@import url('https://fonts.googleapis.com/css2?family=Syne:wght@400;600;700;800&family=JetBrains+Mono:wght@300;400;500;700&display=swap');

:root {
  --bg: #080b12;
  --bg2: #0e1220;
  --bg3: #141929;
  --surface: #1a2035;
  --border: #252d45;
  --text: #c8d3f5;
  --muted: #607080;
  --accent-html: #ff7b54;
  --accent-css: #38d9f5;
  --accent-js: #f5d761;
  --accent-active: #a78bfa;
  --white: #eef2ff;
  --radius: 12px;
  --radius-sm: 6px;
  --font-body: 'Syne', sans-serif;
  --font-code: 'JetBrains Mono', monospace;
  --nav-h: 68px;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  min-height: 100vh;
}

/* ── NAV ── */
nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  height: var(--nav-h);
  background: rgba(8, 11, 18, 0.85);
  backdrop-filter: blur(18px);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 2.5rem;
}

.nav-logo {
  font-family: var(--font-code);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--white);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.nav-logo span { color: var(--accent-active); }

.nav-links {
  display: flex;
  gap: 0.25rem;
  list-style: none;
}

.nav-links a {
  text-decoration: none;
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 600;
  padding: 0.45rem 1rem;
  border-radius: var(--radius-sm);
  transition: all 0.2s;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  border: 1px solid transparent;
}
.nav-links a:hover { color: var(--white); background: var(--surface); }
.nav-links a.html-link { color: var(--accent-html); }
.nav-links a.css-link  { color: var(--accent-css); }
.nav-links a.js-link   { color: var(--accent-js); }
.nav-links a.html-link:hover { border-color: var(--accent-html); background: rgba(255,123,84,.08); }
.nav-links a.css-link:hover  { border-color: var(--accent-css);  background: rgba(56,217,245,.08); }
.nav-links a.js-link:hover   { border-color: var(--accent-js);   background: rgba(245,215,97,.08); }
.nav-links a.active-page { color: var(--white); background: var(--surface); border-color: var(--border); }

/* Hamburger */
.hamburger { display: none; flex-direction: column; gap: 5px; cursor: pointer; background: none; border: none; padding: 4px; }
.hamburger span { width: 22px; height: 2px; background: var(--text); border-radius: 2px; transition: all 0.3s; display: block; }
.hamburger.open span:nth-child(1) { transform: rotate(45deg) translate(5px,5px); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { transform: rotate(-45deg) translate(5px,-5px); }

/* Mobile menu */
.mobile-menu {
  display: none;
  position: fixed;
  top: var(--nav-h); left: 0; right: 0;
  background: var(--bg2);
  border-bottom: 1px solid var(--border);
  padding: 1rem 2rem 1.5rem;
  z-index: 99;
  flex-direction: column;
  gap: 0.5rem;
}
.mobile-menu.open { display: flex; }
.mobile-menu a {
  text-decoration: none;
  color: var(--text);
  font-weight: 600;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  transition: all 0.2s;
}

/* ── LAYOUT ── */
.page-wrap {
  max-width: 960px;
  margin: 0 auto;
  padding: calc(var(--nav-h) + 3rem) 2rem 5rem;
}

/* ── HEADINGS ── */
h1 { font-size: clamp(2rem, 5vw, 3.2rem); font-weight: 800; color: var(--white); line-height: 1.1; }
h2 { font-size: 1.6rem; font-weight: 700; color: var(--white); margin: 3rem 0 1rem; }
h3 { font-size: 1.15rem; font-weight: 600; color: var(--white); margin: 2rem 0 0.75rem; }
p  { color: var(--text); margin-bottom: 1rem; }

/* ── BADGES & PILLS ── */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-family: var(--font-code);
  font-size: 0.72rem;
  font-weight: 700;
  padding: 0.3rem 0.75rem;
  border-radius: 100px;
  border: 1px solid;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.badge-html { color: var(--accent-html); border-color: rgba(255,123,84,.35); background: rgba(255,123,84,.08); }
.badge-css  { color: var(--accent-css);  border-color: rgba(56,217,245,.35);  background: rgba(56,217,245,.08); }
.badge-js   { color: var(--accent-js);   border-color: rgba(245,215,97,.35);   background: rgba(245,215,97,.08); }

