/* =============================================
   CSS Custom Properties (Theme Variables)
   ============================================= */
:root {
  /* Colors - Light Theme */
  --color-bg: #f8f9fa;
  --color-bg-alt: #ffffff;
  --color-bg-card: #ffffff;
  --color-text: #1a1a2e;
  --color-text-secondary: #4a4a6a;
  --color-text-muted: #6c6c8a;
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-primary-light: #3b82f6;
  --color-primary-bg: rgba(37, 99, 235, 0.08);
  --color-accent: #06b6d4;
  --color-border: #e2e8f0;
  --color-shadow: rgba(0, 0, 0, 0.08);
  --color-shadow-hover: rgba(0, 0, 0, 0.12);
  --color-badge-bg: #eef2ff;
  --color-badge-text: #4338ca;
  --color-hero-gradient: linear-gradient(135deg, #f8f9fa 0%, #e8eeff 100%);
  --color-featured-bg: linear-gradient(135deg, #1e3a5f 0%, #2563eb 100%);
  --color-skill-bar-bg: #e2e8f0;
  --color-skill-bar-fill: var(--color-primary);
  --color-input-bg: #ffffff;
  --color-input-border: #d1d5db;
  --color-footer-bg: #1a1a2e;
  --color-footer-text: #cbd5e1;

  /* Typography */
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'Fira Code', 'Consolas', monospace;

  /* Spacing */
  --section-padding: 5rem 0;
  --container-max: 1100px;
  --container-padding: 1.5rem;

  /* Transitions */
  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s ease;

  /* Border Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;
}

/* Dark Theme */
[data-theme="dark"] {
  --color-bg: #0f172a;
  --color-bg-alt: #1e293b;
  --color-bg-card: #1e293b;
  --color-text: #e2e8f0;
  --color-text-secondary: #94a3b8;
  --color-text-muted: #64748b;
  --color-primary: #3b82f6;
  --color-primary-dark: #2563eb;
  --color-primary-light: #60a5fa;
  --color-primary-bg: rgba(59, 130, 246, 0.12);
  --color-accent: #22d3ee;
  --color-border: #334155;
  --color-shadow: rgba(0, 0, 0, 0.3);
  --color-shadow-hover: rgba(0, 0, 0, 0.4);
  --color-badge-bg: rgba(99, 102, 241, 0.15);
  --color-badge-text: #818cf8;
  --color-hero-gradient: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
  --color-featured-bg: linear-gradient(135deg, #1e3a5f 0%, #1e40af 100%);
  --color-skill-bar-bg: #334155;
  --color-skill-bar-fill: var(--color-primary-light);
  --color-input-bg: #1e293b;
  --color-input-border: #475569;
  --color-footer-bg: #020617;
  --color-footer-text: #64748b;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
}

body {
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
  transition: background-color var(--transition-normal), color var(--transition-normal);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

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

ul {
  list-style: none;
}

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

.section {
  padding: var(--section-padding);
}

.section--alt {
  background-color: var(--color-bg-alt);
}

.section__title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  text-align: center;
  color: var(--color-text);
}

.section__subtitle {
  text-align: center;
  color: var(--color-text-secondary);
  margin-bottom: 3rem;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.section__title + .section__subtitle {
  margin-top: 0.75rem;
}

/* =============================================
   Buttons
   ============================================= */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.7rem 1.5rem;
  font-family: var(--font-body);
  font-size: 0.9rem;
  font-weight: 500;
  border-radius: var(--radius-full);
  border: 2px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.btn--primary {
  background-color: var(--color-primary);
  color: #ffffff;
  border-color: var(--color-primary);
}

.btn--primary:hover {
  background-color: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
  color: #ffffff;
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

.btn--secondary {
  background-color: var(--color-accent);
  color: #ffffff;
  border-color: var(--color-accent);
}

.btn--secondary:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(6, 182, 212, 0.3);
  color: #ffffff;
}

.btn--outline {
  background-color: transparent;
  color: var(--color-text);
  border-color: var(--color-border);
}

.btn--outline:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  transform: translateY(-2px);
}

.btn--full {
  width: 100%;
  justify-content: center;
}

/* =============================================
   Header / Navigation
   ============================================= */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background-color: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  transition: background-color var(--transition-normal), box-shadow var(--transition-normal);
}

.header.scrolled {
  box-shadow: 0 2px 20px var(--color-shadow);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 70px;
}

.nav__logo {
  font-family: var(--font-mono);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-primary);
}

