:root {
    --primary-bg: #0a192f;
    --secondary-bg: #112240;
    --sidebar-bg: #020c1b;
    --text-main: #e6f1ff;
    --text-muted: #8892b0;
    --accent-color: #64ffda;
    --card-radius: 16px;
    --transition: all 0.3s ease;

    /* Gradients */
    --grad-1: linear-gradient(135deg, #1e3a8a 0%, #7e22ce 100%); /* Navy to Purple */
    --grad-2: linear-gradient(135deg, #7e22ce 0%, #ec4899 100%); /* Purple to Pink */
    --grad-3: linear-gradient(135deg, #06b6d4 0%, #3b82f6 100%); /* Turquoise to Blue */
    --grad-4: linear-gradient(135deg, #f59e0b 0%, #ef4444 100%); /* Orange to Red */
    
    --grad-dark: linear-gradient(135deg, #112240 0%, #0a192f 100%);
}

body {
    background-color: var(--primary-bg);
    color: var(--text-main);
    font-family: 'Inter', 'Outfit', sans-serif;
    margin: 0;
    padding: 0;
    overflow-x: hidden;
}

/* Layout Containers */
.app-container {
    display: flex;
    min-height: 100vh;
}

.sidebar {
    width: 260px;
    background-color: var(--sidebar-bg);
    border-right: 1px solid rgba(255, 255, 255, 0.1);
    height: 100vh;
    position: fixed;
    left: 0;
    top: 0;
    z-index: 100;
    transition: var(--transition);
}

.main-content {
    flex: 1;
    margin-left: 260px;
    padding: 20px;
    transition: var(--transition);
}

.topbar {
    height: 70px;
    display: flex;
    align-items: center;
    justify-content: flex-end;
    padding: 0 30px;
    background: rgba(10, 25, 47, 0.85);
    backdrop-filter: blur(10px);
    position: sticky;
    top: 0;
    z-index: 90;
    margin-bottom: 20px;
}

/* Cards */
.stat-card {
    border-radius: var(--card-radius);
    padding: 24px;
    color: white;
    box-shadow: 0 10px 30px -15px rgba(2, 12, 27, 0.7);
    transition: var(--transition);
    border: none;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.stat-card:hover {
    transform: translateY(-5px);
}

.stat-card.g1 { background: var(--grad-1); }
.stat-card.g2 { background: var(--grad-2); }
.stat-card.g3 { background: var(--grad-3); }
.stat-card.g4 { background: var(--grad-4); }

.card-title {
    font-size: 0.9rem;
    font-weight: 500;
    opacity: 0.8;
    margin-bottom: 10px;
}

.card-value {
    font-size: 1.8rem;
    font-weight: 700;
}

/* Buttons */
.btn-premium {
    background: var(--accent-color);
    color: var(--primary-bg);
    border: none;
    padding: 10px 24px;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    display: inline-block;
}

.btn-premium:hover {
    box-shadow: 0 0 15px var(--accent-color);
    transform: scale(1.05);
}

/* Login Page Specifics */
.login-bg-video {
    position: fixed;
    right: 0;
    bottom: 0;
    min-width: 100%;
    min-height: 100%;
    z-index: -1;
    object-fit: cover;
}

.login-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(2, 12, 27, 0.6);
    display: flex;
    align-items: center;
    justify-content: center;
}

.login-card {
    background: rgba(17, 34, 64, 0.75);
    backdrop-filter: blur(15px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 20px;
    padding: 40px;
    width: 100%;
    max-width: 400px;
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.5);
}

/* Charts */
.chart-container {
    background: var(--secondary-bg);
    border-radius: var(--card-radius);
    padding: 20px;
    margin-top: 30px;
    border: 1px solid rgba(255, 255, 255, 0.05);
}

/* Responsive */
@media (max-width: 992px) {
    .sidebar {
        transform: translateX(-100%);
    }
    .main-content {
        margin-left: 0;
    }
    .sidebar.active {
        transform: translateX(0);
    }
}

/* Exercise Specifics */
.exercise-engine-container {
    background: var(--card-bg);
    border-radius: 24px;
    box-shadow: var(--shadow-lg);
}

.exercise-display-area {
    background: var(--sidebar-bg);
    border-radius: 20px;
    min-height: 400px;
    position: relative;
    border: 1px solid rgba(255,255,255,0.05);
}

.KelimeClass {
    position: absolute;
    color: var(--text-main);
    font-weight: 600;
    transition: all 0.1s ease;
    text-shadow: 0 0 10px rgba(100, 255, 218, 0.3);
}

.BlokKelime {
    display: inline-block;
    padding: 2px 5px;
    border-radius: 4px;
    transition: all 0.2s ease;
}

.BlokKelime.aktif {
    background: var(--accent-color);
    color: var(--primary-bg);
}

.BlokKelime.pasif {
    opacity: 0.1;
}

.BlokKelime.GrupAktif {
    background: var(--grad-2);
    color: white;
}

/* Category Cards */
.category-card {
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.category-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
}

/* Custom Progress Bar for Exercises */
.exercise-progress {
    height: 8px;
    border-radius: 4px;
    background: rgba(255,255,255,0.1);
    overflow: hidden;
}

.exercise-progress-bar {
    height: 100%;
    background: var(--grad-1);
    transition: width 0.3s linear;
}