/* ===================================================
   MAIN.CSS — Shared design system for BlogBoard
   Theme: Deep Midnight — Studying & Reading Optimized
   =================================================== */

:root {
  /* Core Palette — Low-blue, eye-comfortable dark */
  --bg-deep: #0a0c14;
  --bg-surface: #0f1120;
  --bg-card: #131629;
  --bg-card-hover: #181d35;
  --bg-elevated: #1c2240;

  /* Accent Colors */
  --accent-primary: #7c6af7;
  --accent-primary-glow: rgba(124, 106, 247, 0.25);
  --accent-secondary: #4fc8b8;
  --accent-tertiary: #f7b96a;
  --accent-danger: #f76a6a;

  /* Text */
  --text-primary: #e8eaf6;
  --text-secondary: #9ba3c9;
  --text-muted: #5a637a;
  --text-accent: #a89cf7;

  /* Category Accent Colors */
  --cat-ml: #7c6af7;
  --cat-dl: #4fc8b8;
  --cat-nlp: #f7b96a;
  --cat-cv: #f76a6a;
  --cat-genai: #d06af7;
  --cat-ainews: #6ab4f7;
  --cat-statistics: #fb923c;

  /* Borders */
  --border: rgba(124, 106, 247, 0.12);
  --border-hover: rgba(124, 106, 247, 0.35);
  --border-card: rgba(255, 255, 255, 0.05);

  /* Typography */
  --font-sans: 'Inter', -apple-system, sans-serif;
  --font-serif: 'Playfair Display', Georgia, serif;
  --font-mono: 'Fira Code', 'Courier New', monospace;

  /* Spacing */
  --nav-height: 64px;
  --max-width: 1200px;
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-xl: 28px;

  /* Shadows */
  --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.4), 0 1px 4px rgba(0, 0, 0, 0.2);
  --shadow-glow: 0 0 40px rgba(124, 106, 247, 0.15);
  --shadow-nav: 0 1px 0 rgba(255, 255, 255, 0.05), 0 4px 24px rgba(0, 0, 0, 0.5);

  /* Transitions */
  --trans-fast: 0.15s ease;
  --trans-base: 0.25s ease;
  --trans-slow: 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ── Reset & Base ── */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  background: var(--bg-deep);
  color: var(--text-primary);
  font-family: var(--font-sans);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

img {
  max-width: 100%;
  display: block;
}

/* ── Ambient Background ── */
.ambient-bg {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  overflow: hidden;
}

.orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: 0.35;
  animation: orbDrift 20s ease-in-out infinite;
}

.orb-1 {
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, #3b2a8f 0%, transparent 70%);
  top: -200px;
  left: -150px;
  animation-delay: 0s;
}

.orb-2 {
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, #1a5555 0%, transparent 70%);
  bottom: -100px;
  right: -100px;
  animation-delay: -7s;
}

.orb-3 {
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, #4a1a6e 0%, transparent 70%);
  top: 50%;
  right: 20%;
  animation-delay: -14s;
}

@keyframes orbDrift {

  0%,
  100% {
    transform: translate(0, 0) scale(1);
  }

  33% {
    transform: translate(30px, -30px) scale(1.05);
  }

  66% {
    transform: translate(-20px, 20px) scale(0.95);
  }
}

.grid-overlay {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(124, 106, 247, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(124, 106, 247, 0.03) 1px, transparent 1px);
  background-size: 48px 48px;
}

#particleCanvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

/* ── Navigation ── */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-height);
  background: rgba(10, 12, 20, 0.8);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-card);
  box-shadow: var(--shadow-nav);
  transition: background var(--trans-base);
}

.navbar.scrolled {
  background: rgba(10, 12, 20, 0.95);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 1.2rem;
  letter-spacing: -0.02em;
  flex-shrink: 0;
}

.logo-icon {
  color: #03a57a;
  font-size: 1.4rem;
  line-height: 1;
}

.logo-text {
  color: var(--text-primary);
}

.logo-accent {
  color: var(--accent-primary);
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 4px;
  align-items: center;
}

.nav-link {
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--trans-fast), background var(--trans-fast);
}

.nav-link:hover,
.nav-link.active {
  color: var(--text-primary);
  background: rgba(124, 106, 247, 0.1);
}

.nav-link.active {
  color: var(--accent-primary);
}

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-secondary);
  border-radius: 2px;
  transition: all var(--trans-base);
}

