:root{
    --c1: #ecf39e;
    --c2: #90a955;
    --c3: #4f772d;
    --c4: #31572c;
    --c5: #132a13;
    --bg: linear-gradient(180deg,#f6f8e2 0%, #eef3c8 100%);
    --surface: #ffffff;
    --muted: rgba(19,42,19,0.7);
    --radius: 12px;
    --container: 1000px;
    font-family: Inter, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
  }

  *{box-sizing:border-box}
  html,body{height:100%}
  body{
    margin:0;
    background:#eef3c8;
    color:var(--c5);
    -webkit-font-smoothing:antialiased;
    -moz-osx-font-smoothing:grayscale;
    line-height:1.5;
  }

  .container{
    max-width:var(--container);
    margin:0 auto;
    padding:16px;
  }

  /* HEADER - VIENA EILUTĖ */
  .site-header{
    background: linear-gradient(90deg,var(--c4),var(--c3));
    color:#fff;
    padding:14px 0;
    border-bottom:4px solid rgba(0,0,0,0.06);
  }
  .site-header .container{
    display:flex;
    align-items:center;
    justify-content:space-between; /* kairė - tu; dešinė - mygtukas */
    gap:12px;
  }

  /* Kairėje grupė (pavadinimas + tekstukas) */
  .header-left{
    display:flex;
    align-items:center;
    gap:14px;
    min-width:0; /* leidžia tekstui sutrumptėti */
  }

  .brand{
    display:flex;
    align-items:center;
    gap:10px;
    font-size:1.4rem;
    font-weight:800;
    margin:0;
    white-space:nowrap;
  }
  .brand .logo{
    width:44px;height:44px;border-radius:10px;display:grid;place-items:center;
    background:linear-gradient(135deg, rgba(236,243,158,0.12), rgba(144,169,85,0.12));
    color:#fff;font-weight:800;border:1px solid rgba(255,255,255,0.08);
  }

  .tagline-inline{
    color: rgba(255,255,255,0.95);
    font-size:0.98rem;
    margin:0;
    /* allow wrapping if space is tight */
    display:block;
    max-width:48ch;
    overflow:hidden;
    text-overflow:ellipsis;
    white-space:nowrap;
  }

  /* Instagram mygtukas dešinėje */
  .social-btn{
    display:inline-flex;
    align-items:center;
    gap:10px;
    padding:10px 14px;
    border-radius:999px;
    background:linear-gradient(90deg,var(--c1),var(--c2));
    color:var(--c5);
    text-decoration:none;
    font-weight:700;
    border:1px solid rgba(19,42,19,0.06);
    box-shadow:0 8px 22px rgba(19,42,19,0.08);
    transition:transform .12s ease,box-shadow .12s ease;
    white-space:nowrap;
  }
  .social-btn .ico{ width:26px;height:26px;display:grid;place-items:center;border-radius:8px;background:#fff;color:var(--c4); font-weight:800; }
  .social-btn:hover{ transform:translateY(-3px); box-shadow:0 14px 36px rgba(19,42,19,0.12); }
  .social-btn:active{ transform:translateY(-1px); }

  /* MAIN */
  main{ padding:22px 0; }
  .intro h2{ margin:0 0 12px 0; color:var(--c4); font-size:1.25rem; }

  .grid{
    display:grid;
    grid-template-columns: repeat(auto-fit, minmax(250px,1fr));
    gap:16px;
    margin-top:12px;
  }
  .card{
    display:flex; flex-direction:column; gap:10px;
    padding:16px; border-radius:12px;
    background: linear-gradient(180deg, rgba(255,255,255,0.96), rgba(245,250,235,0.96));
    border:1px solid rgba(15,37,13,0.04); box-shadow:0 8px 28px rgba(19,42,19,0.06);
    text-decoration:none; color:var(--c5);
    transition:transform .12s ease,box-shadow .12s ease;
  }
  .card:hover,.card:focus-visible{ transform:translateY(-6px); box-shadow:0 20px 40px rgba(19,42,19,0.12); outline:none; }
  .card-header{ display:flex; align-items:center; gap:12px; }
  .card-icon{ width:50px;height:50px;border-radius:12px;display:grid;place-items:center;font-size:22px;
    background: linear-gradient(180deg, rgba(79,119,45,0.12), rgba(49,87,44,0.06)); border:1px solid rgba(79,119,45,0.06); }
  .card h3{ margin:0; font-size:1.02rem; }

  /* footer small */
  footer{ padding:18px 0; text-align:center; color:var(--muted); font-size:0.95rem; }

  /* responsive: on very small screens, allow wrapping */
  @media (max-width:500px){
    .site-header .container{ flex-direction:column; align-items:flex-start; gap:8px; }
    .header-left{ width:100%; gap:10px; }
    .tagline-inline{ white-space:normal; max-width:100%; }
    .social-btn{ align-self:flex-end; }
  }

  /* accessibility */
  :focus-visible{ outline:3px solid rgba(79,119,45,0.18); border-radius:8px; }

  /* Breadcrumbs */
.breadcrumbs {
  max-width: 1000px;
  margin: 10px auto;
  padding: 6px 16px;
  background: transparent;
  color: var(--c5, #132a13);
  font-size: 0.95rem;
}
.breadcrumbs ol{
  list-style:none;
  display:flex;
  gap:10px;
  align-items:center;
  margin:0;
  padding:0;
  flex-wrap:wrap;
}
.breadcrumbs li{
  display:inline-flex;
  align-items:center;
  gap:10px;
}
.breadcrumbs a{
  color: var(--c4, #31572c);
  text-decoration: none;
  font-weight:600;
}
.breadcrumbs a:hover, .breadcrumbs a:focus{ text-decoration:underline; outline:none; }
.breadcrumbs .sep{
  color: rgba(19,42,19,0.35);
  user-select: none;
}
.breadcrumbs .current{
  color: rgba(19,42,19,0.8);
  font-weight:700;
}
/* mobile: smaller text */
@media (max-width:500px){
  .breadcrumbs { font-size:0.92rem; padding:6px 12px; }
  .breadcrumbs ol{ gap:8px; }
}

.container { max-width:1000px; margin:20px auto; padding:0 16px; }
    h1{ color:#31572c; margin-bottom:6px; }
    .lead{ color:#4f772d; margin-top:0; }
    section { margin-top:18px; }
    table.sets {
      width:100%;
      border-collapse:collapse;
      margin:12px 0;
      font-size:0.95rem;
    }
    table.sets th, table.sets td {
      border:1px solid rgba(0,0,0,0.08);
      padding:10px;
      vertical-align:top;
      background: #fff;
    }
    table.sets th {
      background: #eef3c8;
      color:#31572c;
      text-align:left;
      font-weight:700;
    }
    .math { color:#132a13; font-weight:600; }
    code.inline-math { font-family: "Times New Roman", serif; background:transparent; padding:0; }
    .example { margin:8px 0; padding:10px; background: var(--surface); border-radius:8px; border:1px solid rgba(19,42,19,0.04); }

    /* Linija prieš kiekvieną H2 antraštę */
h2 {
  position: relative;
  margin-top: 20px;
  padding-top: 20px;
  font-size: 1.5rem;
  color: #132a13;
}

h2::before {
  content: "";
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 1100px;
  height: 3px;
  background-color: #90a955;
}