/* ==========================================================================
   BioStack Design System
   A restrained, functional, accessible interface built for clarity and content hierarchy.
   Supports Light & Dark Modes via system preference and manual toggle.
   ========================================================================== */

:root {
  /* Default Light Palette (WCAG 2.2 AA Compliant) */
  --color-bg: #f8fafc;
  --color-surface: #ffffff;
  --color-surface-hover: #f1f5f9;
  --color-border: #e2e8f0;
  --color-border-hover: #94a3b8;
  
  --color-text-primary: #0f172a;
  --color-text-secondary: #334155;
  --color-text-muted: #64748b;
  
  --color-brand: #0f172a;
  --color-accent: #0284c7;
  --color-accent-hover: #0369a1;
  --color-focus: #0284c7;
  
  /* Typography Scale */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-size-title: 1.5rem;    /* 24px - Page Heading */
  --font-size-body: 1rem;       /* 16px - Primary Link Title */
  --font-size-sub: 0.875rem;    /* 14px - Body Bio & Subtext */
  
  /* Spacing Scale */
  --space-1: 0.25rem;  /* 4px */
  --space-2: 0.5rem;   /* 8px */
  --space-3: 0.75rem;  /* 12px */
  --space-4: 1rem;     /* 16px */
  --space-6: 1.5rem;   /* 24px */
  --space-8: 2rem;     /* 32px */
  
  /* Geometry & Shadows */
  --radius-avatar: 50%;
  --radius-surface: 6px;
  --shadow-sm: 0 1px 3px 0 rgba(15, 23, 42, 0.06), 0 1px 2px -1px rgba(15, 23, 42, 0.04);
}

/* System Dark Mode Preference */
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #0f172a;
    --color-surface: #1e293b;
    --color-surface-hover: #334155;
    --color-border: #334155;
    --color-border-hover: #64748b;
    
    --color-text-primary: #f8fafc;
    --color-text-secondary: #cbd5e1;
    --color-text-muted: #94a3b8;
    
    --color-brand: #f8fafc;
    --color-accent: #38bdf8;
    --color-accent-hover: #7dd3fc;
    --color-focus: #38bdf8;
    --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.3);
  }
}

/* Manual Theme Overrides */
[data-theme="light"] {
  --color-bg: #f8fafc;
  --color-surface: #ffffff;
  --color-surface-hover: #f1f5f9;
  --color-border: #e2e8f0;
  --color-border-hover: #94a3b8;
  
  --color-text-primary: #0f172a;
  --color-text-secondary: #334155;
  --color-text-muted: #64748b;
  
  --color-brand: #0f172a;
  --color-accent: #0284c7;
  --color-accent-hover: #0369a1;
  --color-focus: #0284c7;
  --shadow-sm: 0 1px 3px 0 rgba(15, 23, 42, 0.06);
}

[data-theme="dark"] {
  --color-bg: #0f172a;
  --color-surface: #1e293b;
  --color-surface-hover: #334155;
  --color-border: #334155;
  --color-border-hover: #64748b;
  
  --color-text-primary: #f8fafc;
  --color-text-secondary: #cbd5e1;
  --color-text-muted: #94a3b8;
  
  --color-brand: #f8fafc;
  --color-accent: #38bdf8;
  --color-accent-hover: #7dd3fc;
  --color-focus: #38bdf8;
  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.3);
}

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

html {
  font-family: var(--font-family);
  background-color: var(--color-bg);
  color: var(--color-text-primary);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  padding: var(--space-8) var(--space-4);
}

.page-container {
  width: 100%;
  max-width: 560px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
}

/* Header Section */
.profile-header {
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  margin-bottom: var(--space-6);
}

.profile-avatar {
  width: 88px;
  height: 88px;
  border-radius: var(--radius-avatar);
  object-fit: cover;
  border: 1px solid var(--color-border);
  margin-bottom: var(--space-4);
  background-color: var(--color-surface);
}

