/* =====================================================
   DESIGN TOKENS & CSS CUSTOM PROPERTIES
   ===================================================== */

:root {
  /* Colors - Light Mode */
  --color-bg-primary: #fafafa;
  --color-bg-secondary: #ffffff;
  --color-text-primary: #1a1a1a;
  --color-text-secondary: #5c5c5c;
  --color-border: #e5e5e5;
  --color-accent: #2563eb;
  --color-accent-hover: #1d4ed8;
  --color-success: #16a34a;
  --color-error: #dc2626;

  /* Typography */
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    sans-serif;
  --font-mono: "JetBrains Mono", "SF Mono", "Fira Code", monospace;

  /* Font Sizes */
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 2rem;
  --text-4xl: 3rem;

  /* Font Weights */
  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;

  /* Spacing Scale (8px base) */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 1rem;
  --space-4: 1.5rem;
  --space-5: 2rem;
  --space-6: 3rem;
  --space-7: 4rem;
  --space-8: 6rem;

  /* Layout */
  --container-max: 1200px;
  --content-max: 800px;
  --nav-height: 64px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;

  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
}

/* Dark Mode */
[data-theme="dark"] {
  --color-bg-primary: #0f1419;
  --color-bg-secondary: #1a1f26;
  --color-text-primary: #e7e9ea;
  --color-text-secondary: #8b98a5;
  --color-border: #2f3336;
  --color-accent: #3b82f6;
  --color-accent-hover: #60a5fa;
  --color-success: #22c55e;
  --color-error: #ef4444;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.4);
}

/* =====================================================
   RESET & BASE STYLES
   ===================================================== */

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  font-weight: var(--font-normal);
  line-height: 1.6;
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  transition: background-color var(--transition-base),
    color var(--transition-base);
  min-height: 100vh;
}

#app {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

main {
  flex: 1;
  padding-top: var(--nav-height);
}

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

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

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

a:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

ul,
ol {
  list-style: none;
}

button {
  font-family: inherit;
  font-size: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

button:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* =====================================================
   TYPOGRAPHY
   ===================================================== */

h1,
h2,
h3,
h4,
h5,
h6 {
  color: var(--color-text-primary);
  font-weight: var(--font-bold);
  line-height: 1.2;
  margin-bottom: var(--space-3);
}

h1 {
  font-size: var(--text-4xl);
  letter-spacing: -0.02em;
}

h2 {
  font-size: var(--text-3xl);
  font-weight: var(--font-semibold);
  letter-spacing: -0.01em;
}

h3 {
  font-size: var(--text-2xl);
  font-weight: var(--font-semibold);
}

h4 {
  font-size: var(--text-xl);
  font-weight: var(--font-semibold);
}

p {
  margin-bottom: var(--space-3);
  color: var(--color-text-secondary);
}

code {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  background-color: var(--color-bg-secondary);
  padding: var(--space-1) var(--space-2);
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
}

/* =====================================================
   LAYOUT UTILITIES
   ===================================================== */

.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-4);
}

.content {
  max-width: var(--content-max);
}

.section {
  padding: var(--space-8) 0;
}

.section-header {
  margin-bottom: var(--space-6);
}

/* =====================================================
   NAVBAR
   ===================================================== */

.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background-color: var(--color-bg-secondary);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
  transition: background-color var(--transition-base),
    border-color var(--transition-base);
}

.navbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-4);
}

.navbar-logo {
  font-size: var(--text-lg);
  font-weight: var(--font-bold);
  color: var(--color-text-primary);
  text-decoration: none;
}

.navbar-logo:hover {
  color: var(--color-accent);
}

.navbar-nav {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.navbar-link {
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  color: var(--color-text-secondary);
  text-decoration: none;
  padding: var(--space-2) var(--space-2);
  transition: color var(--transition-fast);
}

.navbar-link:hover,
.navbar-link.active {
  color: var(--color-text-primary);
}

.navbar-actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

/* Mobile Menu Toggle */
.navbar-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 40px;
  height: 40px;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-2);
}

.navbar-toggle span {
  display: block;
  width: 20px;
  height: 2px;
  background-color: var(--color-text-primary);
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.navbar-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.navbar-toggle.active span:nth-child(2) {
  opacity: 0;
}

.navbar-toggle.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* =====================================================
   BUTTONS
   ===================================================== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  cursor: pointer;
  text-decoration: none;
  border: none;
}

.btn-primary {
  background-color: var(--color-accent);
  color: white;
}

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

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

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

.btn-ghost {
  background-color: transparent;
  color: var(--color-text-secondary);
  padding: var(--space-2);
}

