/* CSS Variables */
:root {
  --color-background: #e7eff5;
  --color-text: #1f2937; /* Darker for better contrast (was #393f4d) */
  --color-text-secondary: #4b5563; /* Darker for WCAG AA compliance (was #666666) */
  --color-border: #9ca3af; /* Darker border for better visibility (was #d1dae3) */
  --color-card-bg: #ffffff;
  --color-card-shadow: rgba(0, 0, 0, 0.1);
  --color-primary: #2563eb; /* Darker blue for better contrast (was #3b82f6) */
  --color-primary-hover: #1d4ed8; /* Adjusted hover state (was #2563eb) */
  --font-sans: "Noto Sans JP", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

[data-theme="dark"] {
  --color-background: #0f0f0f; /* Darker background for better contrast (was #1a1a1a) */
  --color-text: #ffffff;
  --color-text-secondary: #d1d5db; /* Lighter for WCAG AA compliance (was #a3a3a3) */
  --color-border: #4b5563; /* Lighter border for better visibility (was #333333) */
  --color-card-bg: #1f2937; /* Adjusted card background (was #262626) */
  --color-card-shadow: rgba(0, 0, 0, 0.5);
}

/* Reset and Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-family: var(--font-sans);
  line-height: 1.6;
  scroll-behavior: smooth;
}

body {
  background-color: var(--color-background);
  color: var(--color-text);
  transition: background-color 0.3s ease, color 0.3s ease;
}

/* Container */
.container {
  width: 100%;
  margin: 0 auto;
  padding: 0 1rem;
  max-width: 1200px;
}

@media (min-width: 640px) {
  .container {
    padding: 0 2rem;
  }
}

/* Header Styles */
header {
  border-bottom: 1px solid var(--color-border);
  background-color: var(--color-background);
  position: sticky;
  top: 0;
  z-index: 50;
  transition: background-color 0.3s ease;
}

.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 4rem;
}

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  text-decoration: none;
  color: var(--color-text);
  transition: color 0.2s ease;
}

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

nav {
  display: flex;
  align-items: center;
  gap: 1rem;
}

/* Theme Toggle */
.theme-toggle {
  padding: 0.5rem;
  border: 1px solid var(--color-border);
  background-color: transparent;
  color: var(--color-text);
  border-radius: 0.375rem;
  cursor: pointer;
  transition: all 0.2s ease;
  font-size: 1.25rem;
  line-height: 1;
}

.theme-toggle:hover {
  background-color: var(--color-border);
}

/* Hero Section */
.hero {
  padding: 5rem 0;
  text-align: center;
}

.hero h1 {
  font-size: 3rem;
  font-weight: 900;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, #2563eb, #06b6d4, #8b5cf6);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  background-size: 200% 200%;
  animation: gradient-shift 6s ease-in-out infinite;
}

@media (min-width: 768px) {
  .hero h1 {
    font-size: 4rem;
  }
}

.hero p {
  font-size: 1.25rem;
  color: var(--color-text-secondary);
  max-width: 42rem;
  margin: 0 auto;
}

/* Page Title */
.page-header {
  padding: 3rem 0;
  text-align: center;
}

.page-header h1 {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
}

.page-header p {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
}

/* Post Grid */
.post-grid {
  display: grid;
  gap: 2rem;
  padding: 2rem 0;
  grid-template-columns: 1fr;
}

@media (min-width: 768px) {
  .post-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .post-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* Post Card */
.post-card {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: 0.5rem;
  padding: 1.5rem;
  transition: all 0.3s ease;
  text-decoration: none;
  color: inherit;
  display: block;
}

.post-card:hover {
  box-shadow: 0 10px 30px var(--color-card-shadow);
  transform: translateY(-4px);
}

.post-card-emoji {
  font-size: 2.5rem;
  margin-bottom: 0.75rem;
  display: block;
}

.post-card h2 {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  line-height: 1.3;
}

.post-card-excerpt {
  color: var(--color-text-secondary);
  margin-bottom: 1rem;
  line-height: 1.5;
}

.post-card-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.post-card-date {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
}

.post-card-tags {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.tag {
  font-size: 0.75rem;
  padding: 0.25rem 0.5rem;
  background-color: var(--color-background);
  border: 1px solid var(--color-border);
  border-radius: 0.25rem;
  color: var(--color-text);
  font-weight: 500;
}

/* Article Styles */
article {
  max-width: 48rem;
  margin: 0 auto;
  padding: 3rem 0;
}

article h1 {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 1rem;
  line-height: 1.2;
}

@media (min-width: 768px) {
  article h1 {
    font-size: 3rem;
  }
}

.article-meta {
  display: flex;
  gap: 1rem;
  align-items: center;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--color-border);
  color: var(--color-text-secondary);
}

.article-content {
  font-size: 1.125rem;
  line-height: 1.8;
}

.article-content h2 {
  font-size: 2rem;
  font-weight: 700;
  margin: 2rem 0 1rem;
}

.article-content h3 {
  font-size: 1.5rem;
  font-weight: 600;
  margin: 1.5rem 0 0.75rem;
}

.article-content p {
  margin-bottom: 1.5rem;
}

.article-content ul,
.article-content ol {
  margin-bottom: 1.5rem;
  padding-left: 2rem;
}

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

.article-content code {
  background-color: var(--color-border);
  padding: 0.125rem 0.375rem;
  border-radius: 0.25rem;
  font-size: 0.875em;
}

.article-content pre {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: 0.5rem;
  padding: 1rem;
  overflow-x: auto;
  margin-bottom: 1.5rem;
}

.article-content pre code {
  background-color: transparent;
  padding: 0;
}

/* Footer */
footer {
  border-top: 1px solid var(--color-border);
  padding: 2rem 0;
  text-align: center;
  color: var(--color-text-secondary);
  font-size: 0.875rem;
}

/* Utility Classes */
.text-center {
  text-align: center;
}

.mt-4 {
  margin-top: 1rem;
}

.mb-4 {
  margin-bottom: 1rem;
}

.mt-8 {
  margin-top: 2rem;
}

.mb-8 {
  margin-bottom: 2rem;
}

/* Empty State */
.empty-state {
  text-align: center;
  padding: 4rem 0;
  color: var(--color-text-secondary);
}

/* Code Syntax Highlighting */
.code-block {
  position: relative;
  margin-bottom: 1.5rem;
  border-radius: 0.5rem;
  overflow: hidden;
}

.code-block pre[class*="language-"] {
  margin: 0 !important;
  border-radius: 0 !important;
  font-family: "Monaco", "Menlo", "Ubuntu Mono", monospace !important;
  font-size: 0.875rem !important;
  line-height: 1.5 !important;
}

.code-block code[class*="language-"] {
  font-family: "Monaco", "Menlo", "Ubuntu Mono", monospace !important;
}

/* Language Label */
.code-block::before {
  content: attr(data-language);
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  font-size: 0.75rem;
  color: #888;
  text-transform: uppercase;
  font-family: var(--font-sans);
  z-index: 10;
  background: rgba(0, 0, 0, 0.3);
  padding: 0.25rem 0.5rem;
  border-radius: 0.25rem;
}

/* Focus States */
button:focus,
a:focus {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* Transitions */
a,
button {
  transition: all 0.2s ease;
}

/* Gradient Animation */
@keyframes gradient-shift {
  0%,
  100% {
    background-position: 0% 50%;
  }
  50% {
    background-position: 100% 50%;
  }
}