.profile-title {
  font-size: var(--font-size-title);
  font-weight: 700;
  color: var(--color-text-primary);
  letter-spacing: -0.02em;
  margin-bottom: var(--space-1);
}

.profile-handle {
  font-size: var(--font-size-sub);
  color: var(--color-accent);
  font-weight: 600;
  margin-bottom: var(--space-3);
}

.profile-bio {
  font-size: var(--font-size-sub);
  color: var(--color-text-secondary);
  max-width: 460px;
  line-height: 1.55;
  margin-bottom: var(--space-6);
}

/* Social Navigation Bar & Controls */
.social-nav {
  display: flex;
  gap: var(--space-3);
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
}

.social-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  min-height: 40px;
  padding: var(--space-2) var(--space-4);
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-surface);
  color: var(--color-text-primary);
  text-decoration: none;
  font-size: var(--font-size-sub);
  font-weight: 500;
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}

.social-link:hover {
  background-color: var(--color-surface-hover);
  border-color: var(--color-border-hover);
  color: var(--color-accent-hover);
}

.social-link:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}

.social-link.copied {
  background-color: #f0fdf4;
  border-color: #86efac;
  color: #166534;
}

[data-theme="dark"] .social-link.copied,
@media (prefers-color-scheme: dark) {
  .social-link.copied {
    background-color: #064e3b;
    border-color: #059669;
    color: #a7f3d0;
  }
}

.nav-icon {
  flex-shrink: 0;
}

/* Theme Icon Visibility */
.theme-icon-sun {
  display: none;
}
.theme-icon-moon {
  display: block;
}

[data-theme="dark"] .theme-icon-sun {
  display: block;
}
[data-theme="dark"] .theme-icon-moon {
  display: none;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .theme-icon-sun {
    display: block;
  }
  :root:not([data-theme="light"]) .theme-icon-moon {
    display: none;
  }
}

/* Main Link Stack */
.link-stack {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.link-item {
  display: flex;
  align-items: center;
  width: 100%;
  min-height: 60px;
  padding: var(--space-3) var(--space-4);
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-surface);
  text-decoration: none;
  color: var(--color-text-primary);
  box-shadow: var(--shadow-sm);
  transition: border-color 0.15s ease, background-color 0.15s ease;
}

.link-item:hover {
  border-color: var(--color-accent);
  background-color: var(--color-surface-hover);
}

.link-item:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}

/* Primary Action Callout (Dominant Link) */
.link-item.primary-action {
  border-left: 4px solid var(--color-accent);
}

.link-icon-container {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  margin-right: var(--space-3);
  color: var(--color-text-secondary);
  flex-shrink: 0;
}

.link-item:hover .link-icon-container {
  color: var(--color-accent);
}

.link-text {
  display: flex;
  flex-direction: column;
  flex-grow: 1;
  min-width: 0;
}

.link-title {
  font-size: var(--font-size-body);
  font-weight: 600;
  line-height: 1.35;
  color: var(--color-text-primary);
}

.link-description {
  font-size: var(--font-size-sub);
  color: var(--color-text-muted);
  margin-top: 2px;
  line-height: 1.4;
}

.chevron-icon {
  margin-left: var(--space-3);
  flex-shrink: 0;
  color: var(--color-text-muted);
  transition: color 0.15s ease, transform 0.15s ease;
}

.link-item:hover .chevron-icon {
  color: var(--color-accent);
  transform: translateX(2px);
}

/* Site Footer */
.site-footer {
  margin-top: var(--space-8);
  margin-bottom: var(--space-4);
  text-align: center;
}

.site-footer p {
  font-size: var(--font-size-sub);
  color: var(--color-text-muted);
}

/* Accessibility: Reduced Motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
  
  .chevron-icon {
    transform: none !important;
  }
}

/* Responsive adjustments */
@media (max-width: 480px) {
  body {
    padding: var(--space-6) var(--space-3);
  }
  
  .link-item {
    padding: var(--space-3);
  }
}