:root {
  --background: #F7FAFC;            /* Light background */
  --foreground: hsl(220, 20%, 15%); /* Dark text for readability */
  --card: #FFFFFF;                  /* Card background */
  --card-foreground: hsl(220, 20%, 15%);
  --primary: #00C982;               /* Keep the same vibrant green */
  --primary-foreground: #FFFFFF;    /* Text on primary buttons */
  --secondary: #EDF2F7;             /* Light secondary sections */
  --secondary-foreground: hsl(220, 20%, 15%);
  --muted: #E6ECEF;                 /* Subtle muted background */
  --muted-foreground: hsl(220, 10%, 55%); /* Subtle text */
  --border: #D1D9E0;                /* Borders for pills, inputs */
  --radius: 0.5rem;
  --gradient-card: linear-gradient(180deg, transparent 0%, hsla(168, 76%, 42%, 0.15) 100%);
  --gradient-featured: linear-gradient(135deg, hsla(168, 76%, 42%, 0.1) 0%, hsla(168, 76%, 42%, 0.2) 100%);
  --glow-primary: 0 0 40px hsla(168, 76%, 42%, 0.1);
  --accent-1: #00C982;
  --accent-2: #00E4FF;
  --cta-gradient: linear-gradient(135deg, var(--accent-1), var(--accent-2));
}


body {
  background-color: var(--background);
  color: var(--foreground);
  font-family: 'Inter', sans-serif;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  scroll-behavior: smooth;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
}

/* Hero Section */
.hero {
  padding: 2rem 0 3rem;
  text-align: center;
}

.hero h1 {
  font-size: 3rem;
  font-weight: 800;
  margin-bottom: 1.5rem;
  letter-spacing: -0.02em;
  color: var(--foreground);
}

.hero p {
  color: var(--muted-foreground);
  font-size: 1.125rem;
  max-width: 700px;
  margin: 0 auto 2rem;
}

.btn-primary {
  display: inline-block;
  background: var(--cta-gradient);
  color: var(--primary-foreground);
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius);
  font-weight: 600;
  text-decoration: none;
  transition: all 0.3s ease;
  box-shadow: var(--glow-primary);
  border: none;
  cursor: pointer;
}

.btn-primary:hover {
  filter: brightness(1.1);
  box-shadow: 0 0 60px hsla(168, 76%, 42%, 0.2);
}


/* Section Headers */
.section-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
}

.section-header h2 {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--foreground);
}

.section-link {
  color: var(--primary);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.3s;
}

.section-link:hover {
  text-decoration: underline;
}


/* Articles Grid */
.articles-section {
  padding: 3rem 0;
}

.articles-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
}

.article-card {
  border-radius: var(--radius);
  overflow: hidden;
  position: relative;
  transition: transform 0.3s ease;
  background: var(--card); /* light mode card background */
  cursor: pointer;
  box-shadow: 0 3px 6px rgba(0,0,0,0.08);
}

.article-card:hover {
  transform: scale(1.02);
  box-shadow: 0 6px 12px rgba(0,0,0,0.12);
}

.article-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: var(--radius);
  background: linear-gradient(180deg, transparent 40%, hsla(0, 0%, 0%, 0.05) 100%);
  z-index: 1;
  pointer-events: none;
}

.article-card img {
  width: 100%;
  height: 200px;
  object-fit: cover;
}

.article-card-content {
  padding: 1rem;
  position: relative;
  z-index: 2;
}

.tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.25rem 0.75rem;
  border-radius: 4px;
  background-color: var(--primary);
  color: var(--primary-foreground);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.5rem;
}

.article-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  line-height: 1.4;
  color: var(--foreground);
}

.article-meta {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--muted-foreground);
  font-size: 0.875rem;
}


/* Categories Section */
.categories-section {
  padding: 3rem 0;
}

.categories-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.category-pill {
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius);
  font-weight: 500;
  background-color: var(--secondary); /* light mode: light card background */
  color: var(--foreground);
  border: 1px solid var(--border);
  cursor: pointer;
  transition: all 0.3s ease;
  text-decoration: none;
}

.category-pill:hover {
  border-color: var(--primary);
  background-color: var(--muted); /* subtle hover contrast */
}


/* Latest Posts Section */
.latest-section {
  padding: 3rem 0;
}

.latest-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
}

.featured-card {
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--gradient-featured); /* subtle light gradient */
  cursor: pointer;
}

.featured-card img {
  width: 100%;
  height: 300px;
  object-fit: cover;
}

.featured-card-content {
  padding: 1.5rem;
}

.featured-card h3 {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
}

.featured-card p {
  color: var(--muted-foreground); /* lighter text for descriptions */
  margin-bottom: 1rem;
  font-size: 0.875rem;
}

