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

:root {
  --color-bg: #ffffff;
  --color-text: #1f2328;
  --color-text-muted: #656d76;
  --color-link: #0969da;
  --color-link-hover: #0550ae;
  --color-border: #d0d7de;
  --color-bg-subtle: #f6f8fa;
  --color-bg-hover: #eef1f4;
  --color-accent: #0969da;
  --color-accent-subtle: #ddf4ff;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans", Helvetica, Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
  --max-width: 760px;
  --header-height: 60px;
  --radius: 8px;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
}

html {
  font-size: 16px;
  line-height: 1.7;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: var(--color-link);
  text-decoration: none;
  transition: color 0.15s;
}

a:hover {
  color: var(--color-link-hover);
}

/* ===== Container ===== */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
  width: 100%;
}

/* ===== Header ===== */
.site-header {
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  height: var(--header-height);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  display: flex;
  align-items: center;
  height: 100%;
  gap: 2rem;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text);
  text-decoration: none;
}

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

.logo-icon {
  width: 28px;
  height: 28px;
  object-fit: contain;
}

.logo-text {
  letter-spacing: -0.02em;
}

/* ===== Main Nav ===== */
.main-nav {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex: 1;
}

.nav-link {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  font-weight: 500;
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius);
  transition: background 0.15s, color 0.15s;
}

.nav-link:hover {
  color: var(--color-text);
  background: var(--color-bg-subtle);
  text-decoration: none;
}

/* Dropdown */
.nav-dropdown {
  position: relative;
}

.dropdown-menu {
  position: absolute;
  top: 100%;
  left: 0;
  min-width: 180px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity 0.2s, transform 0.2s, visibility 0.2s;
  padding: 0.5rem 0;
  margin-top: 0.25rem;
}

.nav-dropdown:hover .dropdown-menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.dropdown-menu a {
  display: block;
  padding: 0.5rem 1rem;
  color: var(--color-text-muted);
  font-size: 0.9rem;
  transition: background 0.15s, color 0.15s;
}

.dropdown-menu a:hover {
  background: var(--color-bg-subtle);
  color: var(--color-text);
  text-decoration: none;
}

/* ===== Language Switch ===== */
.lang-switch {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  font-size: 0.85rem;
  background: var(--color-bg-subtle);
  border-radius: var(--radius);
  padding: 0.25rem;
}

.lang-switch a,
.lang-switch .current {
  padding: 0.35rem 0.6rem;
  border-radius: 6px;
  font-weight: 500;
}

.lang-switch a {
  color: var(--color-text-muted);
  transition: background 0.15s, color 0.15s;
}

.lang-switch a:hover {
  background: var(--color-bg);
  color: var(--color-text);
  text-decoration: none;
}

.lang-switch .current {
  background: var(--color-bg);
  color: var(--color-accent);
  box-shadow: var(--shadow-sm);
}

/* ===== Main Content ===== */
.site-main {
  flex: 1;
  padding: 3rem 0;
}

.content h1 {
  font-size: 2.25rem;
  font-weight: 700;
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
  color: var(--color-text);
}

.content h1+p {
  font-size: 1.125rem;
  color: var(--color-text-muted);
  margin-bottom: 2rem;
}

.content h2 {
  font-size: 1.5rem;
  font-weight: 600;
  margin-top: 2.5rem;
  margin-bottom: 1rem;
  color: var(--color-text);
}

.content h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-top: 2rem;
  margin-bottom: 0.75rem;
}

.content p {
  margin-bottom: 1rem;
}

.content>p:first-of-type {
  font-size: 1.1rem;
  color: var(--color-text-muted);
}

/* ===== Card Navigation ===== */
.content ul {
  list-style: none;
  padding: 0;
  margin: 0 0 1.5rem 0;
}

.content>ul {
  display: grid;
  gap: 0.75rem;
}

.content>ul>li {
  margin: 0;
}

.content>ul>li>a {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem 1.25rem;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  color: var(--color-text);
  font-weight: 500;
  transition: border-color 0.15s, box-shadow 0.15s, transform 0.15s;
}

.content>ul>li>a:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-sm);
  transform: translateY(-1px);
  text-decoration: none;
}

.content>ul>li>a::before {
  content: "→";
  color: var(--color-accent);
  font-weight: 400;
}

/* Nested list (descriptions) */
.content>ul ul {
  margin-top: 0.5rem;
  padding-left: 1.5rem;
}

.content>ul ul li {
  list-style: disc;
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

/* ===== Blockquote ===== */
.content blockquote {
  margin: 1.5rem 0;
  padding: 1rem 1.25rem;
  background: var(--color-accent-subtle);
  border-left: 4px solid var(--color-accent);
  border-radius: 0 var(--radius) var(--radius) 0;
  color: var(--color-text);
}

.content blockquote p {
  margin-bottom: 0;
}

.content blockquote strong {
  color: var(--color-accent);
}

/* ===== Code ===== */
.content code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--color-bg-subtle);
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
  border: 1px solid var(--color-border);
}

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

.content pre code {
  background: none;
  padding: 0;
  border: none;
}

/* ===== HR ===== */
.content hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: 2.5rem 0;
}

/* ===== Ordered List (steps) ===== */
.content ol {
  padding-left: 1.5rem;
  margin-bottom: 1.5rem;
}

.content ol li {
  margin-bottom: 0.75rem;
  padding-left: 0.5rem;
}

/* ===== Back Link ===== */
.content>p:last-child>a[href^=".."],
.content>p:last-child>a[href^="./"],
.content>p:last-child>a[href="index.html"] {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--color-text-muted);
  font-size: 0.9rem;
  padding: 0.5rem 1rem;
  background: var(--color-bg-subtle);
  border-radius: var(--radius);
  transition: background 0.15s, color 0.15s;
}

.content>p:last-child>a[href^=".."]:hover,
.content>p:last-child>a[href^="./"]:hover {
  background: var(--color-bg-hover);
  color: var(--color-text);
  text-decoration: none;
}

/* ===== Footer ===== */
.site-footer {
  background: var(--color-bg-subtle);
  border-top: 1px solid var(--color-border);
  padding: 2rem 0;
  margin-top: auto;
}

.site-footer .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.site-footer p {
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

.footer-nav {
  display: flex;
  gap: 1.5rem;
}

.footer-nav a {
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

.footer-nav a:hover {
  color: var(--color-link);
}

/* ===== Responsive ===== */
@media (max-width: 640px) {
  :root {
    --header-height: 56px;
  }

  .header-inner {
    gap: 1rem;
  }

  .logo-text {
    display: none;
  }

  .main-nav {
    gap: 0.25rem;
  }

  .nav-link {
    padding: 0.5rem;
    font-size: 0.9rem;
  }

  .dropdown-menu {
    position: fixed;
    left: 1rem;
    right: 1rem;
    min-width: auto;
  }

  .site-main {
    padding: 2rem 0;
  }

  .content h1 {
    font-size: 1.75rem;
  }

  .content h2 {
    font-size: 1.25rem;
  }

  .site-footer .container {
    flex-direction: column;
    text-align: center;
  }

  .footer-nav {
    justify-content: center;
  }
}