:root {
  --bg-color: #0f172a;
  --text-color: #f1f5f9;
  --header-bg: #1e293b;
  --accent: #38bdf8;
  --accent-hover: #0ea5e9;
  --card-bg: #1e293b;
}
body.light-mode {
  --bg-color: #ffffff;
  --text-color: #1e293b;
  --header-bg: #f8fafc;
  --card-bg: #f1f5f9;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: 'Poppins', sans-serif;
  background: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
  transition: background 0.3s ease, color 0.3s ease;
}
header {
  background: var(--header-bg);
  padding: 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: 0 2px 6px rgba(0,0,0,0.1);
  transition: background 0.3s ease;
}
header h1 {
  font-size: 24px;
  color: var(--accent);
}
.nav-toggle {
  display: none;
  font-size: 28px;
  color: var(--text-color);
  cursor: pointer;
  background: none;
  border: none;
  transition: transform 0.3s ease;
}
.nav-toggle:active {
  transform: rotate(90deg);
}
nav {
  display: flex;
  align-items: center;
  gap: 20px;
  transition: all 0.3s ease;
}
nav a {
  color: var(--text-color);
  text-decoration: none;
  font-weight: 500;
  position: relative;
  transition: color 0.3s ease;
}
nav a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -3px;
  width: 0;
  height: 2px;
  background-color: var(--accent);
  transition: width 0.3s;
}
nav a:hover::after {
  width: 100%;
}
nav a:hover {
  color: var(--accent);
}
.lang-switch, .theme-toggle {
  background: #334155;
  border: none;
  padding: 6px 12px;
  border-radius: 6px;
  color: #f1f5f9;
  cursor: pointer;
  transition: background 0.3s ease, transform 0.3s ease;
}
.lang-switch:hover, .theme-toggle:hover {
  background: #475569;
  transform: scale(1.05);
}
.hero {
  text-align: center;
  padding: 100px 20px 60px;
  background: radial-gradient(circle at top, #1e3a8a 0%, var(--bg-color) 100%);
}
.hero h2 {
  font-size: 44px;
  font-weight: 600;
  margin-bottom: 20px;
}
.hero p {
  font-size: 18px;
  margin-bottom: 30px;
  color: #cbd5e1;
}
.hero .btn-primary, .hero .btn-secondary {
  padding: 12px 30px;
  border-radius: 8px;
  font-size: 16px;
  text-decoration: none;
  margin: 5px;
  display: inline-block;
  transition: transform 0.2s ease, background 0.3s ease;
}
.btn-primary {
  background-color: var(--accent);
  color: var(--bg-color);
}
.btn-primary:hover {
  background-color: var(--accent-hover);
  transform: scale(1.05);
}
.btn-secondary {
  background-color: transparent;
  border: 1px solid var(--accent);
  color: var(--accent);
}
.btn-secondary:hover {
  background-color: var(--header-bg);
  transform: scale(1.05);
}
.features, .how-it-works {
  padding: 60px 20px;
  max-width: 1100px;
  margin: auto;
}
.features h3, .how-it-works h3 {
  text-align: center;
  font-size: 28px;
  margin-bottom: 40px;
  color: var(--accent);
}
.features-grid, .how-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 25px;
}
.feature, .how-step {
  background: var(--card-bg);
  border-radius: 12px;
  padding: 25px;
  text-align: center;
  box-shadow: 0 4px 15px rgba(0,0,0,0.05);
  transition: background 0.3s ease, color 0.3s ease;
}
.feature h4, .how-step h4 {
  font-size: 20px;
  margin-bottom: 15px;
  color: var(--accent);
}
.feature p, .how-step p {
  color: var(--text-color);
}
.card-icon {
  width: 48px;
  height: 48px;
  margin-bottom: 15px;
  filter: brightness(1.1) saturate(1.2);
  object-fit: contain;
}
@media (max-width: 768px) {
  .card-icon {
    width: 32px;
    height: 32px;
    margin-bottom: 10px;
  }
}
.feature:hover .card-icon,
.how-step:hover .card-icon {
  transform: scale(1.1);
}
footer {
  text-align: center;
  padding: 40px 20px;
  font-size: 14px;
  color: #94a3b8;
  border-top: 1px solid #334155;
  margin-top: 60px;
  background: var(--header-bg);
  transition: background 0.3s ease;
}
footer a {
  color: var(--accent);
  text-decoration: none;
  font-size: 14px;
  margin: 0 8px;
}

footer a:hover {
  text-decoration: underline;
  color: var(--accent-hover);
}

@media (max-width: 768px) {
nav {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    background: var(--header-bg);
    position: absolute;
    top: 70px;
    right: 20px;
    padding: 0;
    border-radius: 10px;
    box-shadow: 0 8px 20px rgba(0,0,0,0.2);
    max-height: 0;
    overflow: hidden;
    opacity: 0;
    transform: scaleY(0.95);
    transform-origin: top right;
    transition: max-height 0.4s ease, opacity 0.4s ease, transform 0.4s ease, padding 0.3s ease;
}

nav.active {
    padding: 20px;
    max-height: 500px; /* yeterli yüksekliği belirle */
    opacity: 1;
    transform: scaleY(1);
    pointer-events: auto;
}

.nav-toggle {
    display: block;
}
}