* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: #0f172a;
    color: #ffffff;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: 20px;
}

h1 {
    font-size: 2rem;
    margin-bottom: 25px;
    color: #38bdf8;
    display: flex;
    align-items: center;
    gap: 10px;
}

.nav-buttons {
    display: flex;
    gap: 10px;
    margin-bottom: 25px;
}

.nav-btn {
    background-color: #1e293b;
    color: #94a3b8;
    border: 1px solid #334155;
    padding: 10px 20px;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s ease;
}

.nav-btn:hover {
    background-color: #334155;
    color: #fff;
}

.nav-btn.active {
    background-color: #0284c7;
    color: #ffffff;
    border-color: #38bdf8;
}

.card {
    background-color: #1e293b;
    border-radius: 12px;
    padding: 30px;
    width: 100%;
    max-width: 500px;
    text-align: center;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.3);
    border: 1px solid #334155;
    min-height: 250px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.game-section {
    display: none;
    width: 100%;
}

.game-section.active {
    display: block;
}

h2 {
    margin-bottom: 15px;
    font-size: 1.5rem;
}

p {
    color: #94a3b8;
    margin-bottom: 20px;
    font-size: 0.95rem;
}

.btn-group {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-top: 15px;
}

.game-btn {
    background-color: #38bdf8;
    color: #0f172a;
    border: none;
    padding: 10px 18px;
    border-radius: 6px;
    font-weight: bold;
    cursor: pointer;
    transition: transform 0.1s, background-color 0.2s;
}

.game-btn:hover {
    background-color: #7dd3fc;
    transform: translateY(-2px);
}

input[type="number"] {
    padding: 10px;
    border-radius: 6px;
    border: 1px solid #334155;
    background-color: #0f172a;
    color: #fff;
    text-align: center;
    width: 120px;
    margin-bottom: 15px;
    font-size: 1rem;
}

.result-text {
    margin-top: 15px;
    font-weight: bold;
    color: #38bdf8;
    min-height: 24px;
}

.back-link {
    margin-top: 30px;
    color: #64748b;
    text-decoration: none;
    font-size: 0.9rem;
    transition: color 0.2s;
}

.back-link:hover {
    color: #94a3b8;
}