:root {
  --bg-color: #0f0f0f;
  --text-color: #fff;
  --accent-color: #ffd700;
  --card-bg: #1a1a1a;
  --hover-shadow: 0 0 20px #ffd70044;
  --btn-bg: #ffd700;
  --btn-text: #0f0f0f;
  --btn-hover-bg: #e6c200;
}

body.light-mode {
  --bg-color: #ffffff;
  --text-color: #111111;
  --accent-color: #007acc;
  --card-bg: #f3f3f3;
  --hover-shadow: 0 0 20px #007acc44;
  --btn-bg: #007acc;
  --btn-text: #fff;
  --btn-hover-bg: #005fa3;
}

body {
  font-family: 'Poppins', sans-serif;
  margin: 0;
  padding: 0;
  background-color: var(--bg-color);
  color: var(--text-color);
  transition: background 0.4s, color 0.4s;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

header {
  text-align: center;
  padding: 30px 20px;
  background-color: var(--card-bg);
  position: relative;
}

header h1 {
  margin: 0;
  font-size: 2.2em;
  color: var(--accent-color);
}

header p {
  margin: 5px 0 15px;
  font-size: 1.1em;
}

/* Tema değiştirme butonu */
#theme-toggle-btn {
  position: absolute;
  top: 20px;
  right: 20px;
  background-color: var(--btn-bg);
  color: var(--btn-text);
  border: none;
  padding: 10px 18px;
  border-radius: 30px;
  font-weight: 700;
  font-size: 1em;
  cursor: pointer;
  box-shadow: 0 0 10px var(--btn-bg);
  transition: background-color 0.3s ease, color 0.3s ease;
  user-select: none;
}

#theme-toggle-btn:hover,
#theme-toggle-btn:focus {
  background-color: var(--btn-hover-bg);
  outline: none;
}

/* Hero Bölümü */
.hero {
  background: linear-gradient(135deg, #1a1a1a 0%, #333333 100%);
  color: var(--accent-color);
  padding: 100px 20px 80px 20px;
  text-align: center;
  user-select: none;
  box-shadow: inset 0 0 60px #ffd70033;
}

.hero-content {
  max-width: 700px;
  margin: 0 auto;
}

.hero h2 {
  font-size: 2.8em;
  margin-bottom: 20px;
  font-weight: 700;
  text-shadow: 0 0 8px #ffd700aa;
  line-height: 1.2;
}

.hero p {
  font-size: 1.3em;
  margin-bottom: 35px;
  color: #f0e68ccc;
  font-weight: 500;
}

.btn-primary {
  background-color: var(--accent-color);
  color: var(--bg-color);
  font-weight: 700;
  padding: 15px 35px;
  font-size: 1.1em;
  border-radius: 40px;
  text-decoration: none;
  box-shadow: 0 0 15px var(--accent-color);
  transition: background-color 0.3s ease;
  user-select: none;
}

.btn-primary:hover,
.btn-primary:focus {
  background-color: #ccac00;
  outline: none;
}

/* Kartlar */
.cards {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 30px;
  padding: 20px 20px 40px 20px;
  max-width: 900px;
  margin: 60px auto 20px auto;
}

.hover-card {
  background-color: var(--card-bg);
  border-radius: 12px;
  padding: 20px;
  width: 280px;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  box-shadow: 0 0 0 transparent;
  cursor: pointer;
}

.hover-card:hover,
.hover-card:focus-within {
  transform: translateY(-8px);
  box-shadow: var(--hover-shadow);
}

.hover-card a {
  color: var(--text-color);
  text-decoration: none;
  display: block;
  outline-offset: 4px;
  padding: 15px 10px;
  border-radius: 10px;
  transition: background-color 0.3s ease;
}

.hover-card:hover a,
.hover-card:focus-within a {
  background-color: var(--accent-color);
  color: var(--bg-color);
}

/* Navigation */
nav {
  display: flex;
  justify-content: center;
  gap: 25px;
  background-color: var(--card-bg);
  padding: 15px 10px;
  flex-wrap: wrap;
  margin: 40px auto 40px auto;
  max-width: 900px;
  border-radius: 12px;
}

nav a {
  color: var(--accent-color);
  text-decoration: none;
  font-weight: 500;
  position: relative;
  font-size: 1.1em;
}

nav a::after {
  content: "";
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0%;
  height: 2px;
  background-color: var(--accent-color);
  transition: width 0.3s ease-in-out;
}

nav a:hover::after,
nav a:focus::after {
  width: 100%;
}

/* Bölümler */
.section-title {
  font-size: 1.5em;
  margin-top: 40px;
  border-bottom: 2px solid var(--accent-color);
  display: inline-block;
  padding-bottom: 5px;
}

section {
  padding: 20px;
  max-width: 900px;
  margin: 0 auto;
  flex: 1;
}

/* Footer */
footer {
  text-align: center;
  padding: 20px;
  background-color: var(--card-bg);
  font-size: 0.9em;
  margin-top: auto;
}

/* Geri Dön Butonu */
.back-button {
  display: inline-block;
  margin-top: 30px;
  padding: 10px 20px;
  background-color: var(--accent-color);
  color: var(--text-color);
  font-weight: 700;
  border: none;
  border-radius: 30px;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 0.3s ease;
  user-select: none;
  box-shadow: 0 0 10px var(--accent-color);
}

.back-button:hover,
.back-button:focus {
  background-color: #ccac00;
  outline: none;
}

/* Responsive */
@media (max-width: 600px) {
  .hero {
    padding: 70px 15px 50px 15px;
  }

  .hero h2 {
    font-size: 2em;
  }

  .hero p {
    font-size: 1.1em;
  }

  .btn-primary {
    padding: 12px 28px;
    font-size: 1em;
  }

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

  .hover-card {
    width: 90%;
  }

  nav {
    gap: 15px;
  }

  header h1 {
    font-size: 1.7em;
  }

  #theme-toggle-btn {
    top: 15px;
    right: 15px;
    padding: 8px 14px;
    font-size: 0.95em;
  }
}