/* ============================================================
   BASE.CSS — CSS Custom Properties, Reset, Typography
   ============================================================ */

/* --- Custom Properties --- */
:root {
  /* Colors — Dark Gen Z Theme (Global) */
  --color-primary:       #08080f;
  --color-primary-hover: #0f0f1a;
  --color-accent:        #e94560;
  --color-accent-hover:  #c73652;
  --color-accent2:       #7c3aed;
  --color-grade-a:       #10b981;
  --color-grade-a-bg:    rgba(16,185,129,0.12);
  --color-grade-b:       #f59e0b;
  --color-grade-b-bg:    rgba(245,158,11,0.12);
  --color-text:          #f0f0ff;
  --color-text-light:    #c8cde0;
  --color-muted:         #8892a4;
  --color-border:        rgba(255,255,255,0.07);
  --color-border-dark:   rgba(255,255,255,0.12);
  --color-surface:       #0f0f1a;
  --color-white:         #ffffff;
  --color-black:         #000000;
  --color-success:       #10b981;
  --color-warning:       #f59e0b;
  --color-danger:        #ef4444;
  --color-info:          #3b82f6;

  /* Spacing */
  --spacing-xs:  0.25rem;
  --spacing-sm:  0.5rem;
  --spacing-md:  1rem;
  --spacing-lg:  1.5rem;
  --spacing-xl:  2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 5rem;

  /* Border radius */
  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 1rem;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'Fira Code', 'Cascadia Code', monospace;
  --text-xs:   0.75rem;
  --text-sm:   0.875rem;
  --text-base: 1rem;
  --text-lg:   1.125rem;
  --text-xl:   1.25rem;
  --text-2xl:  1.5rem;
  --text-3xl:  1.875rem;
  --text-4xl:  2.25rem;
  --text-5xl:  3rem;
  --leading-tight:  1.25;
  --leading-snug:   1.375;
  --leading-normal: 1.5;
  --leading-relaxed:1.625;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;

  /* Z-index scale */
  --z-dropdown: 100;
  --z-sticky:   200;
  --z-modal:    300;
  --z-toast:    400;
}

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

/* --- Base HTML --- */
html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--color-text);
  background-color: var(--color-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-sans);
  font-weight: 700;
  line-height: var(--leading-tight);
  color: var(--color-white);
}

h1 { font-size: var(--text-4xl); }
h2 { font-size: var(--text-3xl); }
h3 { font-size: var(--text-2xl); }
h4 { font-size: var(--text-xl); }
h5 { font-size: var(--text-lg); }
h6 { font-size: var(--text-base); }

p {
  line-height: var(--leading-relaxed);
  color: var(--color-text-light);
}

p + p {
  margin-top: var(--spacing-md);
}

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

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

ul, ol {
  list-style: none;
}

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

table {
  border-collapse: collapse;
  width: 100%;
}

input,
textarea,
select,
button {
  font-family: inherit;
  font-size: inherit;
}

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

/* --- Focus Styles (Accessibility) --- */
:focus-visible {
  outline: 3px solid var(--color-accent);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* --- Screen Reader Only --- */
.screen-reader-text {
  clip: rect(1px, 1px, 1px, 1px);
  clip-path: inset(50%);
  height: 1px;
  margin: -1px;
  overflow: hidden;
  padding: 0;
  position: absolute;
  width: 1px;
  word-wrap: normal !important;
}

.screen-reader-text:focus {
  background-color: var(--color-white);
  clip: auto !important;
  clip-path: none;
  color: var(--color-primary);
  display: block;
  font-size: var(--text-base);
  font-weight: 700;
  height: auto;
  left: 5px;
  line-height: normal;
  padding: 15px 23px 14px;
  text-decoration: none;
  top: 5px;
  width: auto;
  z-index: 100000;
}

/* --- Clearfix --- */
.clearfix::after {
  content: '';
  display: table;
  clear: both;
}

/* --- Utility --- */
.sr-only { composes: screen-reader-text; }
.hidden  { display: none !important; }
.visually-hidden { visibility: hidden; }