/* --- Google Font Import --- */
@import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@400;500;600&display=swap');

/* --- CSS Variables for a Dark Theme --- */
:root {
    --font-family: 'JetBrains Mono', monospace;
    
    /* Dark Theme Palette */
    --bg-color: #34383e;         /* Main background (dark grey) */
    --card-bg-color: #21262d;    /* Card background (slightly lighter grey) */
    --border-color: #30363d;     /* Borders and dividers */
    --shadow-color: rgba(0, 0, 0, 0.2);
    
    --text-primary: #ffffff;     /* Primary text (off-white) */
    --text-secondary: #c8cdd4;   /* Secondary/dimmed text */
    
    --accent-color: #58a6ff;      /* Links and interactive elements (soft blue) */
    --accent-color-hover: #ffffff; /* Text color on hover for accent elements */
    
    /* Tag Colors */
    --tag-easy-bg: rgba(46, 160, 67, 0.15);
    --tag-easy-text: #3fb950;
    --tag-medium-bg: rgba(187, 128, 9, 0.15);
    --tag-medium-text: #d29922;
    --tag-hard-bg: rgba(248, 81, 73, 0.15);
    --tag-hard-text: #f85149;
}

/* --- Global Styles --- */
body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-primary);
    margin: 0;
    padding: 2rem;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* --- Main Container & Typography --- */
.container {
    max-width: 900px;
    margin: 0 auto;
}

h1 {
    text-align: center;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.subtitle {
    text-align: center;
    color: var(--text-secondary);
    margin-top: 0;
    margin-bottom: 3rem;
}

/* --- Filter Controls --- */
.filters {
    display: flex;
    gap: 1.5rem;
    margin-bottom: 3rem;
    justify-content: center;
    flex-wrap: wrap;
}

.filter-group label {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.filters select {
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    font-family: var(--font-family);
    background-color: var(--card-bg-color);
    color: var(--text-primary);
    min-width: 220px;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.filters select:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.2);
}

/* --- Question Card Styling --- */
#questions-list {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.question-card {
    padding: 1.5rem;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    background-color: var(--card-bg-color);
    box-shadow: 0 1px 2px var(--shadow-color);
    transition: transform 0.2s ease, border-color 0.2s ease;
}

.question-card:hover {
    transform: translateY(-4px);
    border-color: var(--accent-color);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.card-header h3 {
    margin: 0;
    font-size: 1.2rem;
    font-weight: 500;
    line-height: 1.4;
    color: var(--text-primary);
}

.tags {
    display: flex;
    gap: 0.5rem;
    flex-shrink: 0; /* Prevents tags from shrinking on smaller screens */
}

.tag {
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.8rem;
    font-weight: 500;
}

.topic-tag {
    background-color: #30363d;
    color: var(--text-secondary);
}

.difficulty-tag.Easy { background-color: var(--tag-easy-bg); color: var(--tag-easy-text); }
.difficulty-tag.Medium { background-color: var(--tag-medium-bg); color: var(--tag-medium-text); }
.difficulty-tag.Hard { background-color: var(--tag-hard-bg); color: var(--tag-hard-text); }

.card-body {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.links a {
    text-decoration: none;
    color: var(--accent-color);
    background-color: transparent;
    padding: 0.5rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    margin-right: 0.5rem;
    font-weight: 500;
    transition: background-color 0.2s, color 0.2s, border-color 0.2s;
}

.links a:hover {
    background-color: var(--accent-color);
    color: var(--accent-color-hover);
    border-color: var(--accent-color);
}

.feedback {
    display: flex;
    align-items: center;
    gap: 1rem;
    color: var(--text-secondary);
}

.feedback span {
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.feedback .fa-thumbs-up { color: var(--tag-easy-text); }
.feedback .fa-thumbs-down { color: var(--tag-hard-text); }

/* --- Solved Question Styling --- */

/* Styles the entire card when it's marked as solved */
.question-card.solved {
    /* Fades the card to de-emphasize it */
    opacity: 0.6;
    /* Adds a green accent bar on the left for a clear visual cue */
    border-left: 4px solid var(--tag-easy-text); 
}

/* Brings the card back to full opacity on hover so it's easy to read and uncheck */
.question-card.solved:hover {
    opacity: 1;
}

/* --- Checkbox and Title Container Styling --- */

/* A flex container to align the checkbox and the question title neatly */
.title-container {
    display: flex;
    align-items: center;
    gap: 1rem;
}

/* Styles the checkbox itself */
.solved-checkbox {
    /* Makes the checkbox slightly larger and easier to click */
    width: 1.2rem;
    height: 1.2rem;
    
    /* A modern CSS property to color the checkmark and background when ticked */
    accent-color: var(--tag-easy-text);
    
    /* Ensures the checkbox doesn't shrink if the title is long */
    flex-shrink: 0;

    /* Changes the cursor to a pointer to indicate it's clickable */
    cursor: pointer;
}