:root {
  --bg-color: #121212;
  --header-bg: rgba(18, 18, 18, 0.8);
  --text-color: #e0e0e0;
  --secondary-text: #b0b0b0;
  --card-bg: #1e1e1e;
  --accent-color: #bb86fc;
  --border-color: #333;
  --modal-overlay: rgba(0, 0, 0, 0.7);
  --header-shadow: 0 4px 12px rgba(0, 0, 0, 0.5);
}

body.light-mode {
  --bg-color: #f8f9fa;
  --header-bg: rgba(255, 255, 255, 0.8);
  --text-color: #212529;
  --secondary-text: #6c757d;
  --card-bg: #ffffff;
  --accent-color: #3f51b5;
  --border-color: #e0e0e0;
  --modal-overlay: rgba(0, 0, 0, 0.5);
  --header-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: 'Apple SD Gothic Neo', 'Malgun Gothic', sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
  transition: background-color 0.3s ease, color 0.3s ease;
}

.header {
  position: sticky;
  top: 0;
  background-color: var(--header-bg);
  backdrop-filter: blur(8px);
  z-index: 100;
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--header-shadow);
}

.header-content {
  max-width: 900px;
  margin: 0 auto;
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.5rem;
  font-weight: 800;
  letter-spacing: -1px;
}

.header-actions {
  display: flex;
  gap: 1.5rem;
}

.action-btn, .theme-toggle {
  background: none;
  border: none;
  color: var(--text-color);
  font-size: 1.2rem;
  cursor: pointer;
  transition: opacity 0.2s;
}

.action-btn:hover, .theme-toggle:hover {
  opacity: 0.7;
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 3rem 2rem;
}

.intro {
  margin-bottom: 4rem;
  text-align: center;
}

.intro-text {
  font-size: 1.2rem;
  color: var(--secondary-text);
  font-weight: 300;
}

.posts-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
  gap: 2.5rem;
}

.post-card {
  background-color: var(--card-bg);
  border-radius: 12px;
  padding: 2rem;
  border: 1px solid var(--border-color);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  cursor: pointer;
}

.post-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.post-tag {
  display: inline-block;
  font-size: 0.8rem;
  color: var(--accent-color);
  font-weight: 600;
  margin-bottom: 0.5rem;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.post-title {
  font-size: 1.6rem;
  font-weight: 700;
  margin-bottom: 1rem;
  word-break: keep-all;
}

.post-content-preview {
  font-size: 1rem;
  color: var(--secondary-text);
  margin-bottom: 1.5rem;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.post-date {
  font-size: 0.85rem;
  color: var(--secondary-text);
  border-top: 1px solid var(--border-color);
  padding-top: 1rem;
  display: block;
}

/* Modal */
.modal {
  display: none;
  position: fixed;
  z-index: 200;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background-color: var(--modal-overlay);
  backdrop-filter: blur(4px);
}

.modal-content {
  background-color: var(--card-bg);
  margin: 5% auto;
  padding: 3rem;
  width: 90%;
  max-width: 600px;
  border-radius: 16px;
  position: relative;
}

.close-btn {
  position: absolute;
  top: 20px;
  right: 25px;
  font-size: 2rem;
  cursor: pointer;
  color: var(--secondary-text);
}

h2 {
  margin-bottom: 2rem;
  font-size: 1.8rem;
}

.form-group {
  margin-bottom: 1.5rem;
}

label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 600;
}

input, textarea {
  width: 100%;
  padding: 1rem;
  background-color: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  color: var(--text-color);
  font-family: inherit;
  font-size: 1rem;
}

input:focus, textarea:focus {
  outline: none;
  border-color: var(--accent-color);
}

.submit-btn {
  width: 100%;
  padding: 1.2rem;
  background-color: var(--accent-color);
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 1.1rem;
  font-weight: 700;
  cursor: pointer;
  transition: opacity 0.2s;
  margin-top: 1rem;
}

.submit-btn:hover {
  opacity: 0.9;
}

@media (max-width: 600px) {
  .posts-grid {
    grid-template-columns: 1fr;
  }
  .modal-content {
    margin: 10% auto;
    padding: 2rem;
  }
}