@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@600;700&family=Roboto:wght@400;500&display=swap');
html { 
  scroll-behavior: smooth; 
}
:root {
  --color-primary: #4a90e2;
  --color-primary-dark: #357abd;
  --color-accent: #f5a623;
  --color-bg: #f0f4f8;
  --color-text: #212b36;
  --color-text-light: #617d98;
  --font-heading: 'Poppins', sans-serif;
  --font-body: 'Roboto', sans-serif;
  --spacing: 1rem;
  --radius: 14px;
  --shadow-light: rgba(0, 0, 0, 0.07);
  --shadow-md: rgba(0, 0, 0, 0.15);
  --transition-speed: 0.4s;
}

/* Reset & base */
*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0 auto;
  padding: 0 var(--spacing);
  font-family: var(--font-body);
  font-weight: 400;
  font-size: 1rem;
  line-height: 1.65;
  color: var(--color-text);
  background: var(--color-bg);
  max-width: 960px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}
/* DARK MODE STYLES */
body.dark-mode {
  background-color: #121212;
  color: #e0e0e0; /* lighter text for general body */
}

/* Make sure all main containers and their text update in dark mode */
body.dark-mode header,
body.dark-mode footer,
body.dark-mode nav,
body.dark-mode main,
body.dark-mode article,
body.dark-mode section {
  background-color: #1f1f1f;
  color: #e0e0e0;
}

/* Links in dark mode */
body.dark-mode a {
  color: #80b3ff;
}

body.dark-mode a:hover,
body.dark-mode a:focus {
  color: #cce5ff;
}

/* Header and Footer text color */
header.dark-mode,
footer.dark-mode {
  background-color: #1f1f1f;
  color: #e0e0e0;
}

/* Navbar links */
nav ul li a {
  color: #f0f4f8dd;
  transition: border-color var(--transition-speed) ease, color var(--transition-speed) ease;
}

body.dark-mode nav ul li a {
  color: #a2d2ff;
}

body.dark-mode nav ul li a:hover,
body.dark-mode nav ul li a:focus {
  color: #cce5ff;
  border-bottom-color: var(--color-accent);
}

/* Buttons */
button#dark-mode-toggle {
  margin-left: 10px;
  padding: 5px 10px;
  cursor: pointer;
  background-color: transparent;
  border: 2px solid var(--color-primary);
  border-radius: 5px;
  color: var(--color-primary);
  font-size: 1rem;
  transition: background-color 0.3s, color 0.3s;
}

button#dark-mode-toggle:hover {
  background-color: var(--color-primary);
  color: white;
}

/* Main content styling */
main {
  background: #fff;
  padding: 3rem 3.5rem;
  border-radius: var(--radius);
  box-shadow: 0 14px 45px var(--shadow-light);
  transition: box-shadow 0.3s ease;
  color: var(--color-text);
}

body.dark-mode main {
  background-color: #222222;
  box-shadow: 0 14px 45px rgba(0,0,0,0.6);
  color: #e0e0e0;
}

/* Hero section */
.hero h2 {
  color: var(--color-primary-dark);
}

body.dark-mode .hero h2 {
  color: #8ab4f8;
}

.hero p {
  color: var(--color-text-light);
}

body.dark-mode .hero p {
  color: #bbb;
}

/* Articles section */
.articles h3 {
  color: var(--color-primary-dark);
  border-bottom: 4px solid var(--color-accent);
}

body.dark-mode .articles h3 {
  color: #8ab4f8;
  border-color: #f5a623;
}

.articles li {
  background: #fafafa;
  color: var(--color-primary-dark);
  box-shadow: 0 10px 25px rgba(74, 144, 226, 0.15);
}

body.dark-mode .articles li {
  background: #2a2a2a;
  color: #cfdcff;
  box-shadow: 0 10px 25px rgba(245, 166, 35, 0.3);
}

