/* ============================================================
   CSS Custom Properties
   ============================================================ */
:root {
  --color-bg: #0f172a;
  --color-bg-alt: #1e293b;
  --color-surface: #334155;
  --color-primary: #38bdf8;
  --color-primary-dark: #0ea5e9;
  --color-text: #e2e8f0;
  --color-text-muted: #94a3b8;
  --color-border: #334155;

  --font-sans: "Segoe UI", system-ui, -apple-system, sans-serif;
  --font-mono: "Courier New", monospace;

  --radius: 0.75rem;
  --transition: 0.3s ease;
  --max-width: 1100px;
  --nav-height: 64px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  min-height: 100vh;
}

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

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

ul {
  list-style: none;
}

/* ============================================================
   Utility
   ============================================================ */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin-inline: auto;
  padding-inline: 1.5rem;
}

.section {
  padding: 5rem 0;
}

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

.section-title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 700;
  margin-bottom: 3rem;
  position: relative;
  display: inline-block;
}

.section-title::after {
  content: "";
  display: block;
  height: 4px;
  width: 60%;
  background: var(--color-primary);
  border-radius: 2px;
  margin-top: 0.4rem;
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.65rem 1.5rem;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.95rem;
  transition: transform var(--transition), box-shadow var(--transition), background-color var(--transition);
  cursor: pointer;
  border: 2px solid transparent;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(56, 189, 248, 0.25);
}

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

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

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

.btn-secondary:hover {
  background-color: rgba(56, 189, 248, 0.1);
}

/* ============================================================
   Navigation
   ============================================================ */
#header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--nav-height);
  z-index: 100;
  transition: background-color var(--transition), box-shadow var(--transition);
}

#header.scrolled {
  background-color: rgba(15, 23, 42, 0.95);
  backdrop-filter: blur(12px);
  box-shadow: 0 1px 24px rgba(0, 0, 0, 0.5);
}

.navbar {
  max-width: var(--max-width);
  margin-inline: auto;
  padding-inline: 1.5rem;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--color-primary);
  letter-spacing: 0.05em;
}

.nav-links {
  display: flex;
  gap: 2rem;
}

.nav-links a {
  color: var(--color-text-muted);
  font-weight: 500;
  transition: color var(--transition);
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-primary);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--color-text);
  cursor: pointer;
}

/* ============================================================
   Hero
   ============================================================ */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: calc(var(--nav-height) + 2rem) 1.5rem 4rem;
  background: radial-gradient(ellipse 80% 60% at 50% 0%, rgba(56, 189, 248, 0.12), transparent);
}

.hero-content {
  max-width: 700px;
}

.hero-greeting {
  font-size: 1.1rem;
  color: var(--color-primary);
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 0.5rem;
}

.hero-name {
  font-size: clamp(2.5rem, 8vw, 5rem);
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, #e2e8f0 0%, var(--color-primary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-tagline {
  font-size: clamp(1rem, 2.5vw, 1.35rem);
  color: var(--color-text-muted);
  margin-bottom: 2.5rem;
}

.hero-actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* ============================================================
   About
   ============================================================ */
.about-content {
  max-width: 680px;
}

.about-text p {
  color: var(--color-text-muted);
  margin-bottom: 1.2rem;
  font-size: 1.05rem;
}

.about-text .btn {
  margin-top: 0.5rem;
}

/* ============================================================
   Skills
   ============================================================ */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.5rem;
}

.skill-card {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 2rem 1.5rem;
  transition: transform var(--transition), border-color var(--transition);
}

.skill-card:hover {
  transform: translateY(-4px);
  border-color: var(--color-primary);
}

.skill-icon {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}

.skill-card h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
  color: var(--color-text);
}

.skill-card ul {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.skill-card li {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  padding-left: 1rem;
  position: relative;
}

.skill-card li::before {
  content: "▸";
  position: absolute;
  left: 0;
  color: var(--color-primary);
}

/* ============================================================
   Projects
   ============================================================ */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

.project-card {
  background-color: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: transform var(--transition), border-color var(--transition);
}

.project-card:hover {
  transform: translateY(-4px);
  border-color: var(--color-primary);
}

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

.project-icon {
  font-size: 1.6rem;
}

.project-card h3 {
  font-size: 1.1rem;
  font-weight: 700;
}

.project-card > p {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  flex: 1;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.tag {
  background-color: rgba(56, 189, 248, 0.12);
  color: var(--color-primary);
  font-size: 0.78rem;
  font-weight: 600;
  padding: 0.2rem 0.6rem;
  border-radius: 999px;
}

.project-link {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-primary);
  display: inline-flex;
  align-items: center;
  gap: 0.2rem;
  transition: opacity var(--transition);
}

.project-link:hover {
  opacity: 0.8;
}

/* ============================================================
   Contact
   ============================================================ */
.contact-intro {
  color: var(--color-text-muted);
  font-size: 1.05rem;
  max-width: 560px;
  margin-bottom: 2.5rem;
}

.contact-links {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.contact-card {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1rem 1.5rem;
  font-weight: 600;
  transition: border-color var(--transition), transform var(--transition);
}

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

.contact-icon {
  font-size: 1.4rem;
}

/* ============================================================
   Footer
   ============================================================ */
.footer {
  text-align: center;
  padding: 2rem 1.5rem;
  color: var(--color-text-muted);
  font-size: 0.875rem;
  background-color: var(--color-bg);
  border-top: 1px solid var(--color-border);
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 640px) {
  .nav-links {
    display: none;
    flex-direction: column;
    background-color: var(--color-bg-alt);
    position: absolute;
    top: var(--nav-height);
    left: 0;
    width: 100%;
    padding: 1rem 1.5rem 1.5rem;
    gap: 1rem;
    border-bottom: 1px solid var(--color-border);
  }

  .nav-links.open {
    display: flex;
  }

  .nav-toggle {
    display: block;
  }

  .hero-actions {
    flex-direction: column;
    align-items: center;
  }
}