:root {
  --bg: #0d1117;
  --card-bg: #161b22;
  --card-border: #30363d;
  --text: #e6edf3;
  --text-muted: #8b949e;
  --accent: #58a6ff;
  --accent-hover: #79c0ff;
  --shadow: rgba(0, 0, 0, 0.3);
}

[data-theme='light'] {
  --bg: #f6f8fa;
  --card-bg: #ffffff;
  --card-border: #d0d7de;
  --text: #24292f;
  --text-muted: #57606a;
  --accent: #0969da;
  --accent-hover: #0550ae;
  --shadow: rgba(0, 0, 0, 0.12);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  background: radial-gradient(circle at top, rgba(88, 166, 255, 0.12), transparent 45%), var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  transition:
    background 0.3s ease,
    color 0.3s ease;
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 2rem 1.5rem;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
}

h1 {
  font-size: 1.75rem;
  font-weight: 600;
}

.header-controls {
  display: flex;
  gap: 0.5rem;
}

.theme-toggle,
.lang-toggle {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 8px;
  padding: 0.5rem 0.75rem;
  cursor: pointer;
  color: var(--text);
  transition:
    border-color 0.2s ease,
    box-shadow 0.2s ease;
}

.theme-toggle {
  font-size: 1.25rem;
}

.lang-toggle {
  font-size: 0.875rem;
  font-weight: 600;
}

.theme-toggle:hover,
.lang-toggle:hover {
  border-color: var(--accent);
}

button:focus-visible,
a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.3);
}

.intro {
  color: var(--text-muted);
  margin-bottom: 2.5rem;
  font-size: 1.1rem;
}

.section-title {
  font-size: 0.875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--card-border);
}

.grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  margin-bottom: 2.5rem;
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 12px;
  padding: 1.25rem;
  text-decoration: none;
  color: var(--text);
  transition:
    border-color 0.2s ease,
    box-shadow 0.2s ease,
    transform 0.2s ease;
  display: flex;
  flex-direction: column;
}

.card:hover {
  border-color: var(--accent);
  box-shadow: 0 4px 12px var(--shadow);
  transform: translateY(-2px);
}

.card-selected {
  border-color: var(--accent);
  box-shadow: 0 4px 12px var(--shadow);
  transform: translateY(-2px);
}

.card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
}

.card-title-row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  min-width: 0;
}

.card-icon {
  font-size: 1.5rem;
  line-height: 1;
}

.card-title {
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.2;
}

.card-desc {
  font-size: 0.875rem;
  color: var(--text-muted);
  flex-grow: 1;
}

.card-link {
  color: var(--accent);
  font-size: 1.25rem;
  font-weight: 700;
  line-height: 1;
  flex-shrink: 0;
  transition:
    color 0.2s ease,
    transform 0.2s ease;
}

.card:hover .card-link,
.card-selected .card-link {
  color: var(--accent-hover);
  transform: translateX(1px);
}

.activity-section {
  margin-bottom: 2.5rem;
}

.activity-list {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 12px;
  overflow: hidden;
}

.activity-item {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  padding: 0.875rem 1rem;
  border-bottom: 1px solid var(--card-border);
  font-size: 0.875rem;
}

.activity-item:last-child {
  border-bottom: none;
}

.activity-icon {
  flex-shrink: 0;
  width: 1.5rem;
  text-align: center;
}

.activity-content {
  flex-grow: 1;
  min-width: 0;
}

.activity-text {
  color: var(--text);
  word-break: break-word;
}

.activity-text a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

.activity-text a:hover {
  text-decoration: underline;
}

.activity-time {
  color: var(--text-muted);
  font-size: 0.75rem;
  margin-top: 0.25rem;
}

.activity-loading,
.activity-error {
  padding: 2rem;
  text-align: center;
  color: var(--text-muted);
}

.activity-error a {
  color: var(--accent);
  text-decoration: none;
}

footer {
  text-align: center;
  padding-top: 1rem;
  border-top: 1px solid var(--card-border);
}

footer a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

footer a:hover {
  text-decoration: underline;
}

@media (max-width: 600px) {
  .grid {
    grid-template-columns: 1fr;
  }

  h1 {
    font-size: 1.5rem;
  }

  .activity-item {
    padding: 0.75rem;
  }

  .activity-text {
    font-size: 0.8125rem;
  }
}