* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: Arial, sans-serif;
    background: #f4f6f8;
    color: #1f2937;
}

.container {
    max-width: 1000px;
    margin: 40px auto;
    padding: 0 20px 30px;
}

h1 {
    margin: 0 0 24px;
    text-align: center;
    font-size: clamp(1.4rem, 2.8vw, 1.75rem);
    line-height: 1.25;
}

.portal-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
    gap: 16px;
    width: 90%;
    margin: 0 auto;
}

.portal-link {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 110px;
    padding: 16px;
    text-decoration: none;
    color: #ffffff;
    background: #3674f8;
    border-radius: 10px;
    font-size: clamp(1rem, 2.5vw, 1.35rem);
    font-weight: bold;
    transition: background 0.2s ease;
    text-align: center;
}

.portal-link:hover {
    background: #16a34a;
}

.portal-link:active {
    background: #15803d;
}

@media (max-width: 768px) {
    .container {
        margin: 24px auto;
        padding: 0 14px 24px;
    }

    .portal-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
        gap: 12px;
    }

    .portal-link {
        min-height: 90px;
        border-radius: 8px;
    }
}

@media (max-width: 480px) {
    .container {
        margin: 16px auto;
        padding: 0 10px 16px;
    }

    h1 {
        margin-bottom: 16px;
    }

    .portal-grid {
        grid-template-columns: 1fr;
        gap: 10px;
    }

    .portal-link {
        min-height: 72px;
        font-size: 1rem;
    }
}