/* Article content */
article {
  color: var(--color-text);
}

body.dark-mode article {
  color: #e0e0e0;
}

article em {
  color: var(--color-text-light);
}

body.dark-mode article em {
  color: #bbb;
}

article table {
  background-color: #f7f9fc;
  color: var(--color-text);
}

body.dark-mode article table {
  background-color: #2a2a2a;
  color: #e0e0e0;
  border-color: #555;
}

article th,
article td {
  border: 1px solid #ddd;
}

body.dark-mode article th,
body.dark-mode article td {
  border-color: #555;
}

article code {
  background-color: #f0f4f8;
  color: #212b36;
}

body.dark-mode article code {
  background-color: #333;
  color: #ddd;
}

/* Headings fade-in */
h1, h2, h3 {
  color: var(--color-text);
}

body.dark-mode h1,
body.dark-mode h2,
body.dark-mode h3 {
  color: #e0e0e0;
}

/* Footer */
footer {
  text-align: center;
  padding: 3rem 1rem;
  font-size: 0.95rem;
  color: var(--color-text-light);
  letter-spacing: 0.1em;
  border-top: 2px solid #eee;
  margin-top: 5rem;
  user-select: none;
}

body.dark-mode footer {
  border-top-color: #444;
  color: #bbb;
}

/* Transitions for smooth color changes */
body, header, footer, nav, main, article, a, button {
  transition: background-color 0.4s ease, color 0.4s ease;
}

/* Headings with fade-in */
h1, h2, h3 {
  font-family: var(--font-heading);
  font-weight: 700;
  letter-spacing: 0.05em;
  margin-bottom: 0.6rem;
  opacity: 0;
  animation: fadeInUp 0.7s forwards;
}

h1 { font-size: 3rem; animation-delay: 0.1s;}
h2 { font-size: 2.25rem; animation-delay: 0.3s;}
h3 { font-size: 1.6rem; animation-delay: 0.5s;}

/* Fade in animation */
@keyframes fadeInUp {
  to {
    opacity: 1;
    transform: translateY(0);
  }
  from {
    opacity: 0;
    transform: translateY(20px);
  }
}

/* Header with glassy gradient background */
header {
  position: sticky;
  top: 0;
  background: linear-gradient(135deg, #6a9ef8cc 0%, #4a90e2cc 100%);
  backdrop-filter: saturate(200%) blur(16px);
  box-shadow: 0 8px 32px var(--shadow-md);
  z-index: 9999;
  padding: 1rem 0;
  margin-bottom: 3rem;
  border-radius: 0 0 var(--radius) var(--radius);
  user-select: none;
}

/* Site title */
header h1 {
  text-align: center;
  margin: 0;
  font-size: 3rem;
  color: #fff;
  text-shadow: 0 2px 6px rgba(0,0,0,0.3);
  letter-spacing: 0.1em;
  cursor: default;
  font-weight: 800;
}

/* Navbar styling */
nav ul {
  list-style: none;
  padding: 0;
  margin: 1rem 0 0 0;
  display: flex;
  justify-content: center;
  gap: 1.5rem;
}

nav ul li {
  margin: 0;
  padding: 0;
}

nav ul li a {
  display: inline-block;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  padding: 0.3rem 0;
  color: #f0f4f8dd;
  font-weight: 700;
  font-size: 1.15rem;
  text-decoration: none;
  border-bottom: 3px solid transparent;
  transition: border-color var(--transition-speed) ease, color var(--transition-speed) ease;
  cursor: pointer;
}

nav ul li a:hover,
nav ul li a:focus {
  border-bottom-color: var(--color-accent);
  color: #fff;
  outline: none;
}

/* Main content styling */
main {
  background: #fff;
  padding: 3rem 3.5rem;
  border-radius: var(--radius);
  box-shadow: 0 14px 45px var(--shadow-light);
  transition: box-shadow 0.3s ease;
}

main:hover {
  box-shadow: 0 20px 60px rgba(0,0,0,0.15);
}

/* Hero section */
.hero {
  text-align: center;
  margin-bottom: 4rem;
}

.hero h2 {
  font-size: 3.5rem;
  font-weight: 800;
  margin-bottom: 1rem;
  color: var(--color-primary-dark);
  letter-spacing: 0.1em;
  animation: fadeInUp 1s ease forwards;
}

.hero p {
  font-size: 1.35rem;
  color: var(--color-text-light);
  max-width: 700px;
  margin: 0 auto;
  font-weight: 500;
  line-height: 1.6;
  animation: fadeInUp 1.2s ease forwards;
}

