/* ==============================================================================
   SELFSO.COM - Modern Minimalist Light (Zen / Editorial Paper) Design System
   ============================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=JetBrains+Mono:wght@400;500;600&family=Lora:ital,wght@0,500;0,600;0,700;1,400;1,600&family=Space+Grotesk:wght@600;700&display=swap');

:root {
  /* Color Palette - Warm Ivory, Charcoal, Japanese Vermilion & Indigo */
  --bg-base: #fbfbfa;
  --bg-surface: #ffffff;
  --bg-card: #ffffff;
  --bg-card-hover: #ffffff;
  --bg-glass: rgba(251, 251, 250, 0.92);
  --bg-code: #18181b;

  --border-subtle: #e4e4e7;
  --border-strong: #d4d4d8;
  --border-vermilion: rgba(220, 38, 38, 0.25);
  --border-indigo: rgba(37, 99, 235, 0.25);

  --accent-vermilion: #dc2626;
  --accent-indigo: #2563eb;
  --accent-amber: #d97706;

  --text-primary: #18181b;
  --text-secondary: #52525b;
  --text-muted: #71717a;
  --text-vermilion: #dc2626;
  --text-indigo: #2563eb;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-serif: 'Lora', Georgia, 'Times New Roman', serif;
  --font-display: 'Space Grotesk', var(--font-sans);
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  /* Spacing & Shadows */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;

  --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.04), 0 4px 12px rgba(0, 0, 0, 0.03);
  --shadow-card-hover: 0 4px 6px -1px rgba(0, 0, 0, 0.06), 0 12px 24px -4px rgba(0, 0, 0, 0.08);
  --transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  background-color: var(--bg-base);
  color: var(--text-primary);
}

body {
  font-family: var(--font-sans);
  line-height: 1.7;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-color: var(--bg-base);
  color: var(--text-primary);
  overflow-x: hidden;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-serif);
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.3;
  letter-spacing: -0.01em;
}

p {
  margin-bottom: 1.25rem;
  color: var(--text-secondary);
}

a {
  color: var(--accent-indigo);
  text-decoration: none;
  transition: var(--transition);
}

a:hover {
  color: #1d4ed8;
  text-decoration: underline;
}

code, pre, .mono {
  font-family: var(--font-mono);
}

/* Container */
.container {
  width: 100%;
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header & Sticky Nav */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-subtle);
  padding: 0.85rem 0;
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  text-decoration: none !important;
}

.brand-badge {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 700;
  color: #ffffff;
  background: var(--text-primary);
  padding: 0.25rem 0.65rem;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  gap: 0.45rem;
  letter-spacing: 0.05em;
}

.brand-badge::before {
  content: '';
  display: inline-block;
  width: 6px;
  height: 6px;
  background-color: var(--accent-vermilion);
  border-radius: 50%;
}

.brand-text {
  display: flex;
  flex-direction: column;
}

.brand-name {
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: 0.02em;
}

.brand-tagline {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--text-muted);
}

.nav-menu {
  display: flex;
  align-items: center;
  list-style: none;
  gap: 0.25rem;
}

.nav-link {
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
  padding: 0.45rem 0.85rem;
  border-radius: var(--radius-sm);
  transition: var(--transition);
  text-decoration: none !important;
  border: 1px solid transparent;
}

.nav-link:hover {
  color: var(--text-primary);
  background: rgba(0, 0, 0, 0.04);
}

.nav-link.active {
  color: var(--text-primary);
  font-weight: 600;
  background: #ffffff;
  border-color: var(--border-subtle);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
}

.mobile-toggle {
  display: none;
  background: #ffffff;
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  padding: 0.4rem 0.6rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
}

.mobile-toggle svg {
  width: 22px;
  height: 22px;
}

/* Hero Section */
.hero {
  padding: 4.5rem 0 3rem;
  text-align: center;
}

.hero-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-secondary);
  background: #ffffff;
  border: 1px solid var(--border-subtle);
  padding: 0.35rem 1rem;
  border-radius: var(--radius-full);
  margin-bottom: 1.5rem;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
}

.hero-title {
  font-size: clamp(2.3rem, 5vw, 3.6rem);
  font-weight: 700;
  margin-bottom: 1.25rem;
  color: var(--text-primary);
}

.hero-subtitle {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 680px;
  margin: 0 auto 2.5rem;
  line-height: 1.75;
}

/* Philosophy Banner (Ziran / Self-So) */
.philosophy-banner {
  background: #ffffff;
  border: 1px solid var(--border-subtle);
  border-left: 4px solid var(--accent-vermilion);
  border-radius: var(--radius-md);
  padding: 2.25rem;
  margin: 2rem 0 3.5rem;
  position: relative;
  overflow: hidden;
  box-shadow: var(--shadow-card);
}

.philosophy-banner::before {
  content: '自然';
  position: absolute;
  right: 1.5rem;
  bottom: -0.6rem;
  font-size: 7.5rem;
  font-weight: 900;
  color: rgba(0, 0, 0, 0.03);
  pointer-events: none;
  user-select: none;
}

