* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    scroll-behavior: smooth;
}
:root {
    --bg-main: #1a1e27;
    --bg-second: #2d3440;
    --text-color: #eee;
    --text-opacity: rgba(255,255,255,0.85);
    --card-bg: rgba(255,255,255,0.07);
    --card-border: rgba(255,255,255,0.1);
    --nav-bg: rgba(26, 30, 39, 0.75);
    --accent: #90caf9;
    --accent-light: #64b5f6;
    --dot-color: rgba(100, 180, 255, 0.15);
}
.light-mode {
    --bg-main: #f8fafc;
    --bg-second: #e9edf2;
    --text-color: #222831;
    --text-opacity: rgba(0,0,0,0.75);
    --card-bg: rgba(0,0,0.05);
    --card-border: rgba(0,0,0,0.1);
    --nav-bg: rgba(255, 255, 255, 0.75);
    --accent: #1976d2;
    --accent-light: #2196f3;
    --dot-color: rgba(33, 150, 243, 0.12);
}
.light-mode .card {
    background: rgba(255,255,255,0.65);
    border: 1px solid rgba(0,0,0,0.08);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.08);
}
body {
    font-family: system-ui, -apple-system, sans-serif;
    background: linear-gradient(135deg, var(--bg-main), var(--bg-second));
    color: var(--text-color);
    line-height: 1.7;
    overflow-x: hidden;
    transition: background 0.5s cubic-bezier(0.4, 0, 0.2, 1), color 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}
.container {
    position: relative;
    z-index: 1;
    transition: transform 0.15s ease-out;
    will-change: transform;
}
/* 背景浮动光点 */
.bg-dot {
    position: fixed;
    border-radius: 50%;
    background: var(--dot-color);
    animation: float 12s infinite ease-in-out;
    z-index: 0;
    transition: background 0.5s cubic-bezier(0.4, 0, 0.2, 1), transform 0.12s ease-out;
    will-change: transform;
}
@keyframes float {
    0% {transform: translateY(0) scale(1); opacity:0.2;}
    50% {transform: translateY(-30vh) scale(1.2); opacity:0.6;}
    100% {transform: translateY(0) scale(1); opacity:0.2;}
}

/* 导航栏 */
nav {
    position: fixed;
    width: 100%;
    top: 0;
    padding: 18px 40px;
    background: rgba(26, 30, 39, 0.65);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border-bottom: 1px solid rgba(255,255,255,0.1);
    z-index: 99;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}
.light-mode nav{
    background:rgba(255,255,255,0.65);
}
.logo {
    font-size: 1.4rem;
    font-weight: bold;
    color: var(--accent);
}
.nav-links a {
    color: var(--text-color);
    text-decoration: none;
    margin-left: 28px;
    transition: color 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}
.nav-links a:hover {
    color: var(--accent-light);
}
/* 明暗切换按钮 */
#themeToggle {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    color: var(--text-color);
    width: 40px;
    height:40px;
    border-radius:50%;
    cursor:pointer;
    font-size:1.1rem;
    margin-left:16px;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}
#themeToggle:hover{
    background:var(--accent);
    color:#fff;
    transform: scale(1.08);
}

/* 首页横幅 */
.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 0 20px;
    padding-top: 70px;
    animation: fadeIn 1.2s cubic-bezier(0.4, 0, 0.2, 1) ease-out;
}
@keyframes fadeIn {
    from {opacity:0; transform: translateY(20px);}
    to {opacity:1; transform: translateY(0);}
}
.hero-icon {
    font-size: 5rem;
    color: var(--accent-light);
    margin-bottom: 20px;
    animation: pulse 2.5s infinite ease-in-out;
}
@keyframes pulse {
    0%,100% {transform: scale(1);}
    50% {transform: scale(1.08);}
}
.hero h1 {
    font-size: 3rem;
    margin-bottom: 12px;
}
.hero p {
    font-size: 1.2rem;
    color: var(--text-opacity);
    max-width: 600px;
}
.btn-group {
    margin-top:32px;
}
.btn {
    display: inline-block;
    padding:12px 28px;
    background:var(--accent-light);
    color:#fff;
    text-decoration:none;
    border-radius: 10px;
    margin:0 8px;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}
.btn:hover {
    background:var(--accent);
    transform: translateY(-3px);
}
.btn-outline {
    background:transparent;
    border:1px solid var(--accent-light);
}
.btn-outline:hover {
    background:var(--card-bg);
}

section {
    padding: 90px 20px;
    max-width: 1100px;
    margin: 0 auto;
}
.section-title {
    text-align:center;
    font-size:2rem;
    margin-bottom:48px;
    color:var(--accent);
}

/* 滚动渐入动画 - 优化流畅度 */
.fade-in {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 0.8s cubic-bezier(0.4, 0, 0.2, 1), transform 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}
.fade-in.active {
    opacity:1;
    transform: translateY(0);
}

