:root {
    --primary-color: #2c3e50;
    --secondary-color: #34495e;
    --accent-color: #3498db;
    --bg-color: #f4f7f6;
    --text-color: #333;
    --white: #ffffff;
    --linen: #faf0e6;
    --max-width: 1100px;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 20px;
}

header {
    background-color: var(--white);
    padding: 20px 0;
    margin-bottom: 20px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 20px;
}

.logo-section {
    display: flex;
    align-items: center;
    gap: 20px;
}

.logo-section img {
    max-width: 150px;
    height: auto;
}

.header-text h3 {
    margin: 0;
    color: var(--primary-color);
}

.oval-image {
    width: 180px;
    height: 180px;
    border-radius: 50%;
    object-fit: cover;
    border: 3px solid var(--accent-color);
}

main {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-bottom: 40px;
}

section {
    background: var(--white);
    padding: 25px;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
}

section h3 {
    margin-top: 0;
    color: var(--secondary-color);
    border-bottom: 2px solid var(--accent-color);
    padding-bottom: 10px;
    margin-bottom: 20px;
}

ul {
    padding-left: 20px;
}

ul li {
    margin-bottom: 10px;
}

.problems-solved {
    grid-column: 1 / -1;
    background-color: var(--linen);
}

.problems-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.problems-grid ul {
    margin: 0;
}

@media (max-width: 768px) {
    header .container {
        flex-direction: column;
        text-align: center;
    }
    
    .logo-section {
        flex-direction: column;
    }
}