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

html {
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font-sans);
  font-size: var(--text-base);
  font-weight: var(--weight-regular);
  line-height: var(--leading-normal);
  color: var(--text);
  background-color: var(--bg);
  transition: background-color var(--transition-slow) var(--easing-smooth),
              color var(--transition-slow) var(--easing-smooth);
}

h1, h2, h3, h4, h5, h6 {
  margin: 0;
  font-weight: var(--weight-semibold);
  line-height: var(--leading-tight);
  color: var(--text-strong);
  letter-spacing: -0.015em;
}

h1 { font-size: var(--text-3xl); letter-spacing: -0.025em; }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }
h5 { font-size: var(--text-md); }
h6 { font-size: var(--text-sm); text-transform: uppercase; letter-spacing: 0.08em; color: var(--text-muted); }

p { margin: 0; }

a {
  color: var(--accent);
  text-decoration: none;
  transition: color var(--transition-fast) var(--easing-smooth);
}
a:hover { color: var(--accent-strong); }
a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: var(--radius-xs);
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  color: inherit;
  padding: 0;
}
button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

img, svg, video {
  max-width: 100%;
  display: block;
}

input, textarea, select {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
}
input:focus-visible,
textarea:focus-visible,
select:focus-visible {
  outline: none;
}

::selection {
  background-color: var(--accent);
  color: var(--text-invert);
}

::-webkit-scrollbar {
  width: 10px;
  height: 10px;
}
::-webkit-scrollbar-track {
  background: var(--bg-subtle);
}
::-webkit-scrollbar-thumb {
  background: var(--border-strong);
  border-radius: var(--radius-full);
  border: 2px solid var(--bg-subtle);
  transition: background var(--transition-fast);
}
::-webkit-scrollbar-thumb:hover {
  background: var(--text-soft);
}
* {
  scrollbar-width: thin;
  scrollbar-color: var(--border-strong) var(--bg-subtle);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.text-muted { color: var(--text-muted); }
.text-soft  { color: var(--text-soft); }
.text-strong { color: var(--text-strong); }
.text-accent { color: var(--accent); }

.bg-subtle { background-color: var(--bg-subtle); }
.bg-muted  { background-color: var(--bg-muted); }

.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  color: var(--text-muted);
  background: transparent;
  border: 1px solid transparent;
  transition: color var(--transition-fast) var(--easing-smooth),
              background-color var(--transition-fast) var(--easing-smooth),
              border-color var(--transition-fast) var(--easing-smooth),
              transform var(--transition-fast) var(--easing-spring);
}
.theme-toggle:hover {
  color: var(--accent);
  background: var(--bg-subtle);
  border-color: var(--border);
}
.theme-toggle:active { transform: scale(0.94); }
.theme-toggle i {
  font-size: 0.95rem;
  transition: transform var(--transition-base) var(--easing-spring);
}
.theme-toggle:hover i { transform: rotate(-15deg); }

.theme-toggle--floating {
  position: fixed;
  top: var(--space-4);
  right: var(--space-4);
  width: 44px;
  height: 44px;
  background: var(--glass-bg);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border: 1px solid var(--glass-border);
  box-shadow: var(--shadow-md);
  z-index: 100;
}
.theme-toggle--floating:hover {
  background: var(--surface);
  border-color: var(--accent);
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}