/* =============================================================
   KN BASIC – base.css
   CSS custom properties, reset, typography, utilities
   ============================================================= */

/* ===== CUSTOM PROPERTIES ===== */
:root {
  --bg:          #f0f2f5;
  --bg2:         #e8eaee;
  --surface:     rgba(255,255,255,0.65);
  --surface2:    rgba(255,255,255,0.4);
  --border:      rgba(0,0,0,0.08);
  --border2:     rgba(0,180,120,0.3);
  --text:        #0d1117;
  --text2:       #3a4250;
  --text3:       #6b7280;
  --green:       #2d8b41;
  --green2:      #00e896;
  --green-dim:   rgba(0,192,122,0.15);
  --green-glow:  rgba(0,192,122,0.35);
  --blue:        #0077ff;
  --grid:        rgba(0,0,0,0.05);
  --shadow:      0 0.5rem 2rem rgba(0,0,0,0.10);
  --shadow-lg:   0 1.25rem 3.75rem rgba(0,0,0,0.15);
  --radius:      1rem;
  --radius-sm:   0.625rem;
  --mono:        'Space Mono', monospace;
  --sans:        'Outfit', sans-serif;
  --pcb-line:    rgba(0,192,122,0.18);
}

[data-theme="dark"] {
  --bg:         #0a0e16;
  --bg2:        #0f1522;
  --surface:    rgba(16,24,40,0.75);
  --surface2:   rgba(16,24,40,0.5);
  --border:     rgba(255,255,255,0.07);
  --border2:    rgba(0,192,122,0.4);
  --text:       #e8edf5;
  --text2:      #a8b4c8;
  --text3:      #607080;
  --grid:       rgba(0,232,150,0.04);
  --shadow:     0 0.5rem 2rem rgba(0,0,0,0.5);
  --shadow-lg:  0 1.25rem 3.75rem rgba(0,0,0,0.6);
  --pcb-line:   rgba(0,192,122,0.25);
}

/* ===== RESET ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html  { scroll-behavior: smooth; }
img, svg { display: block; max-width: 100%; }
a   { color: inherit; }
button { font-family: inherit; cursor: pointer; }

/* ===== BASE ===== */
body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  overflow-x: hidden;
  transition: background 0.4s, color 0.4s;
  line-height: 1.6;
}

/* Engineering grid background */
body::before {
  content: '';
  position: fixed; inset: 0; z-index: 0;
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 2.5rem 2.5rem;
  pointer-events: none;
}

/* PCB overlay */
#pcb-overlay {
  position: fixed; inset: 0; z-index: 1;
  pointer-events: none;
  opacity: 0.6;
}

/* ===== LAYOUT UTILITIES ===== */
section   { position: relative; z-index: 2; }
.container {
  max-width: 75rem;
  margin: 0 auto;
  padding: 0 2.5rem;
}

/* ===== GLASS CARDS ===== */
.glass {
  background: var(--surface);
  backdrop-filter: blur(1.25rem);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}
.glass-dark {
  background: var(--surface2);
  backdrop-filter: blur(1rem);
  border: 1px solid var(--border2);
  border-radius: var(--radius);
}

/* ===== SECTION TAG ===== */
.section-tag {
  display: inline-flex; align-items: center; gap: 0.5rem;
  font-family: var(--mono); font-size: 0.6875rem; font-weight: 700;
  color: var(--green); letter-spacing: 0.125rem;
  background: var(--green-dim); border: 1px solid var(--border2);
  padding: 0.3125rem 0.75rem;
  border-radius: 6.25rem;
  margin-bottom: 1rem;
}
.section-tag::before {
  content: ''; width: 0.375rem; height: 0.375rem;
  border-radius: 50%; background: var(--green);
  animation: pulse 2s infinite;
}

/* ===== BUTTONS ===== */
.btn-primary {
  display: inline-flex; align-items: center; gap: 0.5rem;
  background: linear-gradient(135deg, var(--green), #00a86b);
  color: #000; font-family: var(--mono); font-size: 0.8125rem; font-weight: 700;
  padding: 0.875rem 1.75rem; border-radius: 0.625rem;
  text-decoration: none; letter-spacing: 0.03125rem;
  transition: all 0.25s;
  box-shadow: 0 0.375rem 1.5rem var(--green-glow);
  border: none;
}
.btn-primary:hover  { transform: translateY(-0.125rem); box-shadow: 0 0.625rem 2rem var(--green-glow); }

.btn-secondary {
  display: inline-flex; align-items: center; gap: 0.5rem;
  background: var(--surface); backdrop-filter: blur(1rem);
  color: var(--text); font-family: var(--mono); font-size: 0.8125rem; font-weight: 700;
  padding: 0.875rem 1.75rem; border-radius: 0.625rem;
  text-decoration: none; border: 1px solid var(--border2);
  letter-spacing: 0.03125rem; transition: all 0.25s;
}
.btn-secondary:hover { border-color: var(--green); color: var(--green); transform: translateY(-0.125rem); }

/* ===== REVEAL ANIMATION ===== */
.reveal {
  opacity: 0;
  transform: translateY(1.875rem);
  transition: opacity 0.7s, transform 0.7s;
}
.reveal.visible { opacity: 1; transform: translateY(0); }

/* ===== KEYFRAMES ===== */
@keyframes pulse {
  0%,100% { opacity:1; transform:scale(1); }
  50%      { opacity:0.5; transform:scale(0.7); }
}

/* ===== RESPONSIVE ===== */
@media (max-width: 48rem) {
  .container { padding: 0 1.25rem; }
}