/* ========================================
   CSS Variables - Easy Dark Mode Toggle
   ======================================== */
:root {
  /* Colors */
  --color-bg: #ffffff;
  --color-bg-alt: #f8f9fa;
  --color-text: #2c3e50;
  --color-text-muted: #6c757d;
  --color-accent: #2563eb;
  --color-accent-hover: #1d4ed8;
  --color-card-bg: #ffffff;
  --color-card-border: #e5e7eb;
  --color-footer-bg: #f8f9fa;

  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 2rem;
  --spacing-lg: 4rem;
  --spacing-xl: 6rem;

  /* Typography */
  --font-body: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI',
               Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-heading: var(--font-body);
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.5rem;
  --font-size-2xl: 2rem;
  --font-size-3xl: 2.5rem;
  --line-height-normal: 1.6;
  --line-height-heading: 1.2;

  /* Layout */
  --container-max-width: 1200px;
  --border-radius: 0.5rem;
  --transition-speed: 0.2s;
}

/* Future: Dark mode override
[data-theme="dark"] {
  --color-bg: #1a1a1a;
  --color-bg-alt: #2d2d2d;
  --color-text: #e5e5e5;
  --color-text-muted: #a0a0a0;
  --color-card-bg: #2d2d2d;
  --color-card-border: #404040;
  --color-footer-bg: #2d2d2d;
}
*/

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ========================================
   Typography
   ======================================== */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  line-height: var(--line-height-heading);
  font-weight: 700;
  margin-bottom: var(--spacing-sm);
}

h1 {
  font-size: var(--font-size-3xl);
}

h2 {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--spacing-md);
}

p {
  margin-bottom: var(--spacing-sm);
}

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

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

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

main {
  min-height: 100vh;
}

section {
  padding: var(--spacing-lg) 0;
}

/* ========================================
   Hero Section
   ======================================== */
.hero {
  background: linear-gradient(135deg, var(--color-bg-alt) 0%, var(--color-bg) 100%);
  text-align: center;
  padding: var(--spacing-xl) 0;
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3.5rem);
  margin-bottom: var(--spacing-sm);
  color: var(--color-text);
}

.tagline {
  font-size: var(--font-size-lg);
  color: var(--color-text-muted);
  max-width: 600px;
  margin: 0 auto;
}

/* ========================================
   About Section
   ======================================== */
.about {
  background-color: var(--color-bg);
}

.about p {
  max-width: 700px;
  margin-left: auto;
  margin-right: auto;
  font-size: var(--font-size-lg);
  color: var(--color-text);
}

/* ========================================
   Projects Section
   ======================================== */
.projects {
  background-color: var(--color-bg-alt);
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--spacing-md);
  margin-top: var(--spacing-md);
}

.project-card {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-card-border);
  border-radius: var(--border-radius);
  padding: var(--spacing-md);
  transition: transform var(--transition-speed) ease,
              box-shadow var(--transition-speed) ease;
}

.project-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.1);
}

.project-card h3 {
  font-size: var(--font-size-xl);
  margin-bottom: var(--spacing-sm);
  color: var(--color-text);
}

.project-card p {
  color: var(--color-text);
  margin-bottom: var(--spacing-md);
}

.project-link {
  display: inline-block;
  color: var(--color-accent);
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
}

.project-link:hover {
  color: var(--color-accent-hover);
}

.tech-stack {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-xs);
  margin-top: var(--spacing-sm);
}

.tech-tag {
  background-color: var(--color-bg-alt);
  color: var(--color-text-muted);
  padding: 0.25rem 0.75rem;
  border-radius: calc(var(--border-radius) / 2);
  font-size: 0.875rem;
  border: 1px solid var(--color-card-border);
  /* Future: Can add data-tag attribute for filtering */
}

/* ========================================
   Contact Section
   ======================================== */
.contact {
  background-color: var(--color-bg);
  text-align: center;
}

.contact p {
  font-size: var(--font-size-lg);
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-md);
}

.contact-links {
  display: flex;
  justify-content: center;
  gap: var(--spacing-md);
  flex-wrap: wrap;
}

.contact-link {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-xs);
  padding: var(--spacing-md);
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-card-border);
  border-radius: var(--border-radius);
  min-width: 120px;
  transition: transform var(--transition-speed) ease,
              box-shadow var(--transition-speed) ease;
}

.contact-link:hover {
  transform: translateY(-4px);
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

.contact-icon {
  font-size: 2rem;
}

/* ========================================
   Footer
   ======================================== */
.footer {
  background-color: var(--color-footer-bg);
  padding: var(--spacing-md) 0;
  text-align: center;
  border-top: 1px solid var(--color-card-border);
}

.footer p {
  color: var(--color-text-muted);
  font-size: 0.875rem;
  margin: 0;
}

/* ========================================
   Responsive Design
   ======================================== */
@media (max-width: 768px) {
  :root {
    --spacing-lg: 3rem;
    --spacing-xl: 4rem;
  }

  .projects-grid {
    grid-template-columns: 1fr;
  }

  .contact-links {
    flex-direction: column;
    align-items: center;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--spacing-sm);
  }
}