.btn-ghost:hover {
  color: var(--color-text-primary);
  background-color: var(--color-bg-secondary);
}

.btn-sm {
  padding: var(--space-1) var(--space-3);
  font-size: var(--text-xs);
}

/* =====================================================
   THEME TOGGLE
   ===================================================== */

.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background: transparent;
  border: 1px solid var(--color-border);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.theme-toggle:hover {
  background-color: var(--color-bg-primary);
  border-color: var(--color-text-secondary);
}

.theme-toggle svg {
  width: 20px;
  height: 20px;
  color: var(--color-text-primary);
}

.theme-toggle .sun-icon {
  display: none;
}

.theme-toggle .moon-icon {
  display: block;
}

[data-theme="dark"] .theme-toggle .sun-icon {
  display: block;
}

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

/* =====================================================
   CARDS
   ===================================================== */

.card {
  background-color: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-4);
  transition: all var(--transition-fast);
}

.card:hover {
  box-shadow: var(--shadow-md);
}

.card-header {
  margin-bottom: var(--space-3);
}

.card-title {
  font-size: var(--text-xl);
  font-weight: var(--font-semibold);
  margin-bottom: var(--space-2);
  color: var(--color-text-primary);
}

.card-subtitle {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
}

.card-content {
  margin-bottom: var(--space-3);
}

.card-footer {
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
}

/* =====================================================
   BADGES
   ===================================================== */

.badge {
  display: inline-flex;
  align-items: center;
  padding: var(--space-1) var(--space-2);
  font-size: var(--text-xs);
  font-weight: var(--font-medium);
  background-color: var(--color-bg-primary);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
}

.badge-accent {
  background-color: rgba(37, 99, 235, 0.1);
  color: var(--color-accent);
  border-color: transparent;
}

/* =====================================================
   SKILL CATEGORIES
   ===================================================== */

.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-4);
}

.skill-category {
  background-color: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-4);
}

.skill-category-title {
  font-size: var(--text-lg);
  font-weight: var(--font-semibold);
  margin-bottom: var(--space-3);
  color: var(--color-text-primary);
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.skill-category-title svg {
  width: 20px;
  height: 20px;
  color: var(--color-accent);
}

.skill-list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

/* =====================================================
   TIMELINE
   ===================================================== */

.timeline {
  position: relative;
  padding-left: var(--space-5);
}

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

.timeline-item {
  position: relative;
  padding-bottom: var(--space-6);
}

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

.timeline-item::before {
  content: "";
  position: absolute;
  left: calc(-1 * var(--space-5) - 4px);
  top: 6px;
  width: 10px;
  height: 10px;
  background-color: var(--color-accent);
  border-radius: 50%;
}

.timeline-header {
  margin-bottom: var(--space-2);
}

.timeline-title {
  font-size: var(--text-xl);
  font-weight: var(--font-semibold);
  margin-bottom: var(--space-1);
  color: var(--color-text-primary);
}

.timeline-subtitle {
  font-size: var(--text-base);
  color: var(--color-accent);
  font-weight: var(--font-medium);
}

.timeline-date {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-3);
}

.timeline-content ul {
  list-style: disc;
  padding-left: var(--space-4);
}

.timeline-content li {
  color: var(--color-text-secondary);
  margin-bottom: var(--space-2);
  line-height: 1.6;
}

/* =====================================================
   PROJECT CARDS
   ===================================================== */

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
  gap: var(--space-4);
}

.project-card {
  background-color: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  transition: all var(--transition-fast);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.project-thumbnail {
  width: 100%;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  margin-bottom: var(--space-4);
  background-color: var(--color-bg-primary);
}

.project-thumbnail img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-base);
}

.project-card:hover .project-thumbnail img {
  transform: scale(1.05);
}

.project-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--color-text-secondary);
}

.project-title {
  font-size: var(--text-xl);
  font-weight: var(--font-semibold);
  margin-bottom: var(--space-2);
  color: var(--color-text-primary);
}

.project-problem {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-3);
  line-height: 1.6;
}

.project-section {
  margin-bottom: var(--space-3);
}

.project-section-title {
  font-size: var(--text-sm);
  font-weight: var(--font-semibold);
  color: var(--color-text-primary);
  margin-bottom: var(--space-2);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.project-tech {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
}

.project-links {
  display: flex;
  gap: var(--space-3);
  margin-top: auto;
  padding-top: var(--space-3);
  border-top: 1px solid var(--color-border);
}

.project-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  color: var(--color-accent);
}

