/* Base Variables (Light Theme) */
:root {
  --bg: #f5f5f5;
  --text: #222;
  --accent: #2196f3;
  --card-bg: #fff;
  --button-bg: #333;
  --button-text: #fff;
  --shadow: rgba(0, 0, 0, 0.06);
}

/* Dark Theme Overrides */
html[data-theme='dark'] {
  --bg: #1e1e1e;
  --text: #ddd;
  --accent: #64b5f6;
  --card-bg: #2b2b2b;
  --button-bg: #eee;
  --button-text: #111;
  --shadow: rgba(255, 255, 255, 0.05);
}

/* Reset & Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  background-color: var(--bg);
  color: var(--text);
  font-family: 'Georgia', serif;
  line-height: 1.7;
  transition: background-color 0.4s ease, color 0.4s ease;
  padding: 20px;
}

/* Header */
.page-header {
  margin-bottom: 2rem;
}
.header-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 10px;
}
.back-button {
  background: var(--button-bg);
  color: var(--button-text);
  padding: 8px 16px;
  text-decoration: none;
  border-radius: 5px;
  transition: background 0.3s ease, transform 0.3s;
}
.back-button:hover {
  background: var(--accent);
  transform: translateY(-2px);
}
.theme-toggle {
  font-size: 1.2rem;
  background: var(--button-bg);
  color: var(--button-text);
  border: none;
  border-radius: 5px;
  padding: 8px 12px;
  cursor: pointer;
  transition: background 0.3s ease;
}
.theme-toggle:hover {
  background: var(--accent);
}
.challenge-title {
  font-size: 1.5rem;
  margin-bottom: 10px;
}
.challenge-desc {
  background: rgba(33, 150, 243, 0.1);
  padding: 12px 16px;
  border-left: 4px solid var(--accent);
  font-size: 0.95rem;
  border-radius: 5px;
}

/* Layout */
.container {
  display: flex;
  gap: 20px;
  align-items: flex-start;
}

/* Sidebar */
.sidebar {
  flex: 1;
  background: var(--card-bg);
  padding: 15px;
  border: 1px solid #ccc;
  border-radius: 8px;
  position: sticky;
  top: 20px;
  height: fit-content;
  box-shadow: 0 4px 8px var(--shadow);
  transition: background 0.4s ease, color 0.4s ease;
}

/* Article */
.news {
  flex: 3;
  column-count: 4;
  column-gap: 40px;
  background: var(--card-bg);
  padding: 20px;
  border-radius: 8px;
  box-shadow: 0 4px 10px var(--shadow);
  transition: background 0.4s ease, color 0.4s ease;
}
.news h2 {
  column-span: all;
  font-size: 1.6rem;
  margin-bottom: 10px;
}
.news img {
  width: 100%;
  height: auto;
  object-fit: cover;
  margin-bottom: 1rem;
  border-radius: 6px;
  transition: transform 0.3s ease;
}
.news img:hover {
  transform: scale(1.01);
}

/* Responsive Design */
@media (max-width: 900px) {
  .news {
    column-count: 1;
  }
}
@media (max-width: 768px) {
  .container {
    flex-direction: column;
  }
  .sidebar {
    position: static;
    width: 100%;
    margin-bottom: 20px;
  }
}