:root {
  --bg: #0f172a;
  --panel: #111827;
  --text: #e5e7eb;
  --muted: #9ca3af;
  --brand: #2563eb;
  --brand-2: #38bdf8;
  --card: #1f2937;
  --border: #374151;
}

/* Reset */
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
img { max-width: 100%; display: block; height: auto; }
a { text-decoration: none; color: inherit; }
button, input, textarea { font: inherit; }

body {
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  color: var(--text);
  background: linear-gradient(180deg, var(--bg), #0b1225 40%, #0a0f1f);
  line-height: 1.6;
}

.container { width: min(1100px, 92vw); margin-inline: auto; }

/* Skip link */
.skip-link { position: absolute; left: -9999px; }
.skip-link:focus {
  left: 0; background: #fff; color: #000;
  padding: 0.5rem 1rem; z-index: 1000;
}

/* Header */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(15,23,42,0.7);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: grid;
  grid-template-columns: 1fr auto auto;  /* desktop: brand | nav | (reserve) */
  align-items: center;
  padding: 0.9rem 0;
}
.brand { font-weight: 700; color: #fff; }

/* Nav */
.nav a { color: var(--muted); padding: 0.4rem 0.6rem; }
.nav a:hover, .nav a[aria-current="page"] {
  color: #fff; background: rgba(56,189,248,0.15); border-radius: 0.4rem;
}
.nav ul {
  display: flex; gap: 1rem;
  list-style: none; margin: 0; padding: 0;
}

.nav-toggle {
  display: none;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  padding: 0.35rem 0.6rem;
  cursor: pointer;
  color: var(--text);
}

.hidden { display: none; }
#more { display: none; } /* (if you use it anywhere) */

/* Hero */
.hero { padding: 3.5rem 0 2rem; }
.hero-inner {
  display: grid; gap: 2rem;
  grid-template-columns: 1fr clamp(280px, 35vw, 520px);
  align-items: center;
}
.hero h1 { font-size: clamp(1.8rem, 3vw + 0.5rem, 3rem); margin: 0 0 0.5rem; }
.hero p { color: var(--muted); margin: 0 0 1.25rem; }
.hero-cta { display: flex; gap: 0.75rem; flex-wrap: wrap; }

.btn {
  display: inline-block;
  padding: 0.7rem 1rem;
  border: 1px solid var(--border);
  border-radius: 0.6rem;
  background: #0b1225;
  color: var(--text);
  transition: 0.2s ease;
}
.btn:hover { transform: translateY(-1px); border-color: var(--brand-2); }
.btn.primary {
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
  border-color: transparent; color: #071019; font-weight: 700;
}
.btn.small { padding: 0.5rem 0.75rem; font-size: 0.95rem; }

.hero-media {
  border-radius: 0.8rem; overflow: hidden;
  border: 1px solid var(--border);
  box-shadow: 0 10px 24px rgba(0,0,0,0.25);
}
.hero-media img {
  aspect-ratio: 4 / 3; object-fit: cover;
}

/* Courses grid & cards */
.courses { padding: 2rem 0 2.5rem; }
.grid {
  display: grid; gap: 1.25rem;
  grid-template-columns: repeat(3, minmax(0, 1fr));
}
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 0.8rem;
  overflow: hidden;
  box-shadow: 0 10px 24px rgba(0,0,0,0.25);
}
.card-body { padding: 1rem 1rem 1.2rem; }
.card h3 { margin: 0 0 0.25rem; }
.card p { color: var(--muted); margin: 0 0 0.75rem; }

/* Box model demo (if used somewhere) */
#one-value { border: ridge #cccccc; border-width: 6px; }
#two-values { border: solid red; border-width: 2px 10px; }
#three-values { border: dotted orange; border-width: 0.3em 0 9px; }
#four-values { border: solid lightgreen; border-width: thin medium thick 1em; }

/* Slideshow */
.slideshow-container { position: relative; }
.myslide { display: none; }
.myslide.active { display: block; }
.fade { animation: fadein 400ms ease-in; }
@keyframes fadein { from {opacity: 0;} to {opacity: 1;} }
.text { text-align: center; }

/* Kontakt */
.contact {
  padding: 2.25rem 0 2.75rem;
  border-top: 1px solid var(--border);
}
.contact-form { display: grid; gap: 0.9rem; max-width: 640px; }
.field { display: grid; gap: 0.35rem; }
input, textarea {
  background: #0c142a; color: var(--text);
  border: 1px solid var(--border);
  border-radius: 0.6rem; padding: 0.7rem 0.8rem;
}
input:focus, textarea:focus {
  outline: 2px solid var(--brand-2); outline-offset: 2px;
}

/* Footer */
.site-footer { border-top: 1px solid var(--border); display: flex; justify-content: center; }
.site-footer .container { padding: 1.3rem 0; color: var(--muted); }

/* Screen reader only */
.sr-only {
  position: absolute !important;
  width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0, 0, 0, 0);
  white-space: nowrap; border: 0;
}

/* Responsive */
@media (max-width: 900px) {
  .hero-inner { grid-template-columns: 1fr; }
  .grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 720px) {
  /* Header becomes brand | toggle, and nav gets its own row */
  .header-inner { grid-template-columns: 1fr auto; padding: 0.7rem 0; }
  .nav-toggle { display: inline-block; }

  .nav {
    display: none;              /* hidden by default on mobile */
    grid-column: 1 / -1;        /* make nav span full width */
    margin-top: 0.5rem;
  }
  .nav.open { display: block; }

  .nav ul { flex-direction: column; gap: 0.5rem; padding: 0.5rem 0; }
  .nav a {
    display: block; padding: 0.8rem 0.9rem;
    background: rgba(56,189,248,0.10);
    border: 1px solid var(--border);
    border-radius: 0.5rem;
  }

  /* Optional: simpler hero image framing on very small screens */
  .hero-media img { box-shadow: none; }
  .grid { grid-template-columns: 1fr; }
}