/* ============================================================
   Multi-Protocol Flow Executor — Public Website Styles
   ============================================================ */

/* --- Design Tokens --- */
:root {
  --color-primary: #0ea5e9;
  --color-primary-hover: #38bdf8;
  --color-secondary: #14b8a6;
  --color-secondary-hover: #2dd4bf;
  --color-accent: #8b5cf6;

  --color-bg: #0f172a;
  --color-surface: #1e293b;
  --color-surface-hover: #334155;
  --color-border: #334155;
  --color-text: #f8fafc;
  --color-text-muted: #94a3b8;
  --color-text-dim: #64748b;
  --color-success: #22c55e;
  --color-warning: #eab308;
  --color-error: #ef4444;

  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;

  --spacing-1: 4px;
  --spacing-2: 8px;
  --spacing-3: 12px;
  --spacing-4: 16px;
  --spacing-5: 20px;
  --spacing-6: 24px;
  --spacing-8: 32px;
  --spacing-10: 40px;
  --spacing-12: 48px;
  --spacing-16: 64px;
  --spacing-20: 80px;

  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;

  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);

  --transition: 200ms ease;
}

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

html {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

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

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

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

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

/* --- Typography --- */
h1, h2, h3, h4 {
  line-height: 1.2;
  font-weight: 700;
}

h1 {
  font-size: clamp(2rem, 5vw, 3.5rem);
  letter-spacing: -0.02em;
}

h2 {
  font-size: clamp(1.5rem, 3vw, 2.25rem);
  margin-bottom: var(--spacing-4);
}

h3 {
  font-size: 1.25rem;
  margin-bottom: var(--spacing-2);
}

p {
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-4);
}

code {
  font-family: var(--font-mono);
  font-size: 0.875em;
}

/* --- Utility --- */
.container {
  width: 100%;
  max-width: 1024px;
  margin: 0 auto;
  padding: 0 var(--spacing-6);
}

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

/* --- Header / Nav --- */
.site-header {
  border-bottom: 1px solid var(--color-border);
  padding: var(--spacing-4) 0;
  position: sticky;
  top: 0;
  background: rgba(15, 23, 42, 0.9);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  z-index: 100;
}

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

.logo {
  display: flex;
  align-items: center;
}

.logo-img {
  height: 40px;
  width: auto;
  display: block;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--spacing-6);
  list-style: none;
}

.nav-links a {
  color: var(--color-text-muted);
  font-size: 0.9rem;
  font-weight: 500;
  transition: color var(--transition);
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-text);
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-2);
  padding: var(--spacing-3) var(--spacing-6);
  border: none;
  border-radius: var(--radius-md);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  text-decoration: none;
  line-height: 1;
}

.btn:active {
  transform: translateY(1px);
}

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

.btn-primary:hover {
  background: var(--color-primary-hover);
  color: #fff;
  box-shadow: 0 0 24px rgba(14, 165, 233, 0.35);
}

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

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

.btn-success {
  background: var(--color-secondary);
  color: #fff;
}

.btn-success:hover {
  background: var(--color-secondary-hover);
  color: #fff;
  box-shadow: 0 0 24px rgba(20, 184, 166, 0.35);
}

.btn-lg {
  padding: var(--spacing-4) var(--spacing-8);
  font-size: 1.05rem;
}

.btn-block {
  width: 100%;
  justify-content: center;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

/* --- Hero Section --- */
.hero {
  padding: var(--spacing-20) 0 var(--spacing-16);
  text-align: center;
  flex: 1;
}

.hero-tag {
  display: inline-block;
  padding: var(--spacing-1) var(--spacing-3);
  background: rgba(14, 165, 233, 0.12);
  color: var(--color-primary);
  border-radius: 9999px;
  font-size: 0.8rem;
  font-weight: 600;
  margin-bottom: var(--spacing-6);
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

.hero h1 {
  margin-bottom: var(--spacing-4);
}

.hero h1 span {
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: clamp(1rem, 2vw, 1.2rem);
  max-width: 600px;
  margin: 0 auto var(--spacing-8);
  color: var(--color-text-muted);
}

.hero-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-4);
  flex-wrap: wrap;
}

.hero-version {
  margin-top: var(--spacing-4);
  font-size: 0.85rem;
  color: var(--color-text-dim);
}

/* --- Feature Cards --- */
.features {
  padding: var(--spacing-16) 0;
}

.features h2 {
  text-align: center;
  margin-bottom: var(--spacing-12);
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-6);
}

.feature-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--spacing-8);
  transition: all var(--transition);
}

.feature-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.feature-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  margin-bottom: var(--spacing-4);
}

