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

body{
    font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif;
    background:#f5f7fb;
    color:#222;
    line-height:1.8;
}

a{
    text-decoration:none;
}

img{
    max-width:50%;
    display:block;
}

.container{
    display:flex;
    min-height:100vh;
}

.sidebar{
    width:260px;
    background:#111827;
    padding:30px 20px;
    position:fixed;
    left:0;
    top:0;
    bottom:0;
    overflow:auto;
}

.logo{
    color:#fff;
    font-size:26px;
    font-weight:bold;
    margin-bottom:40px;
}

.menu{
    display:flex;
    flex-direction:column;
    gap:15px;
}

.menu a{
    background:#1f2937;
    color:#fff;
    padding:14px 16px;
    border-radius:12px;
    transition:0.3s;
    font-size:15px;
}

.menu a:hover{
    background:#2563eb;
    transform:translateX(5px);
}

.content{
    margin-left:260px;
    width:100%;
    padding:40px;
}

.hero{
    background:linear-gradient(135deg,#2563eb,#1d4ed8);
    color:#fff;
    border-radius:24px;
    padding:50px;
    margin-bottom:30px;
}

.hero h1{
    font-size:42px;
    margin-bottom:20px;
}

.hero p{
    font-size:18px;
    opacity:0.95;
}

.card{
    background:#fff;
    border-radius:20px;
    padding:30px;
    margin-bottom:25px;
    box-shadow:0 5px 20px rgba(0,0,0,0.05);
}

.card h2{
    margin-bottom:20px;
    font-size:28px;
    color:#111827;
}

.card p{
    margin-bottom:16px;
    color:#444;
}

.step-img{
    width:100%;
    border-radius:16px;
    margin-top:15px;
    margin-bottom:20px;
}

.notice{
    background:#eff6ff;
    border-left:5px solid #2563eb;
    padding:18px;
    border-radius:10px;
    margin-top:15px;
}

.buy-btn{
    display:inline-block;
    margin-top:20px;
    background:#2563eb;
    color:#fff;
    padding:14px 28px;
    border-radius:12px;
    font-size:16px;
    transition:0.3s;
}

.buy-btn:hover{
    background:#1d4ed8;
}

.article-pagination{
    display:flex;
    gap:30px;
    margin-top:60px;
    margin-bottom:50px;
    flex-wrap:wrap;
}

.article-card{
    flex:1;
    min-width:280px;
    background:#fff;
    padding:24px;
    border-radius:20px;
    box-shadow:0 5px 20px rgba(0,0,0,0.05);
    border:1px solid #edf1f7;
    transition:0.3s;
}

.article-card:hover{
    transform:translateY(-5px);
    border-color:#2563eb;
    box-shadow:0 12px 30px rgba(37,99,235,0.12);
}

.small-title{
    display:block;
    color:#2563eb;
    font-size:14px;
    margin-bottom:10px;
    font-weight:600;
}

.big-title{
    display:block;
    color:#111827;
    font-size:20px;
    font-weight:700;
    line-height:1.6;
}

.article-card:hover .big-title{
    color:#2563eb;
}

.footer{
    text-align:center;
    color:#666;
    padding:30px 0;
}

@media(max-width:900px){

    .sidebar{
        position:relative;
        width:100%;
        height:auto;
    }

    .content{
        margin-left:0;
        padding:20px;
    }

    .container{
        flex-direction:column;
    }

    .hero{
        padding:30px;
    }

    .hero h1{
        font-size:30px;
    }

    .card{
        padding:22px;
    }

    .article-pagination{
        gap:20px;
        margin-top:40px;
    }

}