/* ===== PROBLEM STATEMENTS PAGE STYLES ===== */

/* Logo link styling */
.logo-link {
    text-decoration: none;
    color: inherit;
}

.logo-link:hover .glow-text {
    text-shadow: 0 0 15px var(--primary-neon), 0 0 25px var(--primary-neon), 0 0 35px var(--primary-neon);
}

/* ===== PROBLEMS HERO SECTION ===== */
.problems-hero {
    min-height: 80vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: radial-gradient(ellipse at center, rgba(0, 255, 255, 0.1) 0%, transparent 70%);
    position: relative;
    padding-top: 100px;
}

.problems-hero .hero-content {
    text-align: center;
    max-width: 900px;
    padding: 0 20px;
}

.problems-hero .hero-title {
    font-family: var(--font-primary);
    font-size: clamp(2.5rem, 6vw, 4.5rem);
    font-weight: 900;
    margin-bottom: 20px;
    line-height: 1.1;
}

.problems-hero .hero-subtitle {
    background: var(--gradient-secondary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-size: clamp(1.5rem, 4vw, 2.5rem);
    animation: glow-pulse 2s ease-in-out infinite alternate;
}

.problems-hero .hero-description {
    font-size: clamp(1rem, 2.5vw, 1.3rem);
    color: var(--text-secondary);
    margin-bottom: 40px;
    line-height: 1.8;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 60px;
    margin-top: 50px;
}

.stat-item {
    text-align: center;
    padding: 20px;
    border-radius: var(--border-radius);
    background: rgba(26, 26, 26, 0.6);
    border: 1px solid rgba(0, 255, 255, 0.2);
    transition: all var(--transition-fast);
}

.stat-item:hover {
    transform: translateY(-5px);
    border-color: var(--primary-neon);
    box-shadow: 0 10px 20px rgba(0, 255, 255, 0.2);
}

.stat-number {
    display: block;
    font-family: var(--font-primary);
    font-size: 2.5rem;
    font-weight: 900;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 5px;
}

.stat-label {
    color: var(--text-secondary);
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

/* ===== FILTER SECTION ===== */
.filter-section {
    padding: 60px 0 40px;
    background: rgba(17, 17, 17, 0.8);
}

.filter-controls {
    text-align: center;
}

.filter-controls h3 {
    font-family: var(--font-primary);
    color: var(--primary-neon);
    margin-bottom: 30px;
    font-size: 1.5rem;
}

.filter-buttons {
    display: flex;
    justify-content: center;
    gap: 15px;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 10px 20px;
    background: transparent;
    border: 2px solid rgba(0, 255, 255, 0.3);
    border-radius: 25px;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-fast);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.filter-btn:hover,
.filter-btn.active {
    border-color: var(--primary-neon);
    color: var(--primary-neon);
    background: rgba(0, 255, 255, 0.1);
    box-shadow: 0 0 15px rgba(0, 255, 255, 0.3);
}

/* ===== PROBLEMS GRID ===== */
.problems-grid-section {
    padding: var(--section-padding);
    background: var(--primary-bg);
}

.problems-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 30px;
    margin-top: 40px;
}

.problem-card {
    background: rgba(26, 26, 26, 0.9);
    border: 1px solid rgba(0, 255, 255, 0.2);
    border-radius: var(--border-radius);
    padding: 25px;
    transition: all var(--transition-medium);
    position: relative;
    overflow: hidden;
    cursor: pointer;
}

.problem-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--gradient-primary);
    opacity: 0;
    transition: opacity var(--transition-fast);
    z-index: -1;
}

.problem-card:hover::before {
    opacity: 0.05;
}

.problem-card:hover {
    transform: translateY(-8px);
    border-color: var(--primary-neon);
    box-shadow: 0 20px 40px rgba(0, 255, 255, 0.2);
}

/* Hidden cards for filtering */
.problem-card.hidden {
    display: none;
}

.problem-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.problem-number {
    font-family: var(--font-primary);
    font-size: 1.5rem;
    font-weight: 900;
    color: var(--primary-neon);
    background: rgba(0, 255, 255, 0.1);
    padding: 8px 15px;
    border-radius: 20px;
    border: 1px solid var(--primary-neon);
}