/* 关于我 */
.about {
    display:grid;
    grid-template-columns: 1fr 1fr;
    gap:40px;
    align-items:center;
}
.about-text p {
    color: var(--text-opacity);
    margin-bottom:16px;
}
.skill-list {
    display:flex;
    flex-wrap:wrap;
    gap:10px;
}
.skill-tag {
    padding:6px 14px;
    background:var(--card-bg);
    border-radius:6px;
    font-size:0.9rem;
    border:1px solid var(--card-border);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}
.skill-tag:hover{
    background:var(--accent);
    color:#fff;
}

/* 项目卡片 */
.projects {
    display:grid;
    grid-template-columns: repeat(auto-fit, minmax(280px,1fr));
    gap:24px;
}
/* 项目卡片 - 液态玻璃效果 */
.card {
    background: rgba(255,255,255,0.06);
    border: 1px solid rgba(255,255,255,0.12);
    border-radius: 16px;
    padding:24px;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.18);
    transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
    cursor: pointer;
}
.card:hover {
    transform: translateY(-8px);
    border-color:rgba(144, 202, 249, 0.4);
    box-shadow: 0 12px 40px rgba(100,180,255,0.16);
}
.card h3 {
    margin-bottom:10px;
    color:var(--accent);
}
.card p {
    color: var(--text-opacity);
    font-size:0.95rem;
}
.card-tag-group{
    margin-top:14px;
    display:flex;
    flex-wrap:wrap;
    gap:6px;
}
.card-tag{
    font-size:0.75rem;
    padding:3px 8px;
    border-radius:4px;
    background:rgba(100,180,255,0.12);
    color:var(--accent-light);
}

/* 弹窗样式 */
.modal-overlay{
    position:fixed;
    inset:0;
    background:rgba(0,0,0,0.65);
    backdrop-filter: blur(4px);
    z-index:100;
    display:none;
    align-items:center;
    justify-content:center;
    padding:20px;
}
.modal-overlay.open{
    display:flex;
}
.modal-box{
    width:100%;
    max-width:700px;
    max-height:85vh;
    overflow-y:auto;
    background: rgba(26,30,39,0.72);
    border:1px solid rgba(255,255,255,0.12);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-radius:20px;
    padding:32px;
    transition:0.4s;
}
.light-mode .modal-box{
    background:rgba(255,255,255,0.75);
}
.modal-box h2{
    color:var(--accent);
    margin-bottom:16px;
}
.modal-desc{
    color:var(--text-opacity);
    line-height:1.8;
    margin-bottom:20px;
}
.modal-close{
    float:right;
    border:none;
    background:var(--card-bg);
    color:var(--text-color);
    width:36px;
    height:36px;
    border-radius:50%;
    font-size:18px;
    cursor:pointer;
}
.modal-close:hover{
    background:var(--accent-light);
    color:#fff;
}
.modal-links a{
    display:inline-block;
    margin-right:12px;
    padding:8px 16px;
    background:var(--accent-light);
    color:#fff;
    text-decoration:none;
    border-radius:8px;
    margin-top:8px;
}
.modal-links a.btn-outline{
    background:transparent;
    border:1px solid var(--accent-light);
}

/* 联系 */
.contact {
    text-align:center;
}
.contact-links a {
    font-size:2rem;
    color:var(--accent);
    margin:0 12px;
    text-decoration:none;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}
.contact-links a:hover {
    color:var(--accent-light);
    transform: translateY(-4px);
}
footer {
    text-align:center;
    padding:30px;
    color: var(--text-opacity);
    font-size:0.9rem;
}

/* 回到顶部按钮 */
#backTop {
    position: fixed;
    right: 30px;
    bottom:30px;
    width:48px;
    height:48px;
    border-radius:50%;
    background:var(--accent-light);
    color:#fff;
    border:none;
    font-size:1.2rem;
    cursor:pointer;
    box-shadow:0 4px 16px rgba(0,0,0,0.25);
    z-index:98;
    opacity:0;
    visibility:hidden;
    transform: translateY(20px);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}
#backTop.show{
    opacity:1;
    visibility:visible;
    transform: translateY(0);
}
#backTop:hover{
    background:var(--accent);
    transform: translateY(-4px);
}

/* 移动端适配 */
@media (max-width:768px){
    nav {
        padding:14px 20px;
    }
    .nav-links {
        display:flex;
        align-items:center;
    }
    .nav-links a {
        margin-left:14px;
    }
    .hero h1 {
        font-size:2.2rem;
    }
    .about {
        grid-template-columns:1fr;
    }
    #backTop{
        right:18px;
        bottom:18px;
        width:42px;
        height:42px;
    }
}

/* 友情链接 */
.friend-link {
    text-align: center;
    padding: 24px 20px 30px;
    border-top: 1px solid var(--card-border);
    margin-top: 60px;
}
.friend-link p {
    color: var(--text-opacity);
    font-size: 0.9rem;
    margin-bottom: 12px;
    letter-spacing: 2px;
}
.friend-link a {
    display: inline-block;
    transition: opacity 0.3s ease, transform 0.3s ease;
}
.friend-link a:hover {
    opacity: 0.85;
    transform: scale(1.04);
}
.friend-link img {
    max-width: 120px;
    width: 100%;
    height: auto;
    display: block;
    margin: 0 auto;
    /* 关键：把竖图横过来 */
    transform: rotate(-90deg);
}