/* =============================================
   CSS 重置和基础样式
   ============================================= */

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

/* Remove default margin and padding */
html, body, div, span, h1, h2, h3, h4, h5, h6, p, 
blockquote, pre, a, button, input, select, textarea,
ul, ol, li, table, tr, td, th {
  margin: 0;
  padding: 0;
}

/* Set base font */
html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  font-size: 14px;
  line-height: 1.6;
  color: var(--text);
  background: var(--surface);
  min-height: 100vh;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.3;
  color: var(--text);
}

h1 { font-size: 2rem; }
h2 { font-size: 1.5rem; }
h3 { font-size: 1.25rem; }
h4 { font-size: 1.125rem; }
h5 { font-size: 1rem; }
h6 { font-size: 0.875rem; }

p {
  margin-bottom: 1em;
}

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

a:hover {
  color: var(--primary-hover);
  text-decoration: underline;
}

/* Lists */
ul, ol {
  list-style: none;
}

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

/* Tables */
table {
  border-collapse: collapse;
  width: 100%;
}

/* Form elements */
input, button, select, textarea {
  font-family: inherit;
  font-size: inherit;
  line-height: inherit;
}

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

input, select, textarea {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 10px 14px;
  transition: var(--transition-fast);
}

input:focus, select:focus, textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}

input::placeholder, textarea::placeholder {
  color: var(--text-muted);
}

/* Scrollbar styling */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

/* Selection */
::selection {
  background: var(--primary-light);
  color: var(--primary);
}

/* Focus visible */
:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

/* Screen reader only */
.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;
}