.problem-category {
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-muted);
    background: rgba(255, 255, 255, 0.05);
    padding: 5px 12px;
    border-radius: 15px;
}

.difficulty-badge {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    padding: 4px 10px;
    border-radius: 12px;
    letter-spacing: 0.5px;
}

.difficulty-badge.easy {
    background: rgba(0, 255, 0, 0.2);
    color: #00ff00;
    border: 1px solid #00ff00;
}

.difficulty-badge.medium {
    background: rgba(255, 255, 0, 0.2);
    color: #ffff00;
    border: 1px solid #ffff00;
}

.difficulty-badge.hard {
    background: rgba(255, 0, 0, 0.2);
    color: #ff0080;
    border: 1px solid #ff0080;
}

.problem-title {
    font-family: var(--font-primary);
    font-size: 1.4rem;
    color: var(--text-primary);
    margin-bottom: 15px;
    line-height: 1.3;
}

.problem-description {
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 20px;
    font-size: 0.95rem;
}

.problem-tags {
    display: flex;
    gap: 8px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.tag {
    background: rgba(0, 255, 255, 0.1);
    color: var(--primary-neon);
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 0.75rem;
    border: 1px solid rgba(0, 255, 255, 0.3);
    font-weight: 500;
}

.problem-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: auto;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.estimated-time {
    color: var(--text-muted);
    font-size: 0.85rem;
    display: flex;
    align-items: center;
    gap: 5px;
}

.select-btn {
    padding: 8px 20px;
    background: transparent;
    border: 2px solid var(--secondary-neon);
    border-radius: 25px;
    color: var(--secondary-neon);
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.select-btn:hover {
    background: var(--secondary-neon);
    color: var(--primary-bg);
    box-shadow: 0 0 20px var(--secondary-neon);
    transform: translateY(-2px);
}

.select-btn.selected {
    background: var(--gradient-secondary);
    border-color: var(--tertiary-neon);
    color: var(--primary-bg);
    box-shadow: 0 0 25px var(--tertiary-neon);
}

/* ===== PROBLEMS CTA SECTION ===== */
.problems-cta {
    padding: var(--section-padding);
    background: linear-gradient(135deg, rgba(17, 17, 17, 0.9), rgba(0, 0, 0, 0.8));
    text-align: center;
}

.problems-cta .cta-title {
    font-family: var(--font-primary);
    font-size: clamp(2rem, 4vw, 3rem);
    margin-bottom: 20px;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.problems-cta .cta-description {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 40px;
    line-height: 1.8;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 768px) {
    .hero-stats {
        flex-direction: column;
        gap: 20px;
        align-items: center;
    }
    
    .stat-item {
        width: 200px;
    }
    
    .filter-buttons {
        gap: 10px;
    }
    
    .filter-btn {
        padding: 8px 15px;
        font-size: 0.8rem;
    }
    
    .problems-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .problem-card {
        padding: 20px;
    }
    
    .problem-header {
        flex-wrap: wrap;
        gap: 10px;
    }
    
    .problem-footer {
        flex-direction: column;
        gap: 15px;
        align-items: flex-start;
    }
    
    .select-btn {
        width: 100%;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .problems-hero {
        min-height: 70vh;
        padding-top: 80px;
    }
    
    .stat-number {
        font-size: 2rem;
    }
    
    .filter-buttons {
        justify-content: center;
    }
    
    .problem-card {
        padding: 15px;
    }
    
    .problem-title {
        font-size: 1.2rem;
    }
    
    .problem-tags {
        gap: 5px;
    }
    
    .tag {
        font-size: 0.7rem;
        padding: 3px 8px;
    }
}

/* ===== ANIMATIONS ===== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.problem-card {
    animation: fadeInUp 0.6s ease-out;
}

.problem-card:nth-child(odd) {
    animation-delay: 0.1s;
}

.problem-card:nth-child(even) {
    animation-delay: 0.2s;
}

/* ===== FILTER ANIMATIONS ===== */
.problem-card.filtering {
    transition: all 0.4s ease;
}

.problem-card.fade-out {
    opacity: 0;
    transform: scale(0.8);
}

.problem-card.fade-in {
    opacity: 1;
    transform: scale(1);
}