*{box-sizing:border-box}

body{margin:0;font-family:Arial,Helvetica,sans-serif;background:#f6f8fc;color:#172033;line-height:1.75}

a{text-decoration:none;color:#174ea6}

.header{background:#fff;border-bottom:1px solid #e5eaf1;position:sticky;top:0;z-index:10}

.nav{max-width:1100px;margin:auto;padding:18px 22px;display:flex;justify-content:space-between;align-items:center;gap:20px}

.brand{font-weight:800;color:#172033;letter-spacing:.3px}

.back{font-size:14px}

main{max-width:900px;margin:0 auto;padding:55px 22px 70px}

.badge{display:inline-block;background:#eaf2ff;color:#174ea6;padding:6px 12px;border-radius:999px;font-size:12px;font-weight:700;letter-spacing:.5px}

h1{font-size:42px;line-height:1.18;margin:18px 0}

h2{margin-top:45px;font-size:27px;line-height:1.3}

h3{margin-top:28px;font-size:21px}

p{font-size:17px;color:#39465c}

.lead{font-size:20px;color:#4a5870}

.box{background:#fff;border:1px solid #e5eaf1;border-radius:16px;padding:25px;margin:28px 0}

.note{border-left:4px solid #174ea6}

ul{padding-left:24px}

li{margin:10px 0;color:#39465c}

.links{display:grid;grid-template-columns:repeat(auto-fit,minmax(210px,1fr));gap:15px;margin-top:25px}

.link-card{display:block;background:#fff;border:1px solid #e5eaf1;border-radius:14px;padding:18px;font-weight:700}

.footer{background:#172033;color:#dce3ef;padding:35px 22px;text-align:center}

.footer a{color:#fff}

@media(max-width:650px){

h1{font-size:34px}

main{padding-top:38px}

.nav{padding:15px 16px}

}

.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;

}