/* ── Buttons ── */
.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  background: var(--accent-primary);
  color: white;
  font-weight: 600;
  font-size: 0.95rem;
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  transition: background var(--trans-fast), transform var(--trans-fast), box-shadow var(--trans-fast);
  box-shadow: 0 4px 20px rgba(124, 106, 247, 0.35);
}

.btn-primary:hover {
  background: #9178ff;
  transform: translateY(-1px);
  box-shadow: 0 8px 28px rgba(124, 106, 247, 0.45);
}

.btn-ghost {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 12px 24px;
  background: transparent;
  color: var(--text-secondary);
  font-weight: 500;
  font-size: 0.95rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  cursor: pointer;
  transition: color var(--trans-fast), border-color var(--trans-fast), background var(--trans-fast);
}

.btn-ghost:hover {
  color: var(--text-primary);
  border-color: var(--border-hover);
  background: rgba(124, 106, 247, 0.06);
}

.btn-ghost-sm {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 18px;
  background: transparent;
  color: var(--text-secondary);
  font-weight: 500;
  font-size: 0.85rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  cursor: pointer;
  transition: all var(--trans-fast);
}

.btn-ghost-sm:hover {
  color: var(--accent-primary);
  border-color: var(--border-hover);
}

/* ── Section Shared ── */
.section-header {
  text-align: center;
  margin-bottom: 56px;
}

.section-tag {
  display: inline-block;
  padding: 4px 14px;
  background: rgba(124, 106, 247, 0.12);
  color: var(--accent-primary);
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 12px;
}

.section-title {
  font-family: var(--font-serif);
  font-size: clamp(2rem, 4vw, 2.8rem);
  color: var(--text-primary);
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
}

.section-sub {
  font-size: 1rem;
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto;
  line-height: 1.7;
}

/* ── Gradient Text ── */
.gradient-text {
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ── Loading Spinner ── */
.loading-spinner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  padding: 60px 20px;
  color: var(--text-muted);
  font-size: 0.9rem;
}

.spinner {
  width: 36px;
  height: 36px;
  border: 3px solid rgba(124, 106, 247, 0.15);
  border-top-color: var(--accent-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* ── Footer ── */
.footer {
  position: relative;
  z-index: 10;
  margin-top: 80px;
  border-top: 1px solid var(--border-card);
  background: rgba(10, 12, 20, 0.8);
  backdrop-filter: blur(12px);
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 48px 24px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
  text-align: center;
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 1.1rem;
}

.footer-sub {
  color: var(--text-muted);
  font-size: 0.875rem;
}

.footer-cats {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
  justify-content: center;
}

.footer-cats a {
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 500;
  transition: color var(--trans-fast);
}

.footer-cats a:hover {
  color: var(--accent-primary);
}

.footer-copy {
  color: var(--text-muted);
  font-size: 0.8rem;
}

.footer-social {
  display: flex;
  gap: 16px;
  align-items: center;
  justify-content: center;
}

.social-link {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: 50%;
  background: rgba(124, 106, 247, 0.08);
  border: 1px solid var(--border-card);
  color: var(--text-muted);
  transition: color var(--trans-fast), background var(--trans-fast), border-color var(--trans-fast), transform var(--trans-fast);
}

.social-link:hover {
  color: var(--accent-primary);
  background: rgba(124, 106, 247, 0.15);
  border-color: var(--border-hover);
  transform: translateY(-2px);
}

/* ── Category Color Accents ── */
.accent-ml {
  --cat-color: var(--cat-ml);
}

.accent-dl {
  --cat-color: var(--cat-dl);
}

.accent-nlp {
  --cat-color: var(--cat-nlp);
}

.accent-cv {
  --cat-color: var(--cat-cv);
}

.accent-genai {
  --cat-color: var(--cat-genai);
}

.accent-ainews {
  --cat-color: var(--cat-ainews);
}

.accent-statistics {
  --cat-color: var(--cat-statistics);
}

/* ── Utility ── */
.hidden {
  display: none !important;
}

/* ── Responsive ── */
@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: rgba(10, 12, 20, 0.98);
    backdrop-filter: blur(20px);
    flex-direction: column;
    padding: 20px 24px;
    gap: 4px;
    border-bottom: 1px solid var(--border-card);
  }

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

  .nav-link {
    padding: 10px 14px;
    width: 100%;
  }

  .hamburger {
    display: flex;
  }

  .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);
  }
}