:root {
    --bg-color: #212529;
    --dark-text: #212529;
    --light-text: #f8f9fa;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --border-radius: 12px;
    --transition: all 0.5s ease;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Montserrat', sans-serif;
    background-color: var(--bg-color);
    color: var(--dark-text);
    min-height: 100vh;
    padding: 2rem;
}

.app-container {
    max-width: 1200px;
    margin: 0 auto;
}

.app-header {
    text-align: center;
    margin-bottom: 2rem;
}

.app-title {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    color: var(--light-text);
}

.app-subtitle {
    font-size: 1.1rem;
    color: var(--light-text);
}

.flashcard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
    padding: 1rem;
}

/* Flashcard styles */
.flashcard {
    perspective: 1000px;
    height: 400px;
    position: relative;
}

/* Hide checkbox but keep it functional */
.flashcard-checkbox {
    position: absolute;
    opacity: 0;
    height: 100%;
    width: 100%;
    cursor: pointer;
    z-index: 2;
}

/* Card container */
.flashcard-inner {
    position: relative;
    width: 100%;
    height: 100%;
    transition: var(--transition);
    transform-style: preserve-3d;
    cursor: pointer;
}

/* Flip when checkbox is checked */
.flashcard-checkbox:checked ~ .flashcard-inner {
    transform: rotateY(180deg);
}
/* Shared face styles */
.flashcard-face {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: var(--border-radius);
    padding: 2rem;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    box-shadow: var(--shadow);
    text-align: center;
    color: var(--light-text);
    border: 2px solid #ffffff;
}

/* Front face specific styles */
.flashcard-front {
    background-image: url('bg-desktop.jpg');
    background-size: cover;
    background-position: center;
}

/* Back face specific styles */
.flashcard-back {
    background-image: url('bg-desktop.jpg');
    background-size: cover;
    background-position: center;
    transform: rotateY(180deg);
}

/* Card content styling */
.flashcard h2 {
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.flashcard p {
    font-size: 1.1rem;
    line-height: 1.6;
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .flashcard-grid {
        grid-template-columns: 1fr;
    }
    
    .flashcard {
        height: 350px;
    }
    
    .app-title {
        font-size: 2rem;
    }
}