/* =========================================
   Design Tokens
   ========================================= */
:root {
  /* Colors */
  --color-bg: #fafafa;
  --color-bg-alt: #f0f0f0;
  --color-text: #1a1a1a;
  --color-text-muted: #6b6b6b;
  --color-accent: #6366f1;
  --color-accent-hover: #4f46e5;
  --color-border: rgba(0, 0, 0, 0.08);
  --color-card-bg: #ffffff;

  /* Typography */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.5rem;
  --font-size-2xl: 2rem;
  --font-size-3xl: 3rem;
  --font-size-4xl: 4.5rem;

  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2.5rem;
  --space-xl: 4rem;
  --space-2xl: 6rem;
  --space-3xl: 10rem;

  /* Misc */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --nav-height: 72px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
}

ul {
  list-style: none;
}

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

button,
input,
textarea {
  font-family: inherit;
  font-size: inherit;
  border: none;
  outline: none;
  background: none;
}

/* =========================================
   Container
   ========================================= */
.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 var(--space-md);
}

/* =========================================
   Navigation
   ========================================= */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  z-index: 1000;
  background: rgba(250, 250, 250, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--color-border);
  transition: box-shadow var(--transition);
}

.nav--scrolled {
  box-shadow: 0 1px 20px rgba(0, 0, 0, 0.06);
}

.nav__inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 var(--space-md);
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav__logo {
  font-weight: 700;
  font-size: var(--font-size-xl);
  letter-spacing: -0.02em;
  color: var(--color-accent);
  transition: opacity var(--transition);
}

.nav__logo:hover {
  opacity: 0.7;
}

.nav__links {
  display: flex;
  gap: var(--space-lg);
}

.nav__links a {
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text-muted);
  transition: color var(--transition);
  position: relative;
}

.nav__links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--color-accent);
  border-radius: 1px;
  transition: width var(--transition);
}

.nav__links a:hover,
.nav__links a.active {
  color: var(--color-text);
}

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

/* Hamburger */
.nav__toggle {
  display: none;
  flex-direction: column;
  gap: 6px;
  cursor: pointer;
  padding: 4px;
  z-index: 1001;
}

.nav__toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}

.nav__toggle.active span:first-child {
  transform: translateY(4px) rotate(45deg);
}

.nav__toggle.active span:last-child {
  transform: translateY(-4px) rotate(-45deg);
}

/* =========================================
   Hero
   ========================================= */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  position: relative;
  padding-top: var(--nav-height);
}

.hero__content {
  padding: var(--space-2xl) 0;
}

.hero__greeting {
  font-size: var(--font-size-lg);
  font-weight: 400;
  color: var(--color-accent);
  margin-bottom: var(--space-xs);
  letter-spacing: 0.02em;
}

.hero__name {
  font-size: var(--font-size-4xl);
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1.1;
  margin-bottom: var(--space-md);
  background: linear-gradient(135deg, var(--color-text) 0%, var(--color-text-muted) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero__tagline {
  font-size: var(--font-size-xl);
  font-weight: 300;
  color: var(--color-text-muted);
  margin-bottom: var(--space-xl);
  max-width: 500px;
}

.hero__cta {
  display: flex;
  gap: var(--space-sm);
}

.hero__scroll-indicator {
  position: absolute;
  bottom: var(--space-lg);
  left: 50%;
  transform: translateX(-50%);
}

.hero__scroll-line {
  width: 1px;
  height: 60px;
  background: linear-gradient(to bottom, var(--color-accent), transparent);
  animation: scrollPulse 2s ease-in-out infinite;
}

@keyframes scrollPulse {
  0%, 100% { opacity: 0.3; transform: scaleY(0.6); }
  50% { opacity: 1; transform: scaleY(1); }
}

/* =========================================
   Buttons
   ========================================= */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 32px;
  border-radius: var(--radius-sm);
  font-weight: 500;
  font-size: var(--font-size-sm);
  cursor: pointer;
  transition: all var(--transition);
  letter-spacing: 0.01em;
}

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

.btn--primary:hover {
  background: var(--color-accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(99, 102, 241, 0.3);
}

.btn--ghost {
  border: 1.5px solid var(--color-border);
  color: var(--color-text);
}

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

.btn--full {
  width: 100%;
}

/* =========================================
   Sections
   ========================================= */
.section {
  padding: var(--space-3xl) 0;
}

.section__title {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: var(--space-xl);
  position: relative;
  display: inline-block;
}

.section__title::after {
  content: '';
  position: absolute;
  bottom: -8px;
  left: 0;
  width: 40px;
  height: 3px;
  background: var(--color-accent);
  border-radius: 2px;
}

