/* =========================
   RESET & BASE
========================= */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* zabrání bílé při overscrollu */
html, body {
  width: 100%;
  min-height: 100%;
  background-color: #0b0f1a;
}

/* smooth scroll */
html {
  scroll-behavior: smooth;
}

/* =========================
   THEME
========================= */
:root{
  --text: #eaeaea;
  --muted: rgba(234,234,234,0.72);
  --card: rgba(255,255,255,0.04);
  --border: rgba(255,255,255,0.10);
  --shadow: 0 22px 70px rgba(0,0,0,0.55);
  --accent: linear-gradient(90deg, #a050ff, #50b4ff);
  --accent-a: rgba(160,80,255,0.55);
  --accent-b: rgba(80,180,255,0.35);
}

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.6;
  color: var(--text);

  min-height: 100vh;
  overflow-x: hidden;

  background: radial-gradient(
    1200px 600px at 20% 10%,
    #1b1f2a 0%,
    #0b0f1a 60%
  );

  position: relative; /* pro pseudo-elementy */
}

/* =========================
   STARFIELD / GALAXY BACKGROUND
========================= */
body::before{
  content:"";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: -2;

  background:
    radial-gradient(1px 1px at 10% 20%, rgba(255,255,255,0.9) 99%, transparent 100%),
    radial-gradient(1px 1px at 30% 80%, rgba(255,255,255,0.7) 99%, transparent 100%),
    radial-gradient(1px 1px at 70% 30%, rgba(255,255,255,0.8) 99%, transparent 100%),
    radial-gradient(1px 1px at 90% 60%, rgba(255,255,255,0.6) 99%, transparent 100%),
    radial-gradient(2px 2px at 40% 40%, rgba(255,255,255,0.55) 99%, transparent 100%),
    radial-gradient(2px 2px at 80% 10%, rgba(255,255,255,0.45) 99%, transparent 100%);

  background-size:
    700px 700px,
    900px 900px,
    800px 800px,
    1100px 1100px,
    1200px 1200px,
    1400px 1400px;

  opacity: 0.45;
}

body::after{
  content:"";
  position: fixed;
  inset: -20%;
  pointer-events: none;
  z-index: -1;

  background:
    radial-gradient(600px 320px at 20% 15%, rgba(160,80,255,0.18), transparent 60%),
    radial-gradient(700px 380px at 75% 25%, rgba(80,180,255,0.16), transparent 60%),
    radial-gradient(900px 520px at 55% 80%, rgba(255,255,255,0.05), transparent 65%);

  filter: blur(18px);
  opacity: 0.9;
}

/* =========================
   CONTAINER
========================= */
.container{
  max-width: 1100px;
  margin: 0 auto;
  padding: 1.5rem;
}

/* =========================
   LAYOUT
========================= */
main { padding-top: 3rem; }

/* =========================
   HEADER & NAV (DESKTOP DEFAULT)
========================= */
header{
  position: sticky;
  top: 0;
  z-index: 10;

  background: rgba(10,12,20,0.55);
  border: 1px solid var(--border);
  border-radius: 18px;
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow);

  padding: 1rem 1.25rem;
  margin-top: 1rem;
}

.header-inner{
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
}

header h1{
  font-size: 1.4rem;
  font-weight: 600;
  background: var(--accent);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  text-shadow: 0 0 18px rgba(80,180,255,0.12);
}

.nav-toggle{
  display: none; /* desktop hidden */
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: rgba(255,255,255,0.03);
  color: var(--text);
  cursor: pointer;
}

