* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    background: #0f172a;
    color: #e2e8f0;
    font-family: Arial, sans-serif;
    line-height: 1.6;
}

header {
    text-align: center;
    padding: 70px 20px 50px;
    background: linear-gradient(180deg, #0b1220, #0f172a);
    border-bottom: 1px solid #1e293b;
}

header h1 {
    font-size: 42px;
    margin-bottom: 12px;
    color: #ffffff;
    letter-spacing: -1px;
}

header p {
    color: #94a3b8;
    font-size: 16px;
}

main {
    max-width: 900px;
    margin: auto;
    padding: 40px 20px;
}

.topic {
    background: #111827;
    border: 1px solid #1f2937;
    border-radius: 12px;
    margin-bottom: 25px;
    overflow: hidden;
    transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.topic:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(0,0,0,0.25);
}

.topic-header {
    padding: 18px 22px;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.topic-header h2 {
    font-size: 18px;
    color: #38bdf8;
}

.topic-header:hover {
    background: #1f2937;
}

.topic-body {
    padding: 22px;
    border-top: 1px solid #1f2937;
}

.cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
    gap: 18px;
}

.card {
    background: #1e293b;
    padding: 18px;
    border-radius: 10px;
    border: 1px solid #263244;
    transition: transform 0.15s ease, background 0.15s ease;
}

.card:hover {
    transform: translateY(-3px);
    background: #273449;
}

.card h3 {
    margin-bottom: 8px;
    color: #ffffff;
    font-size: 16px;
}

.card p {
    font-size: 14px;
    color: #94a3b8;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 20px;
    border-radius: 8px;
    overflow: hidden;
}

th, td {
    padding: 12px 14px;
    border-bottom: 1px solid #1f2937;
    text-align: left;
}

th {
    background: #0b1220;
    color: #38bdf8;
    font-size: 13px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

tr:hover {
    background: #1e293b;
}

button {
    padding: 7px 14px;
    background: transparent;
    border: 1px solid #334155;
    color: #38bdf8;
    border-radius: 6px;
    cursor: pointer;
    font-size: 13px;
    transition: all 0.15s ease;
}

button:hover {
    background: #1f2937;
    border-color: #38bdf8;
}

.badge {
    display: inline-block;
    font-size: 11px;
    padding: 4px 10px;
    border-radius: 20px;
    background: #1e293b;
    color: #38bdf8;
    margin-bottom: 15px;
}

footer {
    text-align: center;
    padding: 30px 20px;
    color: #64748b;
    font-size: 13px;
    border-top: 1px solid #1e293b;
}