/* =========================================
   About
   ========================================= */
.about__content {
  max-width: 640px;
}

.about__content p {
  font-size: var(--font-size-lg);
  color: var(--color-text-muted);
  line-height: 1.8;
  margin-bottom: var(--space-md);
}

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

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

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

.project-card {
  background: var(--color-card-bg);
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--color-border);
  transition: transform var(--transition), box-shadow var(--transition);
  cursor: pointer;
}

.project-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.08);
}

.project-card__image {
  aspect-ratio: 16 / 10;
  background: linear-gradient(135deg, #e8e8e8 0%, #f5f5f5 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  position: relative;
}

.project-card__placeholder {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  color: rgba(0, 0, 0, 0.06);
  letter-spacing: -0.02em;
  transition: color var(--transition), transform var(--transition);
}

.project-card:hover .project-card__placeholder {
  color: var(--color-accent);
  transform: scale(1.1);
}

.project-card__info {
  padding: var(--space-md) var(--space-md) var(--space-lg);
}

.project-card__info h3 {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: var(--space-xs);
  letter-spacing: -0.01em;
}

.project-card__info p {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  line-height: 1.6;
  margin-bottom: var(--space-sm);
}

.project-card__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.project-card__tags span {
  font-size: var(--font-size-xs);
  padding: 4px 10px;
  background: var(--color-bg-alt);
  border-radius: 100px;
  color: var(--color-text-muted);
  font-weight: 500;
}

/* =========================================
   Skills
   ========================================= */
.skills__grid {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  max-width: 640px;
}

.skill-tag {
  font-size: var(--font-size-sm);
  font-weight: 500;
  padding: 10px 22px;
  border: 1.5px solid var(--color-border);
  border-radius: 100px;
  color: var(--color-text-muted);
  transition: all var(--transition);
  cursor: default;
}

.skill-tag:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  background: rgba(99, 102, 241, 0.04);
  transform: translateY(-2px);
}

/* =========================================
   Contact
   ========================================= */
.contact {
  text-align: center;
}

.contact .section__title::after {
  left: 50%;
  transform: translateX(-50%);
}

.contact__subtitle {
  font-size: var(--font-size-lg);
  color: var(--color-text-muted);
  margin-bottom: var(--space-xl);
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
}

.contact__form {
  max-width: 500px;
  margin: 0 auto var(--space-xl);
  text-align: left;
}

.form__group {
  margin-bottom: var(--space-sm);
}

.form__group input,
.form__group textarea {
  width: 100%;
  padding: 14px 18px;
  background: var(--color-card-bg);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text);
  transition: border-color var(--transition), box-shadow var(--transition);
}

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

.form__group input:focus,
.form__group textarea:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

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

.contact__socials {
  display: flex;
  justify-content: center;
  gap: var(--space-md);
}

.contact__socials a {
  color: var(--color-text-muted);
  transition: color var(--transition), transform var(--transition);
  padding: 8px;
}

.contact__socials a:hover {
  color: var(--color-accent);
  transform: translateY(-3px);
}

/* =========================================
   Footer
   ========================================= */
.footer {
  padding: var(--space-lg) 0;
  border-top: 1px solid var(--color-border);
  text-align: center;
}

.footer p {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
}

/* =========================================
   Reveal Animation
   ========================================= */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.7s cubic-bezier(0.4, 0, 0.2, 1),
              transform 0.7s cubic-bezier(0.4, 0, 0.2, 1);
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Stagger children */
.reveal:nth-child(2) { transition-delay: 0.1s; }
.reveal:nth-child(3) { transition-delay: 0.2s; }
.reveal:nth-child(4) { transition-delay: 0.3s; }

/* =========================================
   Responsive
   ========================================= */
@media (max-width: 768px) {
  :root {
    --font-size-4xl: 2.8rem;
    --font-size-3xl: 2rem;
    --font-size-2xl: 1.5rem;
  }

  .nav__toggle {
    display: flex;
  }

  .nav__links {
    position: fixed;
    top: 0;
    right: 0;
    width: 100%;
    height: 100vh;
    background: rgba(250, 250, 250, 0.97);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: var(--space-xl);
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition), visibility var(--transition);
  }

  .nav__links.open {
    opacity: 1;
    visibility: visible;
  }

  .nav__links a {
    font-size: var(--font-size-xl);
  }

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

  .hero__cta {
    flex-direction: column;
  }

  .hero__cta .btn {
    text-align: center;
  }
}

@media (max-width: 480px) {
  :root {
    --font-size-4xl: 2.2rem;
    --space-3xl: 6rem;
  }
}