* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Microsoft Yahei, sans-serif;
}

body {
    overflow-x: hidden;
    background: #050818;
    color: #fff;
}

/* ======================
   动态背景
   ====================== */
.background-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
}

/* 星空 */
.stars {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}
.star {
    position: absolute;
    width: 2px;
    height: 2px;
    background: #fff;
    border-radius: 50%;
    opacity: 0.8;
    animation: twinkle 3s infinite ease-in-out;
}
@keyframes twinkle {
    0%, 100% { opacity: 0.3; }
    50% { opacity: 1; }
}

/* 星云 */
.nebula {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 20% 30%, rgba(59, 130, 246, 0.15) 0%, transparent 40%),
        radial-gradient(circle at 70% 60%, rgba(34, 197, 94, 0.1) 0%, transparent 40%),
        radial-gradient(circle at 40% 80%, rgba(147, 197, 253, 0.05) 0%, transparent 40%);
    animation: nebulaMove 20s infinite ease-in-out;
}
@keyframes nebulaMove {
    0%, 100% { 
        background-position: 
            20% 30%, 
            70% 60%, 
            40% 80%;
    }
    50% { 
        background-position: 
            25% 35%, 
            65% 65%, 
            35% 75%;
    }
}

/* ======================
   导航栏
   ====================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    padding: 15px 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: 999;
    background: rgba(0, 0, 0, 0.3);
    backdrop-filter: blur(15px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}
.logo {
    font-size: 20px;
    font-weight: 600;
    color: #4ade80;
    text-shadow: 0 0 10px rgba(74, 222, 128, 0.5);
}
.logo i {
    margin-right: 8px;
    animation: rotateIcon 5s linear infinite;
}
@keyframes rotateIcon {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}
.lang-btn {
    padding: 8px 18px;
    border: 1px solid #4ade80;
    border-radius: 30px;
    font-size: 14px;
    cursor: pointer;
    transition: all 0.3s ease;
    background: rgba(74, 222, 128, 0.1);
}
.lang-btn:hover {
    background: #4ade80;
    color: #000;
    box-shadow: 0 0 15px rgba(74, 222, 128, 0.5);
}

/* ======================
   主容器
   ====================== */
.container {
    position: relative;
    z-index: 2;
    min-height: 100vh;
    padding-top: 120px;
    text-align: center;
    padding-left: 20px;
    padding-right: 20px;
}

/* ======================
   动态粒子地球
   ====================== */
.earth-box {
    padding: 20px 0;
    display: flex;
    justify-content: center;
    align-items: center;
}
#earthCanvas {
    width: 250px;
    height: 250px;
    filter: drop-shadow(0 0 30px rgba(59, 130, 246, 0.5));
}

/* ======================
   标题内容
   ====================== */
.content h1 {
    font-size: 42px;
    margin: 20px 0 10px;
    color: #ffffff;
    text-shadow: 0 0 20px rgba(59, 130, 246, 0.5);
    background: linear-gradient(to right, #4ade80, #3b82f6);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}
.content .desc {
    font-size: 18px;
    color: #ccc;
    max-width: 600px;
    margin: 0 auto 40px;
    line-height: 1.8;
    text-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
}

/* ======================
   卡片网格布局
   ====================== */
.card-grid {
    max-width: 1000px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 25px;
    margin-bottom: 60px;
}
.card {
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(15px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 20px;
    padding: 35px 25px;
    transition: all 0.4s ease;
    position: relative;
    overflow: hidden;
}
.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(59, 130, 246, 0.1), transparent);
    transition: left 0.6s ease;
}
.card:hover::before {
    left: 100%;
}
.card:hover {
    transform: translateY(-10px);
    border-color: #4ade80;
    box-shadow: 0 15px 35px rgba(74, 222, 128, 0.2);
}
.card-icon {
    font-size: 40px;
    color: #4ade80;
    margin-bottom: 20px;
    filter: drop-shadow(0 0 10px rgba(74, 222, 128, 0.5));
}
.card h3 {
    font-size: 19px;
    margin-bottom: 12px;
    color: #ffffff;
}
.card p {
    font-size: 15px;
    color: #bbb;
    line-height: 1.8;
}

/* 卡片悬停光效 */
.light-effect {
    position: absolute;
    width: 100px;
    height: 100px;
    background: radial-gradient(circle, rgba(255, 255, 255, 0.3) 0%, transparent 70%);
    border-radius: 50%;
    pointer-events: none;
    transform: translate(-50%, -50%);
    z-index: 1;
    mix-blend-mode: screen;
    filter: blur(10px);
}

/* ======================
   底部
   ====================== */
.footer {
    font-size: 15px;
    color: #888;
    padding-bottom: 30px;
    text-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
}

/* ======================
   手机响应式适配
   ====================== */
@media (max-width: 900px) {
    .card-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    .content h1 {
        font-size: 34px;
    }
    #earthCanvas {
        width: 220px;
        height: 220px;
    }
}
@media (max-width: 500px) {
    .navbar {
        padding: 15px 20px;
    }
    .logo {
        font-size: 17px;
    }
    .lang-btn {
        padding: 7px 15px;
        font-size: 13px;
    }
    #earthCanvas {
        width: 180px;
        height: 180px;
    }
    .content h1 {
        font-size: 28px;
    }
    .content .desc {
        font-size: 16px;
    }
    .card-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    .card {
        padding: 30px 20px;
    }
    .card-icon {
        font-size: 36px;
    }
    .footer {
        font-size: 14px;
    }
}