.nav { display: block; }

nav ul{
  list-style: none;
  display: flex;
  gap: 1.2rem;
  align-items: center;
}

nav a,
nav a:visited{
  text-decoration: none;
  color: var(--text);
  font-size: 0.95rem;
  font-weight: 500;
  padding: 0.45rem 0.75rem;
  border-radius: 999px;
  position: relative;
}

nav a:hover{ background: rgba(255,255,255,0.08); }

nav a:focus{
  outline: 2px solid rgba(255,255,255,0.6);
  outline-offset: 4px;
}

nav a::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: -6px;
  width: 0;
  height: 2px;
  background: var(--accent);
  border-radius: 999px;
  transition: width 0.25s ease, left 0.25s ease;
}

nav a:hover::after {
  width: 70%;
  left: 15%;
}

.github-btn{
  border: 1px solid rgba(80,180,255,0.45);
  padding: 0.45rem 0.9rem;
  border-radius: 999px;

  background: linear-gradient(90deg, rgba(80,180,255,0.18), rgba(160,80,255,0.18));
  color: var(--text);
  position: relative;
  overflow: hidden;

  transition: background 0.2s ease, box-shadow 0.2s ease, transform 0.15s ease;
}

.github-btn:hover{
  background: linear-gradient(90deg, rgba(80,180,255,0.35), rgba(160,80,255,0.35));
  box-shadow: 0 0 22px rgba(80,180,255,0.35);
  transform: translateY(-1px);
}

.github-btn::after{
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 999px;
  background:
    radial-gradient(120px 40px at 30% 50%, var(--accent-a), transparent 70%),
    radial-gradient(120px 40px at 70% 50%, var(--accent-b), transparent 70%);
  opacity: 0;
  transition: opacity 0.2s ease;
  pointer-events: none;
}

.github-btn:hover::after{ opacity: 1; }

/* =========================
   SECTIONS
========================= */
section{
  scroll-margin-top: 110px;
  padding: 4rem 0;
  background: transparent;
}

section h2{
  font-size: 2rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 1rem;
}

/* =========================
   HERO
========================= */
#hero{
  padding: 3rem 2rem;
  margin-top: 1.5rem;

  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 18px;
  backdrop-filter: blur(10px);

  text-align: center;
}

#hero h2{
  font-size: 2.6rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 0.75rem;

  background: var(--accent);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;

  text-shadow:
    0 0 14px rgba(80,180,255,0.35),
    0 0 32px rgba(160,80,255,0.18);
}

#hero p{
  max-width: 60ch;
  margin: 0.75rem auto 0;
  color: var(--muted);
}

/* =========================
   ABOUT
========================= */
#about{ text-align: center; }

#about p{
  max-width: 65ch;
  margin: 0 auto 1.6rem auto;
  font-size: 1.05rem;
  line-height: 1.75;
  color: var(--muted);
}

/* =========================
   SKILLS
========================= */
#skills{ text-align: center; }

#skills ul{
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.9rem;
  max-width: 900px;
  margin: 0 auto;
  padding: 0;
}

#skills li{
  position: relative;
  overflow: hidden;

  border-radius: 999px;
  padding: 0.45rem 0.9rem;

  background: var(--card);
  border: 1px solid var(--border);
  backdrop-filter: blur(10px);

  color: var(--text);
  font-size: 0.9rem;

  transition: transform 0.15s ease;
}

#skills li::before{
  content: "";
  position: absolute;
  inset: 0;
  padding: 1px;
  border-radius: 999px;

  background: linear-gradient(135deg, var(--accent-a), var(--accent-b), rgba(255,255,255,0.10));

  -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
  mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);

  -webkit-mask-composite: xor;
  mask-composite: exclude;

  opacity: 0.55;
  pointer-events: none;
}

#skills li:hover{ transform: translateY(-1px); }

/* =========================
   PROJECTS
========================= */
#projects .projects-grid{
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem;
}

.project-card{
  position: relative;
  overflow: hidden;

  border: 1px solid var(--border);
  padding: 1.25rem;
  border-radius: 16px;
  background: var(--card);
  backdrop-filter: blur(10px);

  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.project-card::before{
  content: "";
  position: absolute;
  inset: 0;
  padding: 1px;
  border-radius: 16px;

  background: linear-gradient(135deg, var(--accent-a), var(--accent-b), rgba(255,255,255,0.10));