/* Sidebar Posts */
.sidebar-posts {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.sidebar-post {
  display: flex;
  gap: 1rem;
  padding: 1rem;
  background-color: var(--card); /* light card background */
  border-radius: var(--radius);
  transition: background-color 0.3s;
  cursor: pointer;
}

.sidebar-post:hover {
  background-color: var(--secondary); /* slightly darker card hover */
}

.sidebar-post img {
  width: 80px;
  height: 80px;
  object-fit: cover;
  border-radius: var(--radius);
  flex-shrink: 0;
}

.sidebar-post-content h4 {
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  line-height: 1.4;
}

.sidebar-post-content p {
  color: var(--muted-foreground); /* soft text for light mode */
  font-size: 0.75rem;
}


/* Suggest Topic Section */
.suggest-section, .newsletter-section {
  padding: 3rem 0 5rem;
}

.suggest-card {
  background-color: var(--card); /* light card background */
  border-radius: var(--radius);
  padding: 3rem;
  text-align: center;
  box-shadow: 0 4px 10px rgba(0,0,0,0.05); /* subtle light shadow for depth */
}

.suggest-card h2 {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--foreground);
}

.suggest-card p {
  color: var(--muted-foreground); /* soft text */
  margin-bottom: 1.5rem;
}

.suggest-form {
  display: flex;
  gap: 1rem;
  max-width: 700px;
  margin: 0 auto;
}

.suggest-form input {
  flex: 1;
  padding: 0.75rem 1rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background-color: var(--secondary); /* light input background */
  color: var(--foreground);
  font-size: 1rem;
  outline: none;
  transition: border-color 0.3s;
}

.suggest-form input:focus {
  border-color: var(--primary);
}

.suggest-form input::placeholder {
  color: var(--muted-foreground);
}

.suggest-form button {
  background: var(--cta-gradient);
  color: var(--primary-foreground);
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius);
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: all 0.3s ease;
  box-shadow: var(--glow-primary);
}

.suggest-form button:hover {
  filter: brightness(1.1);
  box-shadow: 0 0 60px hsla(168, 76%, 42%, 0.3);
}

/* Responsive Design */
@media (max-width: 1024px) {
  .articles-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .latest-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .hero h1 {
    font-size: 2rem;
  }
  
  .hero p {
    font-size: 1rem;
  }
  
  .articles-grid {
    grid-template-columns: 1fr;
  }
  
  .section-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }
  
  .suggest-form {
    flex-direction: column;
  }
  
  .suggest-card {
    padding: 2rem 1rem;
  }
}

@media (max-width: 480px) {
  .hero {
    padding: 2rem 0 2rem;
  }
  
  .hero h1 {
    font-size: 1.75rem;
  }
  
  .categories-grid {
    justify-content: center;
  }
  
  .sidebar-post {
    flex-direction: column;
  }
  
  .sidebar-post img {
    width: 100%;
    height: 150px;
  }
}

.popup {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%) scale(0);
  background-color: #ffffff; /* light background */
  padding: 35px 25px;
  border-radius: 12px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.1); /* lighter shadow */
  text-align: center;
  transition: transform 0.3s ease-in-out, opacity 0.3s ease-in-out;
  opacity: 0;
  z-index: 1000;
  border: 1px solid #e0e0e0; /* subtle border for light theme */
}

.popup.show {
  transform: translate(-50%, -50%) scale(1);
  opacity: 1;
}

.popup h2 {
  color: hsl(168, 76%, 42%); /* primary brand color */
  margin-bottom: 15px;
  font-size: 26px;
}

.popup p {
  color: #555555; /* dark gray for text readability */
  margin-bottom: 25px;
  font-size: 15px;
}

.popup .notify-btn {
  background-color: hsl(168, 76%, 42%); /* primary color button */
  color: #ffffff;
  padding: 12px 25px;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  font-size: 16px;
  transition: background-color 0.2s ease-in-out;
}

.popup .notify-btn:hover {
  background-color: hsl(168, 76%, 35%);
}

.popup-close {
  position: absolute;
  top: 10px;
  right: 15px;
  font-size: 22px;
  cursor: pointer;
  color: #333333; /* darker for light theme */
}


.popup {
  transform: translate(-50%, -50%) scale(0);
  opacity: 0;
  transition: transform 0.3s ease-in-out, opacity 0.3s ease-in-out;
}

.popup.show {
  transform: translate(-50%, -50%) scale(1);
  opacity: 1;
}