/* ============================================
   Product Impossible — Minimal, mobile-first CSS
   ============================================ */

/* --- Custom Properties --- */
:root {
  --color-bg: #ffffff;
  --color-text: #1a1a1a;
  --color-text-muted: #666666;
  --color-accent: #2563eb;
  --color-accent-hover: #1d4ed8;
  --color-border: #e5e5e5;
  --color-surface: #f9fafb;
  --color-badge-bg: #f0f0f0;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, monospace;

  --max-width: 720px;
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --spacing-2xl: 4rem;
}

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

/* --- Base --- */
html {
  -webkit-text-size-adjust: 100%;
  line-height: 1.6;
}

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

main {
  flex: 1;
}

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

a:hover {
  text-decoration: underline;
}

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

/* --- Container --- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

/* --- Header --- */
.site-header {
  border-bottom: 1px solid var(--color-border);
  padding: var(--spacing-md) 0;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-logo {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--color-text);
  text-decoration: none;
  letter-spacing: -0.02em;
}

.site-logo:hover {
  text-decoration: none;
}

.site-nav {
  display: none;
  gap: var(--spacing-lg);
}

.site-nav a {
  color: var(--color-text-muted);
  font-size: 0.875rem;
  text-decoration: none;
}

.site-nav a:hover {
  color: var(--color-text);
}

.nav-toggle {
  display: flex;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--spacing-xs);
}

.nav-toggle span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--color-text);
  transition: transform 0.2s;
}

/* --- Footer --- */
.site-footer {
  border-top: 1px solid var(--color-border);
  padding: var(--spacing-lg) 0;
  margin-top: var(--spacing-2xl);
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm) var(--spacing-md);
  margin-bottom: var(--spacing-sm);
}

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

.footer-nav a:hover {
  color: var(--color-text);
}

.copyright {
  color: var(--color-text-muted);
  font-size: 0.8125rem;
}

/* --- Hero --- */
.hero {
  padding: var(--spacing-2xl) 0 var(--spacing-xl);
}

.hero h1 {
  font-size: 2rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: var(--spacing-md);
}

.hero .tagline {
  font-size: 1.125rem;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-sm);
}

.hero .subtitle {
  color: var(--color-text-muted);
  font-size: 0.9375rem;
  line-height: 1.6;
  margin-bottom: var(--spacing-lg);
}

.hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
}

/* --- Buttons --- */
.btn {
  display: inline-block;
  padding: 0.625rem 1.25rem;
  border-radius: 6px;
  font-size: 0.9375rem;
  font-weight: 500;
  text-decoration: none;
  transition: background 0.15s, color 0.15s;
}

.btn:hover {
  text-decoration: none;
}

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

.btn-primary:hover {
  background: #333;
}

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

.btn-secondary:hover {
  background: var(--color-border);
}

/* --- Sections --- */
.section {
  padding: var(--spacing-xl) 0;
  border-top: 1px solid var(--color-border);
}

.section-title {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: var(--spacing-xs);
  letter-spacing: -0.02em;
}

.section-subtitle {
  color: var(--color-text-muted);
  font-size: 0.9375rem;
  margin-bottom: var(--spacing-lg);
}

.section-date {
  color: var(--color-text-muted);
  font-size: 0.875rem;
}

/* --- Digest Items --- */
.digest-list {
  list-style: none;
  counter-reset: digest;
}

.digest-item {
  counter-increment: digest;
  padding: var(--spacing-md) 0;
  border-bottom: 1px solid var(--color-border);
}

.digest-item:last-child {
  border-bottom: none;
}

.digest-item-header {
  display: flex;
  align-items: baseline;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-xs);
}

.digest-item-number {
  font-size: 0.8125rem;
  font-weight: 700;
  color: var(--color-text-muted);
  min-width: 1.5em;
}

.digest-item-number::before {
  content: counter(digest) ".";
}

.digest-item-name {
  font-weight: 600;
  font-size: 1rem;
}

.digest-item-name a {
  color: var(--color-text);
}

.digest-item-name a:hover {
  color: var(--color-accent);
}

.digest-item-desc {
  color: var(--color-text-muted);
  font-size: 0.9375rem;
  margin-left: calc(1.5em + var(--spacing-sm));
  margin-bottom: var(--spacing-xs);
}

.digest-item-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-xs);
  margin-left: calc(1.5em + var(--spacing-sm));
}

/* --- Badges --- */
.badge {
  display: inline-block;
  font-size: 0.75rem;
  padding: 0.125rem 0.5rem;
  border-radius: 3px;
  background: var(--color-badge-bg);
  color: var(--color-text-muted);
  font-weight: 500;
}

.badge-source {
  background: #e8f0fe;
  color: #1a56db;
}

.badge-category {
  background: #f0fdf4;
  color: #15803d;
}

/* --- See All Link --- */
.see-all {
  display: inline-block;
  margin-top: var(--spacing-md);
  font-weight: 500;
  font-size: 0.9375rem;
}