/* ── HERO (index) ── */
.hero {
  min-height: calc(100vh - var(--nav-h));
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: calc(var(--nav-h) + 1rem) 2rem 4rem;
  max-width: 960px;
  margin: 0 auto;
}
.hero-eyebrow {
  font-family: var(--font-code);
  font-size: 0.8rem;
  color: var(--accent-active);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: 1.25rem;
}
.hero h1 { margin-bottom: 1.25rem; }
.hero h1 em { font-style: normal; color: var(--accent-active); }
.hero-sub {
  font-size: 1.05rem;
  color: var(--muted);
  max-width: 500px;
  margin-bottom: 3rem;
}

/* Card grid */
.card-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.25rem;
  margin-top: 1.5rem;
}
.card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem;
  text-decoration: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: all 0.25s;
  position: relative;
  overflow: hidden;
}
.card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
}
.card-html::before { background: var(--accent-html); }
.card-css::before  { background: var(--accent-css); }
.card-js::before   { background: var(--accent-js); }
.card:hover { transform: translateY(-3px); background: var(--bg3); border-color: var(--surface); }
.card-icon { font-size: 2rem; }
.card-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--white);
}
.card-html .card-title { color: var(--accent-html); }
.card-css  .card-title { color: var(--accent-css); }
.card-js   .card-title { color: var(--accent-js); }
.card-desc { font-size: 0.88rem; color: var(--muted); line-height: 1.6; }
.card-arrow { margin-top: auto; font-size: 0.85rem; color: var(--muted); display: flex; align-items: center; gap: 0.3rem; transition: gap 0.2s; }
.card:hover .card-arrow { gap: 0.6rem; }

/* ── PAGE HERO ── */
.page-hero {
  padding: 2.5rem 0 3rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 3rem;
}
.page-hero h1 { margin: 0.75rem 0 1rem; }
.page-hero p { color: var(--muted); font-size: 1rem; max-width: 600px; }

/* ── CODE BLOCKS ── */
pre {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  overflow-x: auto;
  margin: 1rem 0 1.5rem;
  position: relative;
}
code {
  font-family: var(--font-code);
  font-size: 0.875rem;
  line-height: 1.75;
  color: var(--text);
}
.code-label {
  position: absolute;
  top: 0.6rem; right: 0.8rem;
  font-family: var(--font-code);
  font-size: 0.65rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

/* Syntax colors */
.k  { color: #c792ea; } /* keyword */
.s  { color: #c3e88d; } /* string */
.c  { color: var(--muted); font-style: italic; } /* comment */
.t  { color: var(--accent-css); }  /* tag */
.a  { color: var(--accent-js); }   /* attr */
.v  { color: #f78c6c; }  /* value */
.fn { color: #82aaff; }  /* function */
.n  { color: var(--accent-html); } /* number/special */

/* ── SECTIONS ── */
.section {
  margin-bottom: 3.5rem;
}
.section-divider {
  border: none;
  border-top: 1px solid var(--border);
  margin: 3rem 0;
}

/* Tag reference grid */
.tag-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 0.75rem;
  margin: 1rem 0;
}
.tag-item {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.9rem 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}
.tag-name {
  font-family: var(--font-code);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--accent-html);
}
.css-prop-name { color: var(--accent-css) !important; }
.js-keyword-name { color: var(--accent-js) !important; }
.tag-desc { font-size: 0.8rem; color: var(--muted); }

/* ── EXERCISES ── */
.exercise-box {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin: 1.5rem 0;
}
.exercise-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
}
.exercise-title {
  font-weight: 700;
  font-size: 0.9rem;
  color: var(--white);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.exercise-body { padding: 1.5rem; }

textarea.code-input {
  width: 100%;
  min-height: 160px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text);
  font-family: var(--font-code);
  font-size: 0.82rem;
  padding: 1rem;
  resize: vertical;
  outline: none;
  transition: border-color 0.2s;
  line-height: 1.7;
}
textarea.code-input:focus { border-color: var(--accent-active); }

