:root {
  /* Kurumsal Light Theme */
  --bg: #F8FAFC;             /* Çok Açık Slate */
  --bg-secondary: #FFFFFF;
  --text-main: #0F172A;      /* Koyu Slate (Yüksek Okunabilirlik) */
  --text-dim: #475569;       /* Orta Slate */
  --primary: #008080;        /* Kurumsal Turkuaz */
  --secondary: #004B63;      /* Orta Mavi */
  --dark: #001F3D;           /* Koyu Lacivert */
  --accent-light: #F1F5F9;
  --white: #FFFFFF;
  --glass-bg: rgba(255, 255, 255, 0.85);
  --glass-border: rgba(0, 128, 128, 0.1);
  --btn-text: #FFFFFF;
  --shadow: 0 10px 25px rgba(0,0,0,0.05);
  
  --gradient: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  --font-main: 'Inter', sans-serif;
  --font-header: 'Montserrat', sans-serif;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Kurumsal Dark Theme Overrides */
[data-theme='dark'] {
  --bg: #0F172A;             /* Slate 900 */
  --bg-secondary: #1E293B;   /* Slate 800 */
  --text-main: #F1F5F9;      /* Slate 100 */
  --text-dim: #94A3B8;       /* Slate 400 */
  --primary: #2DD4BF;        /* Modern Teal */
  --secondary: #0D9488;      /* Deep Teal */
  --dark: #020617;           /* En Koyu Slate */
  --accent-light: #334155;
  --white: #FFFFFF;
  --glass-bg: rgba(30, 41, 59, 0.7);
  --glass-border: rgba(45, 212, 191, 0.15);
  --btn-text: #0F172A;
  --shadow: 0 20px 40px rgba(0,0,0,0.4);
  
  --gradient: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
}

/* Auto Dark Mode */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme='light']) {
    --bg: #0F172A;
    --bg-secondary: #1E293B;
    --text-main: #F1F5F9;
    --text-dim: #94A3B8;
    --primary: #2DD4BF;
    --secondary: #0D9488;
    --dark: #020617;
    --accent-light: #334155;
    --white: #FFFFFF;
    --glass-bg: rgba(30, 41, 59, 0.7);
    --glass-border: rgba(45, 212, 191, 0.15);
    --btn-text: #0F172A;
    --shadow: 0 20px 40px rgba(0,0,0,0.4);
    --gradient: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  }
}

* { margin: 0; padding: 0; box-sizing: border-box; }
body { 
    font-family: var(--font-main); 
    background-color: var(--bg); 
    color: var(--text-main); 
    line-height: 1.6; 
    transition: background-color var(--transition), color var(--transition);
}

/* Layout */
.header { 
    display: flex; 
    justify-content: space-between; 
    align-items: center; 
    padding: 1rem 5%; 
    background: var(--dark);
    color: #F1F5F9;
    border-bottom: 1px solid var(--accent-light); 
    position: sticky; 
    top: 0; 
    z-index: 1000; 
    transition: background var(--transition);
}
.logo img { height: 60px; transition: filter var(--transition); }
[data-theme='dark'] .logo img { filter: brightness(1.2); }
.nav-links { display: flex; gap: 2rem; align-items: center; }
.nav-links a { text-decoration: none; color: inherit; font-weight: 500; font-size: 0.9rem; transition: var(--transition); }
.nav-links a:hover { color: var(--primary); }

.header-right { 
    display: flex; 
    align-items: center; 
    gap: 1.5rem; 
    margin-left: auto; 
}

/* Theme Toggle */
.theme-toggle {
    background: none;
    border: 1px solid var(--accent-light);
    color: inherit;
    padding: 0.5rem;
    border-radius: 50%;
    cursor: pointer;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}
.theme-toggle:hover { background: rgba(255,255,255,0.1); border-color: var(--primary); color: var(--primary); }