.philosophy-heading {
  font-size: 1.4rem;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.philosophy-text {
  font-size: 1.05rem;
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: 0;
}

/* Cards & Grid */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 1.5rem;
  margin-bottom: 3rem;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 2rem;
  transition: var(--transition);
  box-shadow: var(--shadow-card);
  display: flex;
  flex-direction: column;
}

.card:hover {
  border-color: var(--border-strong);
  transform: translateY(-2px);
  box-shadow: var(--shadow-card-hover);
}

.card-tag {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  color: var(--accent-vermilion);
  letter-spacing: 0.08em;
  margin-bottom: 0.75rem;
}

.card-title {
  font-size: 1.4rem;
  margin-bottom: 0.75rem;
}

.card-desc {
  color: var(--text-secondary);
  font-size: 0.96rem;
  line-height: 1.7;
  margin-bottom: 1.75rem;
  flex-grow: 1;
}

/* Terminal & Spec Box */
.terminal-box {
  background: var(--bg-code);
  border-radius: var(--radius-md);
  overflow: hidden;
  font-family: var(--font-mono);
  margin: 1.5rem 0 2.5rem;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
}

.terminal-header {
  background: rgba(255, 255, 255, 0.06);
  padding: 0.65rem 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

.terminal-dots {
  display: flex;
  gap: 6px;
}

.terminal-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

.dot-red { background: #ef4444; }
.dot-yellow { background: #f59e0b; }
.dot-green { background: #10b981; }

.terminal-title {
  font-size: 0.78rem;
  color: #a1a1aa;
}

.terminal-body {
  padding: 1.25rem 1.5rem;
  font-size: 0.88rem;
  line-height: 1.8;
  color: #d4d4d8;
}

.terminal-line {
  display: flex;
  gap: 0.85rem;
  margin-bottom: 0.35rem;
}

.terminal-prompt {
  color: #34d399;
  user-select: none;
}

/* Timeline */
.timeline {
  position: relative;
  padding-left: 2rem;
  margin: 2.5rem 0;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: var(--border-subtle);
}

.timeline-item {
  position: relative;
  margin-bottom: 2rem;
}

.timeline-dot {
  position: absolute;
  left: -2rem;
  top: 4px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: #ffffff;
  border: 3px solid var(--accent-vermilion);
}

.timeline-date {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--accent-vermilion);
  margin-bottom: 0.35rem;
}

.timeline-content {
  background: #ffffff;
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  box-shadow: var(--shadow-card);
}

.timeline-content p:last-child {
  margin-bottom: 0;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  padding: 0.65rem 1.35rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none !important;
}

.btn-primary {
  background: var(--text-primary);
  color: #ffffff;
  border: 1px solid var(--text-primary);
}

.btn-primary:hover {
  background: #27272a;
  border-color: #27272a;
  color: #ffffff;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.btn-outline {
  background: #ffffff;
  color: var(--text-primary);
  border: 1px solid var(--border-strong);
}

.btn-outline:hover {
  background: #f4f4f5;
  border-color: #a1a1aa;
}

/* Badges */
.badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.25rem 0.65rem;
  border-radius: var(--radius-sm);
  background: #f4f4f5;
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
}

.badge-vermilion {
  background: rgba(220, 38, 38, 0.08);
  border-color: var(--border-vermilion);
  color: var(--text-vermilion);
}

.badge-indigo {
  background: rgba(37, 99, 235, 0.08);
  border-color: var(--border-indigo);
  color: var(--text-indigo);
}

/* Footer */
.site-footer {
  margin-top: auto;
  border-top: 1px solid var(--border-subtle);
  background: #ffffff;
  padding: 3.5rem 0 2rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 2.5rem;
  margin-bottom: 2.5rem;
}

.footer-brand h4 {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  margin-bottom: 0.5rem;
}

.footer-brand p {
  font-size: 0.92rem;
  color: var(--text-muted);
}

.footer-col h5 {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  text-transform: uppercase;
  color: var(--text-primary);
  margin-bottom: 1rem;
  letter-spacing: 0.05em;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.footer-links a {
  font-size: 0.9rem;
  color: var(--text-secondary);
  text-decoration: none;
  transition: var(--transition);
}

.footer-links a:hover {
  color: var(--accent-vermilion);
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 1.75rem;
  border-top: 1px solid var(--border-subtle);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* Responsive */
@media (max-width: 860px) {
  .nav-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: #ffffff;
    flex-direction: column;
    padding: 1.25rem 1.5rem;
    border-bottom: 1px solid var(--border-subtle);
    gap: 0.5rem;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
  }

  .nav-menu.open {
    display: flex;
  }

  .mobile-toggle {
    display: block;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .footer-bottom {
    flex-direction: column;
    gap: 0.75rem;
    text-align: center;
  }
}