/* ===========================================
   PROOF TYPES & EXTENDED COMPONENTS
   =========================================== */

/* Problem Grid - Extended to 6 cards */
.problem-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-xl);
    margin-bottom: var(--space-3xl);
}

@media (max-width: 768px) {
    .problem-grid {
        grid-template-columns: 1fr;
    }
}

/* Proof Types Grid - NEW */
.proof-types-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--space-xl);
    margin-top: var(--space-3xl);
}

@media (max-width: 1200px) {
    .proof-types-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .proof-types-grid {
        grid-template-columns: 1fr;
    }
}

.proof-type-card {
    position: relative;
    background: white;
    border-radius: var(--radius-lg);
    padding: var(--space-xl);
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    border: 2px solid transparent;
}

.proof-type-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-light);
}

.proof-type-number {
    position: absolute;
    top: var(--space-lg);
    right: var(--space-lg);
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    border-radius: 50%;
    font-weight: 800;
    font-size: 1.125rem;
    box-shadow: var(--shadow);
}

.proof-type-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 64px;
    height: 64px;
    background: var(--gray-50);
    border-radius: var(--radius);
    color: var(--primary);
    margin-bottom: var(--space-lg);
    transition: var(--transition);
}

.proof-type-card:hover .proof-type-icon {
    background: var(--primary);
    color: white;
    transform: scale(1.1);
}

.proof-type-card h3 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: var(--space-sm);
    line-height: 1.3;
}

.proof-type-card p {
    color: var(--gray-600);
    line-height: 1.6;
    margin: 0;
}

/* ===========================================
   NAVBAR - Modern & Sticky
   =========================================== */

header {
    position: sticky;
    top: 0;
    z-index: 9999;
    width: 100%;
}

.navbar {
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--gray-200);
    padding: var(--space-md) 0;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.navbar-sticky {
    position: sticky;
    top: 0;
    z-index: 9999;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

.navbar-sticky.scrolled {
    padding: var(--space-sm) 0;
    box-shadow: var(--shadow-md);
    background: rgba(255, 255, 255, 0.99);
}

.navbar .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-lg);
}

.navbar-brand {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    text-decoration: none;
    color: var(--gray-900);
    font-weight: 800;
    font-size: 1.25rem;
    transition: var(--transition);
}

.navbar-brand:hover {
    color: var(--primary);
}

.navbar-menu {
    display: flex;
    align-items: center;
    gap: var(--space-xl);
    flex: 1;
    justify-content: center;
}

@media (max-width: 1024px) {
    .navbar-menu {
        display: none;
    }
}