/* CSS Variables for Light & Dark Themes */
:root {
  --bg-color: #f8fafc;
  --surface-color: #ffffff;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --accent-color: #2563eb;
  --border-color: #e2e8f0;
}

body.dark-mode {
  --bg-color: #0f172a;
  --surface-color: #1e293b;
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --accent-color: #38bdf8;
  --border-color: #334155;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: system-ui, -apple-system, sans-serif;
}

body {
  background-color: var(--bg-color);
  color: var(--text-primary);
  line-height: 1.6;
  transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header & Navigation */
#main-header {
  background-color: var(--surface-color);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
}

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

.logo {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--text-primary);
  text-decoration: none;
}

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

.nav-links {
  display: flex;
  list-style: none;
  gap: 2rem;
}

.nav-links a {
  text-decoration: none;
  color: var(--text-secondary);
  font-weight: 500;
}

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

.nav-actions button {
  background: none;
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 0.4rem 0.7rem;
  border-radius: 6px;
  cursor: pointer;
  margin-left: 0.5rem;
}

#menu-toggle {
  display: none;
}

/* Hero Section */
#hero {
  padding: 5rem 1.5rem;
}

.subtitle {
  color: var(--accent-color);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  font-size: 0.85rem;
  margin-bottom: 0.5rem;
}

h1 {
  font-size: 2.75rem;
  line-height: 1.2;
  margin-bottom: 1rem;
}

.bio {
  color: var(--text-secondary);
  max-width: 600px;
  margin-bottom: 2rem;
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  border-radius: 6px;
  text-decoration: none;
  font-weight: 600;
  cursor: pointer;
  border: none;
}

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

.secondary-btn {
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  margin-left: 0.75rem;
}

/* Cards & Grid */
section {
  padding: 3rem 0;
}

h2 {
  font-size: 1.75rem;
  margin-bottom: 1.5rem;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem;
}

.card {
  background-color: var(--surface-color);
  border: 1px solid var(--border-color);
  padding: 1.5rem;
  border-radius: 10px;
}

.card h3 {
  margin-bottom: 0.5rem;
}

.card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

/* Filter Buttons (Projects Page) */
.filter-buttons {
  margin: 1.5rem 0;
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.filter-btn {
  padding: 0.5rem 1rem;
  border: 1px solid var(--border-color);
  background: var(--surface-color);
  color: var(--text-primary);
  border-radius: 20px;
  cursor: pointer;
}

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

.tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--accent-color);
  margin-bottom: 0.5rem;
}

/* Contact Form */
.contact-form {
  max-width: 550px;
  background: var(--surface-color);
  padding: 2rem;
  border-radius: 10px;
  border: 1px solid var(--border-color);
}

.form-group {
  margin-bottom: 1.25rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.4rem;
  font-weight: 500;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 0.7rem;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  background: var(--bg-color);
  color: var(--text-primary);
}

.feedback-msg {
  margin-top: 1rem;
  font-weight: 500;
  color: var(--accent-color);
}

/* Footer */
footer {
  border-top: 1px solid var(--border-color);
  padding: 2rem 0;
  margin-top: 3rem;
  text-align: center;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

/* Mobile Responsive Navigation */
@media (max-width: 768px) {
  #menu-toggle {
    display: inline-block;
  }

  .nav-links {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 70px;
    left: 0;
    width: 100%;
    background: var(--surface-color);
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
  }

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