*{box-sizing:border-box}

html{scroll-behavior:smooth}

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,ol{

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;

}