/* ==========================================================================
   Base Styles & Reset
   ========================================================================== */

:root {
  /* Color Palette */
  --color-primary: #1e3a5f;
  --color-primary-light: #2b5c8f;
  --color-primary-dark: #132742;
  --color-secondary: #0284c7;
  --color-accent: #0ea5e9;
  
  --color-text-main: #1e293b;
  --color-text-muted: #64748b;
  --color-text-light: #94a3b8;
  --color-text-white: #ffffff;

  --color-bg-white: #ffffff;
  --color-bg-light: #f8fafc;
  --color-bg-muted: #f1f5f9;
  --color-bg-dark: #0f172a;

  --color-border: #e2e8f0;
  --color-border-dark: #cbd5e1;

  /* Typography */
  --font-family-base: "Helvetica Neue", Arial, "Hiragino Kaku Gothic ProN", "Hiragino Sans", Meiryo, sans-serif;
  --font-size-base: 1rem;      /* 16px */
  --font-size-sm: 0.875rem;    /* 14px */
  --font-size-lg: 1.125rem;    /* 18px */
  --font-size-xl: 1.25rem;     /* 20px */
  --font-size-2xl: 1.5rem;     /* 24px */
  --font-size-3xl: 1.875rem;   /* 30px */
  --font-size-4xl: 2.25rem;    /* 36px */
  --line-height-base: 1.75;
  --line-height-heading: 1.4;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4.5rem;

  /* Layout */
  --container-max-width: 1080px;
  --header-height: 72px;

  /* Shadows & Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-full: 9999px;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);

  /* Transitions */
  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;
}

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

html {
  font-size: 100%;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-family-base);
  font-size: var(--font-size-base);
  line-height: var(--line-height-base);
  color: var(--color-text-main);
  background-color: var(--color-bg-white);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

img {
  max-width: 100%;
  height: auto;
  vertical-align: middle;
  display: inline-block;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast), opacity var(--transition-fast);
}

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

ul, ol {
  list-style: none;
}

button, input, textarea, select {
  font: inherit;
  color: inherit;
}

button {
  cursor: pointer;
  border: none;
  background: none;
}

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