/* CSS Variables */
:root {
  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
  --color-text: #1f2937;
  --color-text-muted: #6b7280;
  --color-text-light: #9ca3af;
  --color-bg: #ffffff;
  --color-bg-alt: #f9fafb;
  --color-border: #e5e7eb;
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --max-width: 800px;
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --spacing-2xl: 5rem;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color 0.2s ease;
}

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

ul {
  list-style: none;
}

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

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

/* Section Title */
.section-title {
  font-size: 1.75rem;
  font-weight: 600;
  margin-bottom: var(--spacing-xl);
  text-align: center;
  color: var(--color-text);
}

/* Hero Section */
#hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}

.hero-content {
  text-align: center;
  animation: fadeInUp 0.8s ease-out;
}

.hero-name {
  font-size: clamp(2.5rem, 8vw, 4rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: var(--spacing-xs);
  color: var(--color-text);
}

.hero-tagline {
  font-size: clamp(1rem, 3vw, 1.25rem);
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-lg);
  font-weight: 400;
}

.hero-links {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
  margin-bottom: var(--spacing-2xl);
}

.hero-links a {
  color: var(--color-text-muted);
  transition: color 0.2s ease, transform 0.2s ease;
}

.hero-links a:hover {
  color: var(--color-primary);
  transform: translateY(-2px);
}

.hero-scroll {
  position: absolute;
  bottom: var(--spacing-lg);
  left: 50%;
  transform: translateX(-50%);
  color: var(--color-text-light);
  animation: bounce 2s infinite;
}

.hero-scroll:hover {
  color: var(--color-primary);
}

/* About Section */
#about {
  padding: var(--spacing-xl) 0 var(--spacing-2xl);
}

.about-text {
  font-size: 1.125rem;
  line-height: 1.8;
  color: var(--color-text-muted);
  text-align: center;
  max-width: 650px;
  margin: 0 auto;
}

/* Experience Section (formerly Timeline) */
#experience {
  padding: var(--spacing-2xl) 0;
}

/* Timeline Section */
#timeline {
  padding: var(--spacing-2xl) 0;
}

.timeline {
  position: relative;
  padding-left: var(--spacing-lg);
}

.timeline::before {
  content: '';
  position: absolute;
  left: 6px;
  top: 0;
  bottom: 0;
  width: 2px;
  background-color: var(--color-border);
}

.timeline-item {
  position: relative;
  padding-bottom: var(--spacing-xl);
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.timeline-item.visible {
  opacity: 1;
  transform: translateY(0);
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-dot {
  position: absolute;
  left: calc(-1 * var(--spacing-lg) + 2px);
  top: 4px;
  width: 10px;
  height: 10px;
  background-color: var(--color-primary);
  border-radius: 50%;
  border: 2px solid var(--color-bg);
  box-shadow: 0 0 0 2px var(--color-primary);
}

.timeline-project .timeline-dot {
  background-color: var(--color-bg);
}

.timeline-content {
  background-color: var(--color-bg);
  padding: var(--spacing-md);
  border-radius: 8px;
  border: 1px solid var(--color-border);
  transition: box-shadow 0.2s ease;
}

.timeline-content:hover {
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.timeline-date {
  font-size: 0.875rem;
  color: var(--color-text-light);
  font-weight: 500;
}

.timeline-title {
  font-size: 1.125rem;
  font-weight: 600;
  margin: var(--spacing-xs) 0;
  color: var(--color-text);
}

.timeline-company {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-sm);
}

.timeline-details {
  padding-left: var(--spacing-md);
}

.timeline-details li {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-xs);
  position: relative;
  list-style: disc;
}

.timeline-details li:last-child {
  margin-bottom: 0;
}

.timeline-links {
  margin-top: var(--spacing-sm);
}

.timeline-links a {
  font-size: 0.875rem;
  font-weight: 500;
}

/* Projects Section */
#projects {
  padding: var(--spacing-2xl) 0;
  background-color: var(--color-bg-alt);
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--spacing-lg);
}

