/* Layout System */
/* Mobile-first responsive layout using CSS Grid and Flexbox */

/* Main Grid Container */
html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family-primary), var(--font-family-chinese);
  background-color: #000;
  color: var(--color-text-primary);
  overflow-x: hidden;
  /* Fix mobile viewport height issues */
  min-height: 100vh;
  min-height: 100svh; /* Small viewport height for mobile */
  display: grid;
  grid-template-rows: auto minmax(0, 1fr) auto; /* Prevent main from overflowing */
  grid-template-areas: 
    "header"
    "main"
    "footer";
  /* Control overflow behavior */
  overflow-y: auto;
  height: 100vh; /* Explicit height to prevent expansion */
  height: 100svh; /* Modern mobile viewport */
}

/* Background Container */
.background {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
  
  /* Ultra-fast placeholder for instant visual feedback */
  background-image: url('../assets/bg-placeholder.jpg');
  background-color: rgba(0, 0, 0, 0.85); /* Fallback color */
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  background-attachment: scroll; /* Better performance than fixed */
  
  /* Smooth transition when optimized image loads */
  transition: background-image 0.5s ease-in-out;
}

/* Progressive responsive background loading */
.background.loaded {
  background-image: url('../assets/bg-mobile.webp');
}

/* Mobile devices */
@media (max-width: 767px) {
  .background.loaded {
    background-image: url('../assets/bg-mobile.webp');
  }
  
  /* Fallback for browsers without WebP support */
  .no-webp .background.loaded {
    background-image: url('../assets/bg-mobile.jpg');
  }
}

/* Tablets */
@media (min-width: 768px) and (max-width: 1199px) {
  .background.loaded {
    background-image: url('../assets/bg-tablet.webp');
  }
  
  .no-webp .background.loaded {
    background-image: url('../assets/bg-tablet.jpg');
  }
}

/* Desktop */
@media (min-width: 1200px) {
  .background.loaded {
    background-image: url('../assets/bg-desktop.webp');
  }
  
  .no-webp .background.loaded {
    background-image: url('../assets/bg-desktop.jpg');
  }
}

/* High-resolution displays */
@media (min-width: 1200px) and (-webkit-min-device-pixel-ratio: 2) {
  .background.loaded {
    background-image: url('../assets/bg-hd.webp');
  }
  
  .no-webp .background.loaded {
    background-image: url('../assets/bg-hd.jpg');
  }
}

.background::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: var(--color-background-overlay);
  backdrop-filter: blur(1px);
}

/* Header */
.header {
  grid-area: header;
  padding: var(--space-2) var(--space-4) 0;
  z-index: 10;
  /* Minimize header height on mobile */
  flex-shrink: 0;
}

/* Main Content Area */
.main {
  grid-area: main;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: var(--space-4) var(--space-4);
  min-height: 0;
  text-align: center;
  position: relative;
  z-index: 10;
  /* Ensure content fits in viewport */
  box-sizing: border-box;
}

/* Footer */
.footer {
  grid-area: footer;
  padding: 0 var(--space-4) var(--space-2);
  z-index: 10;
  margin-top: auto;
  /* Minimize footer height on mobile */
  flex-shrink: 0;
}

/* Content Container for max-width control */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-4);
}

/* Responsive Breakpoints */

/* Small devices (landscape phones, 576px and up) */
@media (min-width: 576px) {
  .main {
    padding: var(--space-8) var(--space-6);
  }
  
  .container {
    padding: 0 var(--space-6);
  }
}

/* Medium devices (tablets, 768px and up) */
@media (min-width: 768px) {
  body {
    grid-template-rows: auto 1fr auto;
  }
  
  .main {
    padding: var(--space-16) var(--space-8);
  }
  
  .header {
    padding: var(--space-6) var(--space-8) 0;
  }
  
  .footer {
    padding: 0 var(--space-8) var(--space-6);
  }
  
  .container {
    padding: 0 var(--space-8);
  }
}

/* Large devices (desktops, 992px and up) */
@media (min-width: 992px) {
  .main {
    padding: var(--space-20) var(--space-10);
  }
  
  .header {
    padding: var(--space-8) var(--space-10) 0;
  }
  
  .footer {
    padding: 0 var(--space-10) var(--space-8);
  }
  
  .container {
    padding: 0 var(--space-10);
  }
}

/* Extra large devices (large desktops, 1200px and up) */
@media (min-width: 1200px) {
  .main {
    padding: var(--space-24) var(--space-12);
  }
}

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

.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;
}

/* Focus management */
.skip-link {
  position: absolute;
  top: -40px;
  left: 6px;
  background: var(--color-accent);
  color: white;
  padding: 8px;
  text-decoration: none;
  border-radius: var(--radius-md);
  z-index: 1000;
}

.skip-link:focus {
  top: 6px;
}

/* Mobile-specific optimizations to prevent scrollbars */
@media (max-width: 575px) {
  /* Fine-tune mobile layout to fit perfectly in viewport */
  .main {
    padding: var(--space-3) var(--space-4);
    justify-content: space-around; /* Better space distribution */
  }
  
  .header {
    padding: var(--space-1) var(--space-4) 0;
  }
  
  .footer {
    padding: 0 var(--space-4) var(--space-1);
  }
  
  /* Ensure avatar doesn't cause overflow */
  .avatar {
    margin-bottom: var(--space-4);
  }
  
  /* Optimize social links spacing */
  .social-links {
    gap: var(--space-3);
    margin: var(--space-3) 0;
  }
}

/* Mobile landscape optimization */
@media (max-width: 767px) and (orientation: landscape) {
  body {
    min-height: 100vh;
    min-height: 100lvh; /* Large viewport height for landscape */
  }
  
  .main {
    padding: var(--space-2) var(--space-4);
    justify-content: center;
  }
  
  .header {
    padding: var(--space-1) var(--space-4) 0;
  }
  
  .footer {
    padding: 0 var(--space-4) var(--space-1);
  }
}

/* Reduced motion preferences */
@media (prefers-reduced-motion: reduce) {
  .background {
    background-attachment: scroll;
  }
}