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

.project-link svg {
  width: 16px;
  height: 16px;
}

/* =====================================================
   FORMS
   ===================================================== */

.form-group {
  margin-bottom: var(--space-4);
}

.form-label {
  display: block;
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  color: var(--color-text-primary);
  margin-bottom: var(--space-2);
}

.form-input,
.form-textarea {
  width: 100%;
  padding: var(--space-3);
  font-size: var(--text-base);
  font-family: var(--font-sans);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  transition: border-color var(--transition-fast),
    box-shadow var(--transition-fast);
}

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

.form-input::placeholder,
.form-textarea::placeholder {
  color: var(--color-text-secondary);
  opacity: 0.6;
}

.form-textarea {
  min-height: 150px;
  resize: vertical;
}

.form-error {
  font-size: var(--text-sm);
  color: var(--color-error);
  margin-top: var(--space-1);
}

.form-success {
  font-size: var(--text-sm);
  color: var(--color-success);
  margin-top: var(--space-1);
}

/* =====================================================
   FOOTER
   ===================================================== */

.footer {
  background-color: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  padding: var(--space-6) 0;
  margin-top: auto;
}

.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-4);
  text-align: center;
}

.footer-links {
  display: flex;
  gap: var(--space-4);
}

.footer-link {
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
}

.footer-link:hover {
  color: var(--color-text-primary);
}

.footer-link svg {
  width: 24px;
  height: 24px;
}

.footer-text {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  margin-bottom: 0;
}

/* =====================================================
   HOME PAGE
   ===================================================== */

.hero {
  min-height: calc(100vh - var(--nav-height));
  display: flex;
  align-items: center;
  padding: var(--space-8) 0;
}

.hero-container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  align-items: center;
  gap: var(--space-6);
}

.hero-content {
  max-width: 600px;
}

.hero-image {
  position: relative;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  aspect-ratio: 1 / 1;
}

.hero-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.hero-subtitle {
  font-size: var(--text-lg);
  font-weight: var(--font-medium);
  color: var(--color-accent);
  margin-bottom: var(--space-3);
}

.hero-title {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: var(--font-bold);
  line-height: 1.2;
  margin-bottom: var(--space-4);
  color: var(--color-text-primary);
}

.hero-description {
  font-size: var(--text-lg);
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-6);
  max-width: 600px;
}

.hero-actions {
  display: flex;
  gap: var(--space-3);
  flex-wrap: wrap;
}

/* =====================================================
   CONTACT PAGE
   ===================================================== */

.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-6);
}

.contact-info h3 {
  margin-bottom: var(--space-4);
}

.contact-links {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.contact-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-base);
  color: var(--color-text-secondary);
}

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

.contact-link svg {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
}

/* =====================================================
   RESPONSIVE STYLES
   ===================================================== */

@media (max-width: 1024px) {
  :root {
    --text-4xl: 2.5rem;
    --text-3xl: 1.75rem;
  }

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

@media (max-width: 768px) {
  :root {
    --nav-height: 56px;
  }

  .navbar-nav {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background-color: var(--color-bg-secondary);
    border-bottom: 1px solid var(--color-border);
    flex-direction: column;
    padding: var(--space-4);
    gap: var(--space-2);
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: transform var(--transition-base), opacity var(--transition-base);
  }

  .navbar-nav.active {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }

  .navbar-link {
    width: 100%;
    padding: var(--space-3);
    text-align: center;
  }

  .navbar-toggle {
    display: flex;
  }

  .navbar-actions {
    gap: var(--space-2);
  }

  .hero {
    min-height: auto;
    padding: var(--space-6) 0;
  }

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

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

  .hero-container {
    grid-template-columns: 1fr;
    gap: var(--space-4);
    text-align: center;
  }

  .hero-content {
    max-width: 100%;
    order: 2;
  }

  .hero-image {
    order: 1;
    max-width: 300px;
    margin: 0 auto;
  }

  .hero-description {
    margin: 0 auto var(--space-6);
  }

  .section {
    padding: var(--space-6) 0;
  }

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

  .timeline {
    padding-left: var(--space-4);
  }

  .timeline-item::before {
    left: calc(-1 * var(--space-4) - 4px);
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--space-3);
  }

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

  h2 {
    font-size: var(--text-2xl);
  }
}

/* =====================================================
   ACCESSIBILITY
   ===================================================== */

.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;
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  html {
    scroll-behavior: auto;
  }
}

/* Focus visible for keyboard navigation */
:focus:not(:focus-visible) {
  outline: none;
}

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