  -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
  mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);

  -webkit-mask-composite: xor;
  mask-composite: exclude;

  opacity: 0.6;
  pointer-events: none;
}

.project-card:hover::before{ opacity: 0.8; }

.project-card:hover{
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.project-head{
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 0.75rem;
}

.project-card h3{
  font-weight: 700;
  margin: 0;

  background: var(--accent);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;

  text-shadow:
    0 0 12px rgba(80,180,255,0.28),
    0 0 26px rgba(160,80,255,0.14);
}

.project-card p{
  color: var(--muted);
  margin-top: 0.25rem;
}

.project-links{
  display: flex;
  gap: 0.6rem;
}

.project-links a,
.project-links a:visited{
  text-decoration: none;
  color: var(--text);
  font-size: 0.9rem;
  padding: 0.35rem 0.6rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: rgba(255,255,255,0.03);
}

.project-links a:hover{ background: rgba(255,255,255,0.08); }

.project-tags{
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1rem;
  padding: 0;
}

.project-tags li{
  border: 1px solid var(--border);
  padding: 0.35rem 0.6rem;
  border-radius: 999px;
  background: rgba(255,255,255,0.03);
  color: var(--muted);
  font-size: 0.85rem;
}

/* =========================
   CONTACT
========================= */
#contact h2{
  font-size: 2rem;
  margin-bottom: 2rem;
}

.contact-grid{
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
}

.contact-card{
  position: relative;
  overflow: hidden;
  padding: 1.5rem;
  border-radius: 18px;

  text-decoration: none;
  color: var(--text);

  background: var(--card);
  border: 1px solid var(--border);
  backdrop-filter: blur(10px);

  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
}

.contact-card::before{
  content: "";
  position: absolute;
  inset: 0;
  padding: 1px;
  border-radius: 18px;

  background: linear-gradient(135deg, var(--accent-a), var(--accent-b), rgba(255,255,255,0.10));

  -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
  mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);

  -webkit-mask-composite: xor;
  mask-composite: exclude;

  opacity: 0.6;
  pointer-events: none;
}

.contact-card:hover::before{ opacity: 0.8; }

.contact-title{
  font-size: 1.05rem;
  font-weight: 600;
}

.contact-sub{
  font-size: 0.9rem;
  color: var(--muted);
}

.contact-card:hover{
  transform: translateY(-4px);
  background: rgba(255,255,255,0.07);
  box-shadow: var(--shadow);
}

/* =========================
   LEARNING / EDUCATION
========================= */
#learning-education h2{ text-align: center; }

#learning-education ul{
  max-width: 60ch;
  margin: 1.5rem auto 0;
  padding-left: 1.2rem;
  text-align: left;
}

#learning-education li{
  margin: 0.6rem 0;
  color: var(--text);
}

/* =========================
   FOOTER
========================= */
footer{
  border-top: 1px solid rgba(255,255,255,0.10);
  margin-top: 4rem;
  padding: 2rem 0;
  font-size: 0.9rem;
  color: var(--muted);
  text-align: center;
}

/* =========================
   RESPONSIVE (MOBILE)
========================= */
@media (max-width: 768px){
  header{
    top: env(safe-area-inset-top);
    z-index: 1000;
  }

  .header-inner{
    flex-wrap: wrap;
  }

  .nav-toggle{
    display: inline-flex;
  }

  .nav{
    display: none;
    width: 100%;
    margin-top: 0.75rem;
  }

  header.nav-open .nav{
    display: flex;
  }

  nav ul{
    width: 100%;
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }

  section{ padding: 3rem 0; }

  .container{ padding: 1rem; }

  #hero{ padding: 2rem 1rem; }

  #hero h2{ font-size: 2rem; }

  #skills ul,
  .projects-grid,
  .contact-grid{ gap: 1rem; }
}