.feature-card h3 {
  margin-bottom: var(--spacing-2);
  font-size: 1rem;
}

.feature-card p {
  font-size: 0.9rem;
  margin-bottom: 0;
}

/* --- Download Page --- */
.download-page {
  padding: var(--spacing-12) 0;
  flex: 1;
}

.download-page h1 {
  text-align: center;
  margin-bottom: var(--spacing-8);
}

.download-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--spacing-8);
  max-width: 560px;
  margin: 0 auto var(--spacing-6);
}

.download-card h2 {
  font-size: 1.15rem;
  margin-bottom: var(--spacing-2);
}

.download-card .version-badge {
  display: inline-block;
  padding: 2px var(--spacing-2);
  background: rgba(14, 165, 233, 0.12);
  color: var(--color-primary);
  border-radius: 9999px;
  font-size: 0.8rem;
  font-weight: 600;
  margin-bottom: var(--spacing-4);
}

.download-card p {
  font-size: 0.9rem;
  margin-bottom: var(--spacing-6);
}

.download-options {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-3);
}

.download-option {
  display: flex;
  align-items: center;
  gap: var(--spacing-4);
  padding: var(--spacing-4);
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  transition: border-color var(--transition);
}

.download-option.recommended {
  border-color: var(--color-primary);
  position: relative;
}

.download-option.recommended::before {
  content: 'Recommended';
  position: absolute;
  top: -10px;
  left: var(--spacing-4);
  padding: 0 var(--spacing-2);
  background: var(--color-primary);
  color: #fff;
  font-size: 0.7rem;
  font-weight: 700;
  border-radius: var(--radius-sm);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.download-option-info {
  flex: 1;
}

.download-option-info strong {
  display: block;
  font-size: 0.95rem;
  margin-bottom: 2px;
}

.download-option-info span {
  font-size: 0.8rem;
  color: var(--color-text-dim);
}

.download-status {
  text-align: center;
  padding: var(--spacing-8);
  color: var(--color-text-dim);
}

.download-status.error {
  color: var(--color-error);
}

.download-status .spinner {
  width: 24px;
  height: 24px;
  border: 3px solid var(--color-border);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin: 0 auto var(--spacing-4);
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* --- Changelog Page --- */
.changelog-page {
  padding: var(--spacing-12) 0;
  flex: 1;
}

.changelog-page h1 {
  text-align: center;
  margin-bottom: var(--spacing-8);
}

.release-list {
  max-width: 640px;
  margin: 0 auto;
}

.release-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--spacing-6);
  margin-bottom: var(--spacing-4);
  transition: border-color var(--transition);
}

.release-card:hover {
  border-color: var(--color-primary);
}

.release-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--spacing-3);
}

.release-version {
  font-weight: 700;
  font-size: 1rem;
  color: var(--color-primary);
  font-family: var(--font-mono);
}

.release-date {
  font-size: 0.8rem;
  color: var(--color-text-dim);
}

.release-notes {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  white-space: pre-wrap;
  line-height: 1.7;
}

.release-notes ul {
  padding-left: var(--spacing-5);
  margin: var(--spacing-2) 0;
}

.release-notes li {
  margin-bottom: var(--spacing-1);
}

/* --- Footer --- */
.site-footer {
  border-top: 1px solid var(--color-border);
  padding: var(--spacing-8) 0;
  margin-top: auto;
}

.site-footer .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--spacing-4);
}

.site-footer p {
  font-size: 0.85rem;
  color: var(--color-text-dim);
  margin-bottom: 0;
}

.footer-links {
  display: flex;
  gap: var(--spacing-5);
  list-style: none;
}

.footer-links a {
  font-size: 0.85rem;
  color: var(--color-text-dim);
}

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

/* --- Page Title (sub pages) --- */
.page-title {
  text-align: center;
  padding: var(--spacing-12) 0 var(--spacing-4);
}

.page-title h1 {
  margin-bottom: var(--spacing-3);
}

.page-title p {
  max-width: 500px;
  margin: 0 auto;
}

/* --- Not Found / Error --- */
.error-state {
  text-align: center;
  padding: var(--spacing-12);
  color: var(--color-text-dim);
}

.error-state h2 {
  font-size: 1.25rem;
  margin-bottom: var(--spacing-2);
  color: var(--color-text-muted);
}

/* --- Responsive --- */
@media (max-width: 640px) {
  .container {
    padding: 0 var(--spacing-4);
  }

  .site-header .container {
    flex-direction: column;
    gap: var(--spacing-3);
  }

  .nav-links {
    gap: var(--spacing-4);
  }

  .hero-actions {
    flex-direction: column;
  }

  .hero-actions .btn {
    width: 100%;
    justify-content: center;
  }

  .download-options {
    flex-direction: column;
  }

  .site-footer .container {
    flex-direction: column;
    text-align: center;
  }
}