.preview-frame {
  width: 100%;
  min-height: 160px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.55rem 1.25rem;
  border-radius: var(--radius-sm);
  font-family: var(--font-body);
  font-size: 0.85rem;
  font-weight: 700;
  cursor: pointer;
  border: 1px solid;
  transition: all 0.2s;
}
.btn-html { background: rgba(255,123,84,.12); border-color: rgba(255,123,84,.4); color: var(--accent-html); }
.btn-css  { background: rgba(56,217,245,.12);  border-color: rgba(56,217,245,.4);  color: var(--accent-css); }
.btn-js   { background: rgba(245,215,97,.12);   border-color: rgba(245,215,97,.4);   color: var(--accent-js); }
.btn:hover { filter: brightness(1.2); transform: translateY(-1px); }

/* Two column layout */
.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

/* ── TASKS ── */
.task-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin: 1rem 0;
}
.task-item {
  display: flex;
  gap: 1rem;
  align-items: flex-start;
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  transition: border-color 0.2s;
}
.task-item:hover { border-color: var(--surface); }
.task-num {
  font-family: var(--font-code);
  font-size: 0.8rem;
  font-weight: 700;
  min-width: 2rem;
  height: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  border: 1px solid;
  flex-shrink: 0;
}
.task-html .task-num { color: var(--accent-html); border-color: rgba(255,123,84,.35); background: rgba(255,123,84,.08); }
.task-css  .task-num { color: var(--accent-css);  border-color: rgba(56,217,245,.35);  background: rgba(56,217,245,.08); }
.task-js   .task-num { color: var(--accent-js);   border-color: rgba(245,215,97,.35);   background: rgba(245,215,97,.08); }
.task-content { flex: 1; }
.task-content strong { display: block; color: var(--white); font-size: 0.95rem; margin-bottom: 0.35rem; }
.task-content p { font-size: 0.85rem; color: var(--muted); margin: 0; }
.task-diff {
  font-family: var(--font-code);
  font-size: 0.65rem;
  font-weight: 700;
  padding: 0.2rem 0.5rem;
  border-radius: 100px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  flex-shrink: 0;
}
.diff-easy   { background: rgba(68,235,154,.1); color: #44eb9a; border: 1px solid rgba(68,235,154,.25); }
.diff-medium { background: rgba(245,215,97,.1);  color: var(--accent-js); border: 1px solid rgba(245,215,97,.25); }
.diff-hard   { background: rgba(255,123,84,.1);  color: var(--accent-html); border: 1px solid rgba(255,123,84,.25); }

/* ── INFO CARDS ── */
.info-card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin: 1rem 0;
  display: flex;
  gap: 1rem;
}
.info-icon { font-size: 1.5rem; flex-shrink: 0; }
.info-content h4 { color: var(--white); font-size: 0.95rem; margin-bottom: 0.4rem; }
.info-content p { font-size: 0.85rem; color: var(--muted); margin: 0; }

/* ── RESULT ── */
#result-output {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 1rem;
  font-family: var(--font-code);
  font-size: 0.82rem;
  min-height: 60px;
  color: var(--text);
  white-space: pre-wrap;
  margin-top: 0.75rem;
}

/* ── FOOTER NAV ── */
.page-nav-footer {
  display: flex;
  justify-content: space-between;
  padding: 2rem 0;
  border-top: 1px solid var(--border);
  margin-top: 4rem;
  gap: 1rem;
}
.pnf-link {
  text-decoration: none;
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}
.pnf-label { font-size: 0.75rem; color: var(--muted); text-transform: uppercase; letter-spacing: 0.08em; }
.pnf-title { font-size: 1rem; font-weight: 700; color: var(--white); transition: color 0.2s; }
.pnf-link:hover .pnf-title { color: var(--accent-active); }
.pnf-link.right { text-align: right; }

/* ── SELECTOR DEMO ── */
.color-swatch {
  display: inline-block;
  width: 20px; height: 20px;
  border-radius: 4px;
  vertical-align: middle;
  margin-right: 6px;
  border: 1px solid rgba(255,255,255,.1);
}

/* ── RESPONSIVE ── */
@media (max-width: 720px) {
  nav { padding: 0 1.25rem; }
  .nav-links { display: none; }
  .hamburger { display: flex; }
  .card-grid { grid-template-columns: 1fr; }
  .two-col { grid-template-columns: 1fr; }
  .page-wrap { padding: calc(var(--nav-h) + 1.5rem) 1.25rem 4rem; }
  .hero { padding: calc(var(--nav-h) + 1rem) 1.25rem 3rem; }
  .page-nav-footer { flex-direction: column; }
}