.nav__logo:hover {
  color: var(--color-primary-dark);
}

.nav__list {
  display: flex;
  gap: 2rem;
}

.nav__link {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  position: relative;
  padding: 0.25rem 0;
}

.nav__link::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-primary);
  transition: width var(--transition-fast);
}

.nav__link:hover,
.nav__link.active {
  color: var(--color-primary);
}

.nav__link:hover::after,
.nav__link.active::after {
  width: 100%;
}

.nav__actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

/* Theme Toggle */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border: none;
  border-radius: var(--radius-sm);
  background-color: transparent;
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

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

.icon--moon {
  display: none;
}

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

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

/* Mobile Toggle */
.nav__toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  border: none;
  background: transparent;
  cursor: pointer;
  padding: 8px;
}

.nav__toggle span {
  display: block;
  width: 100%;
  height: 2px;
  background-color: var(--color-text);
  border-radius: 2px;
  transition: all var(--transition-fast);
}

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

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

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

/* =============================================
   Hero Section
   ============================================= */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  background: var(--color-hero-gradient);
  padding-top: 70px;
}

.hero__content {
  max-width: 700px;
}

.hero__greeting {
  font-size: 1.1rem;
  color: var(--color-primary);
  font-weight: 500;
  margin-bottom: 0.5rem;
}

.hero__name {
  font-size: clamp(2.5rem, 6vw, 4rem);
  font-weight: 700;
  color: var(--color-text);
  line-height: 1.1;
  margin-bottom: 0.75rem;
}

.hero__title {
  font-size: clamp(1.1rem, 3vw, 1.5rem);
  font-weight: 500;
  color: var(--color-text-secondary);
  margin-bottom: 1.5rem;
}

.hero__tagline {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  max-width: 550px;
  margin-bottom: 2rem;
  line-height: 1.8;
}

.hero__cta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

/* =============================================
   About Section
   ============================================= */
.about__content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  margin-top: 3rem;
  align-items: start;
}

.about__text p {
  color: var(--color-text-secondary);
  margin-bottom: 1rem;
}

.about__text p:last-child {
  margin-bottom: 0;
}

.about__tech h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 1rem;
  color: var(--color-text);
}

.tech-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.badge {
  display: inline-block;
  padding: 0.35rem 0.85rem;
  font-size: 0.8rem;
  font-weight: 500;
  border-radius: var(--radius-full);
  background-color: var(--color-badge-bg);
  color: var(--color-badge-text);
  transition: all var(--transition-fast);
}

.badge:hover {
  transform: translateY(-1px);
}

.badge--sm {
  padding: 0.25rem 0.65rem;
  font-size: 0.75rem;
}

/* =============================================
   Skills Section
   ============================================= */
.skills__grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
  margin-top: 3rem;
}

.skill-card {
  background-color: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  transition: all var(--transition-normal);
}

.skill-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 30px var(--color-shadow-hover);
}

.skill-card__icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  background-color: var(--color-primary-bg);
  color: var(--color-primary);
  margin-bottom: 1.25rem;
}

.skill-card__title {
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 1.25rem;
  color: var(--color-text);
}

.skill-card__list {
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
}

.skill-card__list li {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.skill-card__list li span {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  font-weight: 500;
}

.skill-bar {
  width: 100%;
  height: 6px;
  background-color: var(--color-skill-bar-bg);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.skill-bar__fill {
  height: 100%;
  background-color: var(--color-skill-bar-fill);
  border-radius: var(--radius-full);
  width: 0;
  transition: width 1s ease-out;
}

/* =============================================
   Projects Section
   ============================================= */
.project-featured {
  background: var(--color-featured-bg);
  border-radius: var(--radius-lg);
  padding: 2.5rem;
  color: #ffffff;
  margin-top: 3rem;
  margin-bottom: 2rem;
  position: relative;
  overflow: hidden;
}

.project-featured::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 300px;
  height: 300px;
  background: rgba(255, 255, 255, 0.05);
  border-radius: 50%;
}

.project-featured__badge {
  display: inline-block;
  padding: 0.3rem 0.85rem;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  background-color: rgba(255, 255, 255, 0.2);
  border-radius: var(--radius-full);
  margin-bottom: 1rem;
}

.project-featured__title {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 1rem;
}

.project-featured__desc {
  font-size: 1rem;
  line-height: 1.7;
  opacity: 0.9;
  margin-bottom: 1.25rem;
  max-width: 700px;
}

.project-featured__tech {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.25rem;
}