/* Hero Section */
.hero { 
    display: flex; 
    align-items: center; 
    text-align: center;
    height: 90vh; 
    padding: 4rem 5%; 
    background-image: linear-gradient(to bottom, rgba(248, 250, 252, 0.85) 0%, rgba(248, 250, 252, 0.95) 100%), url('resources/hero_bg.png');
    background-repeat: no-repeat;
    background-size: cover;
    background-position: center;
    transition: background var(--transition);
}

/* Dark Mode Hero */
[data-theme='dark'] .hero {
    background-image: linear-gradient(to bottom, rgba(15, 23, 42, 0.85) 0%, rgba(15, 23, 42, 0.95) 100%), url('resources/hero_bg.png');
}

.hero-content { 
    flex: 1;
    max-width: 900px;
    margin: 0 auto;
}
.hero-title { 
    font-family: var(--font-header); 
    font-size: 4rem; 
    line-height: 1.1; 
    margin-bottom: 1.5rem; 
    color: var(--text-main);
    letter-spacing: -1px;
}
.hero-title span { background: var(--gradient); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }
.hero-description { font-size: 1.25rem; color: var(--text-dim); margin-bottom: 2.5rem; font-weight: 450; max-width: 700px; margin-left: auto; margin-right: auto; }

/* Grid Sections */
.section-title { text-align: center; font-family: var(--font-header); margin-bottom: 3.5rem; font-size: 2.5rem; color: var(--text-main); }
.container { padding: 5rem 5%; }
.grid-features { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 2rem; }
.card { 
    background: var(--bg-secondary); 
    padding: 2.5rem; 
    border-radius: 16px; 
    border: 1px solid var(--accent-light); 
    transition: var(--transition); 
    box-shadow: var(--shadow);
}
.card:hover { 
    transform: translateY(-8px); 
    box-shadow: 0 20px 40px rgba(0,0,0,0.08); 
    border-color: var(--primary); 
}
[data-theme='dark'] .card {
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    border-color: var(--glass-border);
}

.card i { font-size: 2rem; color: var(--primary); margin-bottom: 1.5rem; display: block; }
.card h3 { margin-bottom: 1rem; font-size: 1.4rem; color: var(--text-main); }
.card p { font-size: 1rem; color: var(--text-dim); }

/* Pricing */
.pricing-grid { display: flex; gap: 2rem; justify-content: center; flex-wrap: wrap; }
.price-card { 
    background: var(--bg-secondary); 
    padding: 3.5rem 2.5rem; 
    border-radius: 24px; 
    width: 350px; 
    text-align: center; 
    border: 1px solid var(--accent-light); 
    transition: var(--transition);
    box-shadow: var(--shadow);
}
.price-card.popular { border: 2.5px solid var(--primary); position: relative; transform: scale(1.05); }
.price-card h4 { font-size: 1.75rem; margin-bottom: 1rem; color: var(--text-main); }
.price-card p { color: var(--text-dim); font-size: 1.1rem; }

/* Buttons */
.btn { padding: 1rem 2.5rem; border-radius: 10px; border: none; font-weight: 600; cursor: pointer; transition: var(--transition); text-decoration: none; display: inline-block; font-size: 1rem; }
.btn-primary { background: var(--primary); color: var(--btn-text); }
.btn-dark { background: var(--dark); color: #FFFFFF; }
.btn-primary:hover, .btn-dark:hover { filter: brightness(1.1); transform: translateY(-3px); box-shadow: 0 10px 20px rgba(0,0,0,0.1); }

/* Utility Classes */
.section-modüller { background: var(--accent-light); border-radius: 60px 60px 0 0; }
.footer { background: var(--dark); color: #F1F5F9; text-align: center; }
.footer-dim { margin: 1.5rem 0; opacity: 0.8; }
.ml-1 { margin-left: 1.5rem; }

@media (max-width: 768px) {
    .hero-title { font-size: 2.75rem; }
    .header { padding: 1rem 5%; }
}