/* --- Blog List --- */
.blog-list {
  list-style: none;
}

.blog-item {
  padding: var(--spacing-md) 0;
  border-bottom: 1px solid var(--color-border);
}

.blog-item:last-child {
  border-bottom: none;
}

.blog-item-title {
  font-weight: 600;
}

.blog-item-title a {
  color: var(--color-text);
}

.blog-item-title a:hover {
  color: var(--color-accent);
}

.blog-item-meta {
  color: var(--color-text-muted);
  font-size: 0.8125rem;
  margin-top: var(--spacing-xs);
}

/* --- Subscribe CTA --- */
.subscribe-section {
  background: var(--color-surface);
  border-radius: 8px;
  padding: var(--spacing-lg);
  margin: var(--spacing-xl) 0;
}

.subscribe-section h2 {
  font-size: 1.125rem;
  font-weight: 700;
  margin-bottom: var(--spacing-sm);
}

.subscribe-section p {
  color: var(--color-text-muted);
  font-size: 0.9375rem;
  margin-bottom: var(--spacing-md);
}

/* --- Trust Line --- */
.trust-line {
  padding: var(--spacing-lg) 0;
  color: var(--color-text-muted);
  font-size: 0.875rem;
  line-height: 1.7;
}

/* --- Page Content (markdown) --- */
.page-content {
  padding: var(--spacing-xl) 0;
}

.page-content h1 {
  font-size: 1.75rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: var(--spacing-lg);
}

.page-content h2 {
  font-size: 1.375rem;
  font-weight: 700;
  margin-top: var(--spacing-xl);
  margin-bottom: var(--spacing-md);
}

.page-content h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-top: var(--spacing-lg);
  margin-bottom: var(--spacing-sm);
}

.page-content p {
  margin-bottom: var(--spacing-md);
}

.page-content ul, .page-content ol {
  margin-bottom: var(--spacing-md);
  padding-left: var(--spacing-lg);
}

.page-content li {
  margin-bottom: var(--spacing-xs);
}

.page-content blockquote {
  border-left: 3px solid var(--color-border);
  padding-left: var(--spacing-md);
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-md);
}

/* --- Review Post --- */
.review-header {
  padding: var(--spacing-xl) 0 var(--spacing-md);
}

.review-header h1 {
  font-size: 1.75rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: var(--spacing-sm);
}

.review-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  align-items: center;
  color: var(--color-text-muted);
  font-size: 0.875rem;
}

.review-meta .separator {
  color: var(--color-border);
}

.affiliate-disclosure {
  font-style: italic;
  color: var(--color-text-muted);
  font-size: 0.875rem;
  padding: var(--spacing-md) 0;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: var(--spacing-lg);
}

/* --- Weekly Digest Page --- */
.digest-header {
  padding: var(--spacing-xl) 0 var(--spacing-md);
}

.digest-header h1 {
  font-size: 1.75rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: var(--spacing-xs);
}

.digest-header .date-range {
  color: var(--color-text-muted);
  font-size: 0.9375rem;
}

/* --- Archive Pages --- */
.archive-header {
  padding: var(--spacing-xl) 0 var(--spacing-md);
}

.archive-header h1 {
  font-size: 1.75rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: var(--spacing-xs);
}

.archive-header p {
  color: var(--color-text-muted);
}

.archive-list {
  list-style: none;
}

.archive-item {
  padding: var(--spacing-md) 0;
  border-bottom: 1px solid var(--color-border);
}

.archive-item:last-child {
  border-bottom: none;
}

.archive-item a {
  font-weight: 600;
  color: var(--color-text);
}

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

.archive-item .date {
  color: var(--color-text-muted);
  font-size: 0.8125rem;
  display: block;
  margin-top: var(--spacing-xs);
}

/* --- 404 --- */
.not-found {
  text-align: center;
  padding: var(--spacing-2xl) 0;
}

.not-found h1 {
  font-size: 3rem;
  font-weight: 800;
  margin-bottom: var(--spacing-sm);
}

.not-found p {
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-lg);
}

/* --- Responsive --- */
@media (min-width: 640px) {
  .site-nav {
    display: flex;
  }

  .nav-toggle {
    display: none;
  }

  .hero h1 {
    font-size: 2.5rem;
  }
}

/* --- Simple mobile nav toggle (no JS dependency, CSS-only) --- */
.nav-toggle[aria-expanded="true"] + .site-nav {
  display: flex;
}

/* Mobile nav: stack vertically when toggled */
@media (max-width: 639px) {
  .header-inner {
    flex-wrap: wrap;
  }

  .site-nav {
    flex-direction: column;
    width: 100%;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) 0;
  }
}