.project-featured__tech .badge {
  background-color: rgba(255, 255, 255, 0.15);
  color: #ffffff;
}

.project-featured__status {
  font-size: 0.85rem;
  opacity: 0.7;
  font-style: italic;
}

/* Project Cards */
.projects__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.project-card {
  background-color: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  display: flex;
  flex-direction: column;
  transition: all var(--transition-normal);
}

.project-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 30px var(--color-shadow-hover);
}

.project-card__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.25rem;
  color: var(--color-primary);
}

.project-card__links {
  display: flex;
  gap: 0.75rem;
}

.project-card__links a {
  color: var(--color-text-muted);
  transition: color var(--transition-fast);
}

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

.project-card__title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
  color: var(--color-text);
}

.project-card__desc {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
  flex-grow: 1;
  margin-bottom: 1.25rem;
}

.project-card__tech {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.project-card__tech span {
  font-size: 0.75rem;
  font-family: var(--font-mono);
  color: var(--color-text-muted);
}

/* =============================================
   Blog Section
   ============================================= */
.blog__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  margin-top: 3rem;
}

.blog-card {
  background-color: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  transition: all var(--transition-normal);
}

.blog-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 30px var(--color-shadow-hover);
}

.blog-card__date {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  font-weight: 500;
  margin-bottom: 0.75rem;
}

.blog-card__title {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
  line-height: 1.4;
}

.blog-card__title a {
  color: var(--color-text);
  transition: color var(--transition-fast);
}

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

.blog-card__excerpt {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 1rem;
}

.blog-card__link {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-primary);
}

.blog-card__link:hover {
  color: var(--color-primary-dark);
}

.blog__more {
  text-align: center;
  margin-top: 2.5rem;
}

/* =============================================
   Contact Section
   ============================================= */
.contact__content {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 3rem;
  margin-top: 3rem;
}

.contact__info {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.contact__item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  color: var(--color-text-secondary);
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}

.contact__item:hover {
  background-color: var(--color-primary-bg);
  color: var(--color-primary);
}

.contact__item svg {
  flex-shrink: 0;
}

/* Form */
.contact__form {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.form__group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.form__label {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-text-secondary);
}

.form__input {
  padding: 0.75rem 1rem;
  font-family: var(--font-body);
  font-size: 0.95rem;
  color: var(--color-text);
  background-color: var(--color-input-bg);
  border: 1px solid var(--color-input-border);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.form__input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-bg);
}

.form__textarea {
  resize: vertical;
  min-height: 120px;
}

/* =============================================
   Footer
   ============================================= */
.footer {
  background-color: var(--color-footer-bg);
  color: var(--color-footer-text);
  text-align: center;
  padding: 2rem 0;
  font-size: 0.85rem;
}

.footer__sub {
  margin-top: 0.35rem;
  font-size: 0.75rem;
  opacity: 0.6;
}

/* =============================================
   Scroll Animations
   ============================================= */
.animate-on-scroll {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.animate-on-scroll.visible {
  opacity: 1;
  transform: translateY(0);
}

/* =============================================
   Responsive Design
   ============================================= */

/* Tablet */
@media (max-width: 768px) {
  :root {
    --section-padding: 4rem 0;
  }

  .nav__list {
    position: fixed;
    top: 70px;
    left: 0;
    right: 0;
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    flex-direction: column;
    align-items: center;
    padding: 2rem 0;
    gap: 1.5rem;
    transform: translateY(-150%);
    transition: transform var(--transition-normal);
    z-index: 99;
  }

  .nav__list.active {
    transform: translateY(0);
  }

  .nav__toggle {
    display: flex;
  }

  .hero__content {
    max-width: 100%;
  }

  .about__content {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

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

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

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

  .contact__content {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .hero__cta {
    flex-direction: column;
    align-items: flex-start;
  }

  .hero__cta .btn {
    width: 100%;
    justify-content: center;
  }
}

/* Small Mobile */
@media (max-width: 480px) {
  :root {
    --section-padding: 3rem 0;
    --container-padding: 1rem;
  }

  .section__title {
    font-size: 1.6rem;
  }

  .project-featured {
    padding: 1.5rem;
  }

  .project-featured__title {
    font-size: 1.35rem;
  }

  .skill-card {
    padding: 1.5rem;
  }

  .project-card {
    padding: 1.5rem;
  }

  .blog-card {
    padding: 1.5rem;
  }
}

/* Large Desktop */
@media (min-width: 1200px) {
  :root {
    --container-max: 1200px;
  }
}