/* ========================================
   TO THINK STRANGELY - Base Design System
   ======================================== */

/* --- Variables --- */
:root {
  --color-white:      #FFFFFF;
  --color-bg-section: #F7F7F7;
  --color-bg-card:    #EFEFEF;
  --color-black:      #0A0A0A;
  --color-dark:       #1A1A1A;
  --color-text-primary:  #111111;
  --color-text-body:     #555555;
  --color-text-muted:    #999999;
  --color-border:        #D0D0D0;
  --color-accent:        #C8FF00;

  --font-sans:   'Inter', 'Noto Sans JP', sans-serif;
  --font-accent: 'Space Grotesk', sans-serif;

  --space-section: 120px;
  --space-block:    64px;
  --space-element:  32px;

  --radius-sm:  4px;
  --radius-md:  8px;
  --radius-lg: 16px;

  --transition: 0.25s ease;
}

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

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: var(--font-sans);
  font-weight: 400;
  color: var(--color-text-body);
  background-color: var(--color-white);
  line-height: 1.8;
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-sans);
  font-weight: 300;
  color: var(--color-text-primary);
  line-height: 1.3;
  letter-spacing: -0.02em;
}

h1 { font-size: clamp(2.5rem, 6vw, 5rem); }
h2 { font-size: clamp(1.8rem, 4vw, 3rem); }
h3 { font-size: clamp(1.3rem, 2.5vw, 1.8rem); }
h4 { font-size: 1.2rem; }

p {
  font-size: 1rem;
  line-height: 1.9;
  color: var(--color-text-body);
}

/* 英字アクセント見出し */
.en-label {
  font-family: var(--font-accent);
  font-weight: 300;
  font-size: 0.75rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-text-muted);
}

/* --- Layout --- */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 40px;
}

@media (max-width: 768px) {
  .container {
    padding: 0 20px;
  }
}

/* --- Section --- */
.section {
  padding: var(--space-section) 0;
}

.section--gray {
  background-color: var(--color-bg-section);
}

.section--dark {
  background-color: var(--color-black);
  color: var(--color-white);
}

.section--dark h1,
.section--dark h2,
.section--dark h3,
.section--dark h4 {
  color: var(--color-white);
}

.section--dark p {
  color: var(--color-text-muted);
}

/* --- Button --- */
.btn {
  display: inline-block;
  font-family: var(--font-accent);
  font-size: 0.85rem;
  font-weight: 400;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  text-decoration: none;
  padding: 16px 40px;
  border-radius: var(--radius-sm);
  transition: var(--transition);
  cursor: pointer;
  border: none;
}

/* Primary CTA */
.btn--primary {
  background-color: var(--color-black);
  color: var(--color-white);
}

.btn--primary:hover {
  background-color: var(--color-accent);
  color: var(--color-black);
}

/* Outline */
.btn--outline {
  background-color: transparent;
  color: var(--color-black);
  border: 1px solid var(--color-black);
}

.btn--outline:hover {
  background-color: var(--color-black);
  color: var(--color-white);
}

/* Accent */
.btn--accent {
  background-color: var(--color-accent);
  color: var(--color-black);
}

.btn--accent:hover {
  background-color: var(--color-black);
  color: var(--color-white);
}

/* --- Card --- */
.card {
  background-color: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 40px;
  transition: var(--transition);
}

.card:hover {
  border-color: var(--color-black);
  transform: translateY(-4px);
}

/* --- Divider --- */
.divider {
  width: 40px;
  height: 1px;
  background-color: var(--color-black);
  margin: 24px 0;
}

/* --- Link --- */
a {
  color: var(--color-text-primary);
  text-decoration: none;
  transition: var(--transition);
}

a:hover {
  color: var(--color-text-muted);
}

/* --- Image --- */
img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* --- Utility --- */
.text-muted  { color: var(--color-text-muted); }
.text-accent { color: var(--color-accent); }
.text-center { text-align: center; }
.mt-sm { margin-top: var(--space-element); }
.mt-md { margin-top: var(--space-block); }
.mt-lg { margin-top: var(--space-section); }