/* =========================================
   CSS Custom Properties
   ========================================= */
:root {
  --color-primary: #1a1a2e;
  --color-secondary: #16213e;
  --color-accent: #0f3460;
  --color-highlight: #e94560;
  --color-text: #333333;
  --color-text-light: #666666;
  --color-bg: #ffffff;
  --color-bg-sub: #f8f8f8;
  --color-border: #e0e0e0;

  --font-base: 'futura-pt', 'Noto Sans JP', sans-serif;
  --font-heading: 'Noto Sans JP', sans-serif;

  --fs-xs: 0.75rem;
  --fs-sm: 0.875rem;
  --fs-s: 0.9375rem;
  --fs-base: 1rem;
  --fs-md: 1.125rem;
  --fs-lg: 1.25rem;
  --fs-xl: 1.5rem;
  --fs-2xl: 2rem;
  --fs-3xl: 2.5rem;

  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 2rem;
  --spacing-xl: 2.5rem;
  --spacing-xxl: 4rem;

  --max-width: 1200px;
  --radius: 4px;
  --transition: 0.3s ease;
}

/* =========================================
   Reset & Base
   ========================================= */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-base);
  font-size: var(--fs-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.8;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}
a {
  color: var(--color-accent);
  text-decoration: none;
  transition: opacity var(--transition);
}
a:hover {
  opacity: 0.7;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: var(--font-heading);
  line-height: 1.4;
  font-weight: 700;
}

/* =========================================
   Layout
   ========================================= */
.content-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.section {
  padding: var(--spacing-xl) 0;
}

/* =========================================
   Page Header
   ========================================= */
.page-header {
  margin-bottom: var(--spacing-xl);
  text-align: center;
}

.page-subtitle {
  display: block;
  font-size: var(--fs-sm);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-highlight);
  margin-bottom: var(--spacing-sm);
}

.page-title {
  font-size: var(--fs-3xl);
  margin-bottom: var(--spacing-md);
}

.page-intro {
  color: var(--color-text-light);
  max-width: 600px;
  margin: 0 auto;
}

/* =========================================
   Post Cards
   ========================================= */
.posts-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-xl);
}

.post-card {
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: box-shadow var(--transition);
}

.post-card:hover {
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

.post-card-body {
  padding: var(--spacing-lg);
}

.entry-title {
  font-size: var(--fs-lg);
  margin-bottom: var(--spacing-sm);
}
.entry-meta {
  font-size: var(--fs-xs);
  color: var(--color-text-light);
  margin-bottom: var(--spacing-md);
}

/* =========================================
   Buttons
   ========================================= */
.btn {
  display: inline-block;
  padding: 0.75em 2em;
  border-radius: var(--radius);
  font-weight: 600;
  transition: var(--transition);
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--color-highlight);
  color: #fff;
}

.btn-primary:hover {
  background: var(--color-accent);
  opacity: 1;
  color: #fff;
}

/* =========================================
   404
   ========================================= */
.error-404 {
  text-align: center;
  padding: var(--spacing-xl) 0;
}
.error-404 .page-title {
  font-size: var(--fs-3xl);
  margin-bottom: var(--spacing-lg);
}

/* =========================================
   Responsive
   ========================================= */
@media (max-width: 768px) {
  :root {
    --fs-3xl: 1.75rem;
    --fs-2xl: 1.5rem;
  }

  .content-container {
    padding: 0 var(--spacing-md);
  }

  .menu-toggle {
    display: flex;
  }

  .main-navigation ul {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    padding: var(--spacing-md) var(--spacing-lg);
    gap: var(--spacing-md);
  }

  .main-navigation.is-open ul {
    display: flex;
  }

  .posts-list {
    grid-template-columns: 1fr;
  }
}