:root {
  --bg-main: #ffffff;
  --bg-header-footer: #d32f2f; /* Deep Red */
  --primary: #d32f2f;
  --secondary: #b71c1c;
  --text-main: #212121;
  --text-light: #ffffff;
  --text-muted: #757575;
  --border-color: #e0e0e0;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Inter', system-ui, sans-serif;
}

body {
  background-color: var(--bg-main);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
}

/* Header */
header {
  padding: 1.5rem 5%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: var(--bg-header-footer);
  border-bottom: 2px solid var(--secondary);
  position: sticky;
  top: 0;
  z-index: 100;
}

.logo {
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--text-light);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.2rem;
}

.logo-highlight {
  background-color: #ffffff;
  color: var(--primary);
  padding: 0.1rem 0.4rem;
  border-radius: 0.3rem;
  font-weight: 900;
  margin-right: 0.2rem;
}

nav ul {
  display: flex;
  gap: 2rem;
  list-style: none;
}

nav a {
  color: var(--text-light);
  text-decoration: none;
  font-weight: 600;
  transition: opacity 0.3s;
}

nav a:hover {
  opacity: 0.8;
}

/* Tool Section */
.hero {
  padding: 5rem 5%;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  min-height: 60vh;
  justify-content: center;
  background: radial-gradient(circle at 50% -20%, #ffebee, var(--bg-main));
}

.hero h1 {
  font-size: 3.5rem;
  margin-bottom: 1rem;
  line-height: 1.2;
  color: var(--primary);
}

.hero p {
  color: var(--text-muted);
  margin-bottom: 3rem;
  font-size: 1.2rem;
  max-width: 600px;
}

.downloader-box {
  background: #ffffff;
  border: 1px solid var(--border-color);
  padding: 2.5rem;
  border-radius: 1.5rem;
  width: 100%;
  max-width: 800px;
  box-shadow: 0 10px 30px rgba(211, 47, 47, 0.1);
}

.input-group {
  display: flex;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.input-group input {
  flex: 1;
  padding: 1.2rem 1.5rem;
  border-radius: 0.75rem;
  border: 2px solid var(--border-color);
  background: #ffffff;
  color: var(--text-main);
  font-size: 1.1rem;
  outline: none;
  transition: border-color 0.3s;
}

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

.btn {
  padding: 1.2rem 2.5rem;
  border-radius: 0.75rem;
  border: none;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: white;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 20px -10px var(--primary);
}

.format-options {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin-top: 1rem;
}

.format-btn {
  background: #f5f5f5;
  border: 1px solid var(--border-color);
  padding: 0.8rem 2rem;
  border-radius: 0.5rem;
  color: var(--text-muted);
  cursor: pointer;
  transition: all 0.3s;
}

.format-btn.active {
  background: #ffebee;
  border-color: var(--primary);
  color: var(--primary);
  font-weight: 600;
}

/* Content Section (Article) */
.article-section {
  padding: 5rem 10%;
  max-width: 1200px;
  margin: 0 auto;
}

.article-section h2 {
  font-size: 2.5rem;
  margin: 3rem 0 1.5rem;
  color: var(--primary);
}

.article-section h3 {
  font-size: 1.8rem;
  margin: 2rem 0 1rem;
  color: var(--secondary);
}

.article-section p {
  margin-bottom: 1.5rem;
  color: var(--text-main);
  font-size: 1.1rem;
}

.article-section ul {
  margin-bottom: 1.5rem;
  padding-left: 2rem;
  color: var(--text-main);
}

.article-section li {
  margin-bottom: 0.5rem;
}

/* Footer */
footer {
  background: var(--bg-header-footer);
  padding: 4rem 5% 2rem;
  border-top: 2px solid var(--secondary);
  color: var(--text-light);
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
  max-width: 1200px;
  margin: 0 auto;
}

.footer-col h4 {
  margin-bottom: 1.5rem;
  color: var(--text-light);
}

.footer-col ul {
  list-style: none;
}

.footer-col li {
  margin-bottom: 0.8rem;
}

.footer-col a {
  color: rgba(255, 255, 255, 0.8);
  text-decoration: none;
  transition: color 0.3s;
}

.footer-col a:hover {
  color: #ffffff;
}

.footer-bottom {
  text-align: center;
  margin-top: 4rem;
  padding-top: 2rem;
  border-top: 1px solid rgba(255, 255, 255, 0.2);
  color: rgba(255, 255, 255, 0.7);
}

/* Responsive */
@media (max-width: 768px) {
  header {
    flex-direction: column;
    gap: 1rem;
    padding: 1rem;
  }
  
  nav ul {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 1rem;
    font-size: 0.9rem;
  }
  
  .hero {
    padding: 3rem 5%;
    min-height: auto;
  }
  
  .hero h1 { 
    font-size: 2.2rem; 
  }
  
  .hero p {
    font-size: 1rem;
    margin-bottom: 2rem;
  }
  
  .downloader-box {
    padding: 1.5rem;
  }
  
  .input-group { 
    flex-direction: column; 
    gap: 0.8rem;
  }
  
  .input-group input { 
    width: 100%; 
    padding: 1rem;
  }
  
  .btn { 
    width: 100%; 
    padding: 1rem;
  }
  
  .format-options {
    flex-direction: column;
    gap: 0.5rem;
  }
  
  .format-btn {
    width: 100%;
  }

  .article-section { 
    padding: 2rem 5%; 
  }
  
  .article-section h2 {
    font-size: 2rem;
  }
  
  .article-section h3 {
    font-size: 1.5rem;
  }
}

@media (max-width: 480px) {
  .hero h1 {
    font-size: 1.8rem;
  }
  .footer-content {
    grid-template-columns: 1fr;
    text-align: center;
  }
}