.page-header {
    background: var(--dark-grey);
    text-align: center;
    padding: 4rem 1rem;
    border-bottom: 1px solid var(--medium-grey);
}

.page-header h1 {
    font-size: 3.5rem;
}

.page-header p {
    font-size: 1.2rem;
    color: var(--light-grey);
}

.design-section {
    padding-bottom: 4rem;
    text-align: center;
}
.section-intro {
    max-width: 800px;
    margin: 0 auto 3rem auto;
}

.evolution-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.evolution-card {
    background-color: var(--medium-grey);
    padding: 2.5rem 2rem;
    border-radius: 10px;
    border-top: 4px solid #555;
    transition: all 0.3s ease;
}

.evolution-card:first-child { border-color: #FFD700; }
.evolution-card:last-child { border-color: #4B0082; }

.evolution-card.central-card {
    transform: scale(1.05);
    background-color: #4a505a;
    border-top-color: var(--primary-color);
}

.evolution-card h3 {
    margin-bottom: 1rem;
    color: var(--white-text);
}

.design-details {
    max-width: 900px;
    margin: 0 auto;
}

.accordion-item {
    background-color: var(--medium-grey);
    margin-bottom: 10px;
    border-radius: 5px;
    overflow: hidden;
}

.accordion-header {
    background-color: transparent;
    color: var(--white-text);
    cursor: pointer;
    padding: 1.5rem;
    width: 100%;
    border: none;
    text-align: left;
    outline: none;
    font-size: 1.2rem;
    font-weight: 600;
    transition: background-color 0.3s ease;
    position: relative;
    font-family: 'Poppins', sans-serif;
}

.accordion-header::after {
    content: '+';
    font-size: 1.5rem;
    color: var(--primary-color);
    position: absolute;
    right: 1.5rem;
    top: 50%;
    transform: translateY(-50%);
    transition: transform 0.3s ease;
}

.accordion-header.active::after {
    content: '−';
    transform: translateY(-50%) rotate(180deg);
}

.accordion-header:hover, .accordion-header.active {
    background-color: #4a505a;
}

.accordion-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease-out;
    background: #2a2d34;
    padding: 0 1.5rem;
}
.accordion-content p {
    padding: 1rem 0;
}
.accordion-content p:first-child { padding-top: 1.5rem; }
.accordion-content p:last-child { padding-bottom: 1.5rem; }

/* Mobile Responsive Styles for Design Page */
@media (max-width: 800px) {
    .page-header {
        padding: 2.5rem 1rem;
    }
    .evolution-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    .evolution-card.central-card {
        transform: scale(1); /* Reset scaling */
    }
    .accordion-header {
        font-size: 1rem;
        padding: 1.2rem;
    }
}