:root {
  --color-primary: #1a1a1a;
  --color-text: #2c3e50;
  --color-light: #666;
  --color-border: #e0e0e0;
  --color-bg: #f8f9fa;
  --color-white: #ffffff;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, sans-serif;
  --border-radius: 8px;
  --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
  --transition: all 0.3s ease;
}

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

body {
  font-family: var(--font-sans);
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
  min-height: 100vh;
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 60px 30px;
}

/* Navigation */
.nav {
  background: var(--color-white);
  border-bottom: 1px solid var(--color-border);
  padding: 20px 0;
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav__container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 900px;
  margin: 0 auto;
  padding: 0 30px;
}

.nav__logo {
  font-size: 24px;
  font-weight: 600;
  color: var(--color-primary);
  text-decoration: none;
  letter-spacing: -0.5px;
}

.nav__options {
  display: flex;
  align-items: center;
  gap: 15px;
}

/* User Section in Nav */
.user-section-nav {
  display: flex;
  align-items: center;
  gap: 10px;
}

.user-info {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 20px;
}

.user-avatar {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--color-primary);
  color: var(--color-white);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 14px;
}

.user-info span {
  font-size: 14px;
  color: var(--color-primary);
}

/* Buttons */
.btn {
  padding: 12px 24px;
  border: none;
  border-radius: var(--border-radius);
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  transition: var(--transition);
  font-family: var(--font-sans);
}

.btn-primary {
  background: var(--color-primary);
  color: var(--color-white);
}

.btn-primary:hover {
  background: #333;
  transform: translateY(-1px);
}

.btn-secondary {
  background: var(--color-bg);
  color: var(--color-primary);
  border: 1px solid var(--color-border);
  padding: 8px 16px;
  font-size: 13px;
}

.btn-secondary:hover {
  background: var(--color-primary);
  color: var(--color-white);
}

/* Heading Section */
.heading {
  padding: 60px 0;
  background: var(--color-bg);
  text-align: center;
}

.heading__body {
  max-width: 800px;
  margin: 0 auto;
}

.heading__headline h1 {
  font-size: 42px;
  margin-bottom: 30px;
  line-height: 1.3;
  color: var(--color-primary);
  letter-spacing: -0.5px;
}

.heading__content {
  font-size: 18px;
  color: var(--color-light);
  line-height: 1.8;
}

/* Search Section */
.search-section {
  padding: 40px 0;
}

.tabs {
  display: flex;
  gap: 8px;
  margin-bottom: 32px;
  justify-content: center;
  border-bottom: 1px solid var(--color-border);
  padding-bottom: 8px;
}

.tab {
  background: none;
  border: none;
  padding: 12px 24px;
  font-size: 16px;
  font-weight: 500;
  color: var(--color-light);
  cursor: pointer;
  position: relative;
  transition: color 0.3s ease;
  border-bottom: 2px solid transparent;
}

.tab:hover {
  color: var(--color-primary);
}

.tab.active {
  color: var(--color-primary);
  border-bottom: 2px solid var(--color-primary);
}

.search-pane {
  max-width: 800px;
  margin: 0 auto;
}

.search-box {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.search-input {
  flex: 1;
  padding: 15px 20px;
  border: 1px solid var(--color-border);
  border-radius: 20px;
  font-size: 16px;
  font-family: var(--font-sans);
  transition: var(--transition);
  min-width: 300px;
}

.search-input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(26, 26, 26, 0.1);
}

/* Results Section */
.results-section {
  background: var(--color-white);
  padding: 40px 0;
}

.results {
  display: grid;
  gap: 24px;
  margin-top: 40px;
}

/* Cards */
.post-card {
  background: var(--color-white);
  padding: 28px;
  border-radius: var(--border-radius);
  transition: var(--transition);
  border: 1px solid var(--color-border);
  margin-bottom: 0;
}

.post-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
}

.post-date {
  font-size: 13px;
  color: var(--color-light);
  margin-bottom: 12px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.post-card h3 {
  font-size: 20px;
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: 12px;
  line-height: 1.3;
  transition: color 0.3s ease;
}

.post-card h3:hover {
  color: #333;
}

.post-card p {
  font-size: 15px;
  color: var(--color-light);
  line-height: 1.6;
  margin-bottom: 16px;
}

.badge {
  display: inline-block;
  padding: 6px 12px;
  background: #e0e7ff;
  color: #1a1a1a;
  border-radius: 12px;
  font-size: 12px;
  font-weight: 500;
  margin-right: 8px;
  margin-bottom: 8px;
}

.similarity-badge {
  display: inline-block;
  padding: 6px 12px;
  background: #d1fae5;
  color: #059669;
  border-radius: 12px;
  font-size: 13px;
  font-weight: 500;
  margin-bottom: 15px;
}

.date-badge {
  padding: 4px 10px;
  background: var(--color-bg);
  color: var(--color-light);
  border-radius: 12px;
  font-size: 12px;
  margin-right: 8px;
}

.card__actions {
  display: flex;
  gap: 10px;
  margin-top: 15px;
  flex-wrap: wrap;
}

.common-button {
  display: inline-block;
  background: var(--color-primary);
  color: var(--color-white);
  padding: 10px 20px;
  border-radius: 6px;
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
  border: none;
  cursor: pointer;
  font-family: var(--font-sans);
  font-size: 14px;
}

.common-button:hover {
  background: #333;
  transform: translateX(4px);
}

.common-button--secondary {
  background: var(--color-bg);
  color: var(--color-primary);
  border: 1px solid var(--color-border);
}

.common-button--secondary:hover {
  background: var(--color-primary);
  color: var(--color-white);
}

/* Empty State */
.empty-state {
  text-align: center;
  padding: 60px 20px;
  background: var(--color-white);
  border-radius: var(--border-radius);
  border: 1px solid var(--color-border);
}

.empty-state h3 {
  font-size: 24px;
  margin-bottom: 10px;
  color: var(--color-primary);
}

.empty-state p {
  color: var(--color-light);
  font-size: 16px;
}

/* Loading */
.loading {
  text-align: center;
  padding: 60px 20px;
}

.spinner {
  border: 3px solid var(--color-border);
  border-top: 3px solid var(--color-primary);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  animation: spin 1s linear infinite;
  margin: 0 auto 15px;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

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

/* Footer */
.footer {
  margin-top: 80px;
  padding-top: 30px;
  border-top: 1px solid var(--color-border);
  text-align: center;
}

.footer__content p {
  color: var(--color-light);
  font-size: 14px;
}

/* Tab Content Animation */
.tab-content {
  display: none;
  animation: fadeIn 0.4s ease;
}

.tab-content.active {
  display: block;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Hidden utility */
.hidden {
  display: none !important;
}

/* Responsive */
@media (max-width: 768px) {
  .container {
    padding: 40px 20px;
  }

  .heading__headline h1 {
    font-size: 32px;
  }

  .nav__container {
    flex-direction: column;
    gap: 15px;
  }

  .nav__options {
    width: 100%;
    justify-content: center;
  }

  .tabs {
    flex-direction: column;
    align-items: stretch;
    gap: 4px;
  }

  .tab {
    width: 100%;
    text-align: center;
  }

  .search-box {
    flex-direction: column;
  }

  .search-input {
    width: 100%;
    min-width: auto;
  }

  .post-card {
    padding: 20px;
  }

  .post-card h3 {
    font-size: 18px;
  }
}