
}

.social-link:hover {
    color: var(--text-secondary);
    border-bottom-color: var(--border-accent);
}

.social-link i {
    font-size: 1.5rem;
}

/* ===== 资源链接页面 ===== */
#resources-page h2,
#admin-page h2 {
    font-size: 1.8rem;
    font-weight: 400;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    border-bottom: 1px solid var(--border-accent);
    padding-bottom: 0.5rem;
}

.resource-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.resource-link {
    display: inline-block;
    background-color: var(--element-bg);
    color: var(--text-primary);
    padding: 0.7rem 1.8rem;
    border-radius: var(--corner-radius) 0 var(--corner-radius) 0;
    transition: background-color 0.15s, padding 0.1s;
}

.resource-link:hover {
    background-color: var(--element-bg-hover);
    padding-left: 2.2rem;
}

a:visited,
a:link {
    color: var(--text-primary);
}

/* ===== 管理面板页面 ===== */
.admin-note {
    margin-bottom: 1.5rem;
    color: var(--text-secondary);
    font-style: italic;
}

.admin-placeholder {
    display: inline-block;
    background-color: var(--element-bg);
    color: var(--text-secondary);
    padding: 0.9rem 2rem;
    border-radius: 0 var(--corner-radius) 0 var(--corner-radius);
    border: 1px dashed var(--border-accent);
    font-size: 1rem;
    cursor: default;
    transition: background-color 0.1s;
}

/* ===== 响应式 ===== */
@media (max-width: 650px) {
    body {
        padding: 1.5rem 1rem;
    }
    .username {
        font-size: 2.2rem;
    }
    .avatar {
        width: 160px;
        height: 160px;
    }
    .profile-container {
        gap: 2rem;
    }
    .social-links {
        gap: 1.5rem;
        justify-content: center;
    }
}

@media (max-width: 450px) {
    .top-bar {
        flex-direction: column;
        align-items: stretch;
    }
    .theme-btn {
        align-self: flex-end;
    }
    .profile-text {
        text-align: center;
    }
    .tagline {
        border-left: none;
        border-top: 2px solid var(--border-accent);
        padding-top: 0.8rem;
        padding-left: 0;
    }
    .social-links {
        justify-content: center;
    }
}