/* ============================================================
   Main — Reset, Typography, Layout Grid
   ============================================================ */

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

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

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background-color var(--transition-base), color var(--transition-base);
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  line-height: 1.25;
  font-weight: 700;
  color: var(--color-text);
}

h1 { font-size: clamp(1.75rem, 4vw, 2.5rem); }
h2 { font-size: clamp(1.35rem, 3vw, 1.875rem); }
h3 { font-size: clamp(1.1rem, 2vw, 1.5rem); }

p { margin-bottom: 1rem; }

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

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

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

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

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

/* --- Buttons --- */
button {
  font-family: inherit;
  font-size: inherit;
  cursor: pointer;
  border: none;
  background: none;
  color: inherit;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.625rem 1.25rem;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.9375rem;
  line-height: 1.4;
  transition: all var(--transition-fast);
  white-space: nowrap;
  user-select: none;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-primary {
  background-color: var(--color-primary);
  color: var(--color-primary-text);
}

.btn-primary:hover:not(:disabled) {
  background-color: var(--color-primary-hover);
  text-decoration: none;
}

.btn-secondary {
  background-color: var(--color-bg-tertiary);
  color: var(--color-text);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover:not(:disabled) {
  background-color: var(--color-border);
  text-decoration: none;
}

.btn-ghost {
  background: transparent;
  color: var(--color-text-secondary);
}

.btn-ghost:hover:not(:disabled) {
  background-color: var(--color-bg-tertiary);
  color: var(--color-text);
  text-decoration: none;
}

.btn-icon {
  width: 40px;
  height: 40px;
  padding: 0;
  border-radius: var(--radius-full);
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.btn-icon svg {
  width: 20px;
  height: 20px;
}

/* --- Form elements --- */
input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  border-radius: 3px;
  background: var(--color-bg-tertiary);
  outline: none;
  cursor: pointer;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--color-primary);
  border: 2px solid var(--color-bg);
  box-shadow: var(--shadow-sm);
  cursor: pointer;
}

input[type="range"]::-moz-range-thumb {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--color-primary);
  border: 2px solid var(--color-bg);
  box-shadow: var(--shadow-sm);
  cursor: pointer;
}

select {
  font-family: inherit;
  font-size: 0.9375rem;
  padding: 0.5rem 2rem 0.5rem 0.75rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  background-color: var(--color-bg);
  color: var(--color-text);
  cursor: pointer;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%235a6170' stroke-width='2'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.75rem center;
  transition: border-color var(--transition-fast);
}

select:focus {
  border-color: var(--color-primary);
  outline: none;
}

/* --- Layout --- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-height);
  background-color: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  padding: 0 1rem;
  transition: background-color var(--transition-base);
}

.header-inner {
  max-width: var(--max-width);
  width: 100%;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--color-text);
  text-decoration: none;
}

.site-logo:hover {
  text-decoration: none;
  color: var(--color-primary);
}

.site-logo svg {
  width: 28px;
  height: 28px;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.site-main {
  flex: 1;
  max-width: var(--max-width);
  width: 100%;
  margin: 0 auto;
  padding: 1.5rem 1rem 2rem;
}

.site-footer {
  background-color: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  padding: 1.5rem 1rem;
  text-align: center;
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  transition: background-color var(--transition-base);
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 1rem 2rem;
}

.footer-links {
  display: flex;
  gap: 1.5rem;
  list-style: none;
}

.footer-links a {
  color: var(--color-text-secondary);
  font-size: 0.875rem;
}

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

/* --- Ad containers --- */
.ad-container {
  min-height: 90px;
  background-color: var(--color-bg-secondary);
  border: 1px dashed var(--color-border);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  transition: background-color var(--transition-base);
}

.ad-container::before {
  content: 'Advertisement';
  font-size: 0.75rem;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.ad-banner {
  min-height: 90px;
  width: 100%;
  max-width: 970px;
  margin: 0 auto;
}

.ad-sidebar {
  min-height: 250px;
  min-width: 160px;
}

.ad-inline {
  min-height: 90px;
  margin: 2rem 0;
}

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

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1rem;
}

.text-center { text-align: center; }
.text-muted  { color: var(--color-text-secondary); }
.text-sm     { font-size: 0.875rem; }
.text-xs     { font-size: 0.75rem; }
.font-mono   { font-family: var(--font-mono); }
.font-bold   { font-weight: 700; }

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }

.flex       { display: flex; }
.flex-col   { flex-direction: column; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-1 { gap: 0.5rem; }
.gap-2 { gap: 1rem; }
.gap-3 { gap: 1.5rem; }