*{box-sizing:border-box}

body{

margin:0;

font-family:Arial,Helvetica,sans-serif;

background:#f6f8fc;

color:#172033;

line-height:1.7

}

a{text-decoration:none;color:#155eef}

.header{

background:#fff;

border-bottom:1px solid #e7ebf2;

position:sticky;

top:0;

z-index:10

}

.nav{

max-width:1100px;

margin:auto;

padding:16px 24px;

display:flex;

justify-content:space-between;

align-items:center;

gap:20px

}

.brand{

font-weight:800;

letter-spacing:.4px;

color:#172033

}

.back{

font-size:14px;

font-weight:600

}

main{

max-width:850px;

margin:auto;

padding:60px 24px 80px

}

.breadcrumb{

font-size:14px;

margin-bottom:28px;

color:#64748b

}

.tag{

display:inline-block;

font-size:13px;

font-weight:700;

letter-spacing:.08em;

color:#155eef;

margin-bottom:14px

}

h1{

font-size:clamp(32px,6vw,54px);

line-height:1.15;

margin:0 0 20px;

letter-spacing:-1.5px

}

.lead{

font-size:20px;

color:#475569;

margin-bottom:40px

}

.note{

background:#eef4ff;

border-left:4px solid #155eef;

padding:18px 20px;

border-radius:8px;

margin:30px 0

}

section{margin-top:48px}

h2{

font-size:30px;

line-height:1.25;

margin-bottom:16px

}

h3{

font-size:21px;

margin-top:28px

}

p{margin:14px 0}

ul{

padding-left:24px

}

li{margin:10px 0}

.card{

background:#fff;

border:1px solid #e7ebf2;

border-radius:16px;

padding:24px;

margin:24px 0;

box-shadow:0 4px 18px rgba(15,23,42,.04)

}

.grid{

display:grid;

grid-template-columns:repeat(2,minmax(0,1fr));

gap:16px

}

.grid .card{margin:0}

.related{

background:#fff;

border-top:1px solid #e7ebf2;

padding:50px 24px

}

.related-inner{

max-width:850px;

margin:auto

}

.related-links{

display:flex;

flex-wrap:wrap;

gap:12px;

margin-top:18px

}

.related-links a{

background:#f1f5f9;

padding:12px 16px;

border-radius:10px;

font-weight:600

}

footer{

text-align:center;

padding:28px;

font-size:14px;

color:#64748b

}

@media(max-width:650px){

.nav{padding:14px 18px}

main{padding:42px 18px 60px}

.grid{grid-template-columns:1fr}

h2{font-size:26px}

}

.table-of-contents{

  margin:24px 0;

  border:1px solid #e1e6ee;

  border-radius:12px;

  background:#f8fafc;

  overflow:hidden;

}



.toc-toggle{

  width:100%;

  border:0;

  background:#071b35;

  color:#fff;

  padding:16px 18px;

  font-size:16px;

  font-weight:700;

  display:flex;

  justify-content:space-between;

  align-items:center;

  cursor:pointer;

}



.toc-arrow{

  font-size:18px;

  line-height:1;

}



.toc-content{

  display:none;

  padding:14px 22px;

}



.table-of-contents.open .toc-content{

  display:block;

}



.toc-content ul{

  margin:0;

  padding-left:18px;

}



.toc-content li{

  margin:10px 0;

}



.toc-content a{

  color:#0d3b66;

  text-decoration:none;

  font-weight:600;

}



.toc-content a:hover{

  text-decoration:underline;

}



@media(max-width:600px){

  .toc-toggle{

    padding:15px;

  }



  .toc-content{

    padding:12px 18px;

  }

}

.author-box{

    margin:30px 0;

    padding:20px;

    border:1px solid #ddd;

    border-radius:10px;

    background:#f8f9fa;

}

.author-box strong{

    display:block;

    font-size:18px;

    margin-bottom:5px;

}

.author-box span{

    display:block;

    font-size:14px;

    margin-bottom:12px;

    color:#555;

}

.author-box p{

    margin:0;

    line-height:1.6;

}