/* Articles */
.articles h3 {
  font-size: 2.5rem;
  margin-bottom: 2rem;
  color: var(--color-primary-dark);
  border-bottom: 4px solid var(--color-accent);
  padding-bottom: 0.5rem;
  max-width: fit-content;
  margin-left: auto;
  margin-right: auto;
  letter-spacing: 0.05em;
  font-weight: 900;
}

.articles ul {
  list-style: none;
  padding-left: 0;
  max-width: 720px;
  margin-left: auto;
  margin-right: auto;
}

.articles li {
  background: #fafafa;
  margin-bottom: 1.5rem;
  padding: 1.3rem 2rem;
  border-radius: var(--radius);
  box-shadow: 0 10px 25px rgba(74, 144, 226, 0.15);
  font-weight: 700;
  font-size: 1.2rem;
  color: var(--color-primary-dark);
  transition:
    transform 0.4s cubic-bezier(0.4, 0, 0.2, 1),
    box-shadow 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
}

.articles li:hover {
  transform: translateY(-5px) scale(1.02);
  box-shadow: 0 25px 45px rgba(245, 166, 35, 0.3);
}

.articles li a {
  color: inherit;
  text-decoration: none;
}

.articles li:hover a {
  text-decoration: underline;
  color: var(--color-accent);
}

/* Article content styles */
article {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 1rem;
  line-height: 1.7;
  color: var(--color-text);
  font-weight: 400;
  font-size: 1.1rem;
}

article em {
  font-style: italic;
  color: var(--color-text-light);
  font-size: 0.95rem;
}

article p {
  margin-bottom: 1.25rem;
}

article ul, article ol {
  margin-left: 1.8rem;
  margin-bottom: 1.5rem;
}

article ul li, article ol li {
  margin-bottom: 0.7rem;
  font-weight: 500;
}

article table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 2rem;
}

article th,
article td {
  border: 1px solid #ddd;
  padding: 0.7rem 1.2rem;
  text-align: left;
  font-weight: 600;
  background-color: #f7f9fc;
}

article code {
  background-color: #f0f4f8;
  padding: 0.25rem 0.5rem;
  border-radius: 5px;
  font-family: 'Courier New', Courier, monospace;
  font-size: 1rem;
}

/* Footer */
footer {
  text-align: center;
  padding: 3rem 1rem;
  font-size: 0.95rem;
  color: var(--color-text-light);
  letter-spacing: 0.1em;
  border-top: 2px solid #eee;
  margin-top: 5rem;
  user-select: none;
}
#backToTop {
  position: fixed;
  bottom: 30px;
  right: 30px;
  display: none;
  background: var(--color-primary);
  color: white;
  border: none;
  border-radius: 50%;
  width: 48px;
  height: 48px;
  font-size: 28px;
  line-height: 48px;
  text-align: center;
  cursor: pointer;
  box-shadow:
    0 4px 8px rgba(74, 144, 226, 0.3),
    0 8px 20px rgba(74, 144, 226, 0.2);
  transition: 
    background-color 0.3s ease,
    transform 0.3s ease,
    box-shadow 0.3s ease;
  z-index: 10000;
  user-select: none;
}

#backToTop:hover {
  background: var(--color-primary-dark);
  transform: scale(1.1);
  box-shadow:
    0 6px 12px rgba(74, 144, 226, 0.4),
    0 12px 30px rgba(74, 144, 226, 0.3);
}

#backToTop:focus {
  outline: none;
  box-shadow:
    0 0 0 3px rgba(74, 144, 226, 0.6);
}

/* Responsive */
@media (max-width: 768px) {
  body {
    padding: 0 var(--spacing);
  }
  header h1 {
    font-size: 2.5rem;
  }
  main {
    padding: 2rem 1.5rem;
  }
  .hero h2 {
    font-size: 2.5rem;
  }
  .hero p {
    font-size: 1.15rem;
  }
  .articles h3 {
    font-size: 1.8rem;
  }
  .articles li {
    font-size: 1.05rem;
    padding: 1rem 1.3rem;
  }
  nav ul {
    gap: 1rem;
  }
  nav ul li a {
    font-size: 1rem;
  }
}

@media (max-width: 480px) {
  nav ul {
    flex-wrap: wrap;
    gap: 0.7rem;
  }
  nav ul li a {
    font-size: 0.9rem;
    padding: 0.2rem 0;
  }
  header h1 {
    font-size: 2rem;
  }
}