.project-card {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: var(--spacing-md);
  transition: box-shadow 0.2s ease, transform 0.2s ease;
}

.project-card:hover {
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
  transform: translateY(-2px);
}

.project-title {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--spacing-xs);
}

.project-description {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-sm);
  line-height: 1.5;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.375rem;
  margin-bottom: var(--spacing-sm);
}

.project-tag {
  display: inline-block;
  padding: 0.25rem 0.625rem;
  background-color: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: 9999px;
  font-size: 0.75rem;
  color: var(--color-text-muted);
  font-weight: 500;
}

.project-links {
  display: flex;
  gap: var(--spacing-xs);
}

.project-links a {
  display: inline-block;
  padding: 0.375rem 0.75rem;
  font-size: 0.875rem;
  font-weight: 500;
  border-radius: 6px;
  border: 1px solid var(--color-border);
  background-color: var(--color-bg);
  transition: border-color 0.2s ease, background-color 0.2s ease;
}

.project-links a:hover {
  border-color: var(--color-primary);
  background-color: rgba(37, 99, 235, 0.05);
}

/* Skills Section */
#skills {
  padding: var(--spacing-2xl) 0;
  background-color: var(--color-bg);
}

.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--spacing-lg);
}

.skills-category h3 {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--spacing-sm);
}

.skills-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-xs);
}

.skill-tag {
  display: inline-block;
  padding: 0.375rem 0.75rem;
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 9999px;
  font-size: 0.875rem;
  color: var(--color-text);
  transition: border-color 0.2s ease, background-color 0.2s ease;
}

.skill-tag:hover {
  border-color: var(--color-primary);
  background-color: rgba(37, 99, 235, 0.05);
}

/* Contact Section */
#contact {
  padding: var(--spacing-2xl) 0;
}

.contact-form {
  max-width: 500px;
  margin: 0 auto var(--spacing-xl);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-sm);
}

.form-group {
  margin-bottom: var(--spacing-sm);
}

.form-group label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: var(--spacing-xs);
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 0.75rem 1rem;
  font-family: var(--font-family);
  font-size: 1rem;
  color: var(--color-text);
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 6px;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-group textarea {
  resize: vertical;
  min-height: 120px;
}

.btn-submit {
  display: block;
  width: 100%;
  padding: 0.875rem 1.5rem;
  font-family: var(--font-family);
  font-size: 1rem;
  font-weight: 500;
  color: #ffffff;
  background-color: var(--color-primary);
  border: none;
  border-radius: 6px;
  cursor: pointer;
  transition: background-color 0.2s ease, transform 0.2s ease;
}

.btn-submit:hover {
  background-color: var(--color-primary-hover);
}

.btn-submit:active {
  transform: scale(0.98);
}

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

.contact-links a {
  color: var(--color-text-muted);
  transition: color 0.2s ease;
}

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

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

footer p {
  font-size: 0.875rem;
  color: var(--color-text-light);
}

/* Animations */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes bounce {
  0%, 20%, 50%, 80%, 100% {
    transform: translateX(-50%) translateY(0);
  }
  40% {
    transform: translateX(-50%) translateY(-10px);
  }
  60% {
    transform: translateX(-50%) translateY(-5px);
  }
}

/* Responsive */
@media (max-width: 640px) {
  .form-row {
    grid-template-columns: 1fr;
  }

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

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

  .timeline {
    padding-left: var(--spacing-md);
  }

  .timeline-dot {
    left: calc(-1 * var(--spacing-md) + 2px);
  }

  .section-title {
    font-size: 1.5rem;
  }

  .about-text {
    font-size: 1rem;
  }
}

@media (max-width: 480px) {
  .hero-name {
    font-size: 2rem;
  }

  .hero-tagline {
    font-size: 1rem;
  }

  .container {
    padding: 0 var(--spacing-sm);
  }
}