* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: "Segoe UI", Arial, sans-serif;
    font-size: 17px;
    line-height: 1.6;
    color: #1f2933;
    background: #f4f6fb;
}

header {
    background: linear-gradient(135deg, #2b5876, #4e4376);
    color: #fff;
    padding: 32px 16px 24px;
    text-align: center;
}

header h1 {
    margin: 0 0 6px;
    font-size: 30px;
}

header p {
    margin: 0;
    opacity: 0.85;
}

nav {
    background: #ffffff;
    border-bottom: 1px solid #dde3ee;
    position: sticky;
    top: 0;
    z-index: 10;
}

nav ul {
    list-style: none;
    margin: 0 auto;
    padding: 0 16px;
    max-width: 900px;
    display: flex;
    flex-wrap: wrap;
    gap: 4px;
}

nav a {
    display: block;
    padding: 14px 16px;
    color: #2b5876;
    text-decoration: none;
    font-weight: 600;
    border-bottom: 3px solid transparent;
}

nav a:hover {
    background: #eef2f9;
}

nav a.active {
    border-bottom-color: #4e4376;
    color: #4e4376;
}

main {
    max-width: 900px;
    margin: 0 auto;
    padding: 24px 16px 40px;
}

h2 {
    color: #2b5876;
    margin-top: 36px;
    border-left: 5px solid #4e4376;
    padding-left: 12px;
}

.card {
    background: #fff;
    border-radius: 10px;
    padding: 16px 20px;
    margin: 14px 0;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.06);
}

.card h3 {
    margin: 0 0 6px;
    color: #4e4376;
}

.card p {
    margin: 0;
}

.note {
    background: #fff8e1;
    border-left: 5px solid #f5b400;
    padding: 12px 16px;
    border-radius: 6px;
    margin: 18px 0;
}

.timeline {
    position: relative;
    margin: 20px 0;
    padding-left: 28px;
    border-left: 3px solid #4e4376;
}

.event {
    position: relative;
    margin-bottom: 22px;
}

.event::before {
    content: "";
    position: absolute;
    left: -37px;
    top: 6px;
    width: 15px;
    height: 15px;
    border-radius: 50%;
    background: #fff;
    border: 3px solid #4e4376;
}

.year {
    display: inline-block;
    background: #4e4376;
    color: #fff;
    font-weight: 700;
    padding: 2px 10px;
    border-radius: 12px;
    font-size: 15px;
}

.event h3 {
    margin: 6px 0 4px;
}

.event p {
    margin: 0;
}

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 14px;
}

.grid .card {
    margin: 0;
}

ol li,
ul li {
    margin-bottom: 6px;
}

.next {
    display: inline-block;
    margin-top: 28px;
    padding: 10px 20px;
    background: #4e4376;
    color: #fff;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 600;
}

.next:hover {
    background: #2b5876;
}

footer {
    text-align: center;
    padding: 20px 16px;
    color: #6b7280;
    font-size: 14px;
    border-top: 1px solid #dde3ee;
    background: #fff;
}

@media (max-width: 600px) {
    header h1 {
        font-size: 24px;
    }

    nav a {
        padding: 10px 10px;
        font-size: 15px;
    }
}