body {
    font-family: 'Roboto', Arial, sans-serif;
    background: linear-gradient(120deg, #e0e7ff 0%, #f0f4f9 100%);
    margin: 0;
    padding: 0;
    min-height: 100vh;
    color: #222;
}

header {
    padding: 2rem 1rem 1rem 1rem;
    text-align: center;
}

h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: #3b82f6;
    letter-spacing: -1px;
}

header p {
    color: #666;
    margin: 0 0 1rem 0;
    font-size: 1.1rem;
}

.certificates-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

.certificate-card {
    background: #fff;
    border-radius: 16px;
    border: 2.5px solid #2563eb; /* Rectangle frame */
    box-shadow: 0 4px 24px rgba(60,100,170,0.09);
    padding: 1.5rem 1rem 2rem 1rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    transition: transform 0.18s cubic-bezier(.4,0,.2,1), box-shadow 0.15s;
    outline: none;
    position: relative;
}

.certificate-card:hover,
.certificate-card:focus-within {
    transform: translateY(-6px) scale(1.025);
    box-shadow: 0 8px 32px rgba(60,100,170,0.18);
    border-color: #1e40af;
}

.certificate-card h2 {
    font-size: 1.23rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: #2563eb;
    text-align: center;
    min-height: 48px;
    line-height: 1.25;
}

.certificate-card img {
    width: 100%;
    max-width: 320px;
    border-radius: 10px;
    margin-bottom: 1rem;
    box-shadow: 0 2px 8px rgba(44,62,80,0.09);
    border: 2px solid #e5e7eb;
    background: #f6f8fa;
    transition: box-shadow 0.18s, border-color 0.15s;
    object-fit: cover;
    aspect-ratio: 16 / 11;
}

.certificate-card img:hover,
.certificate-card img:focus {
    box-shadow: 0 6px 24px rgba(44,62,80,0.18);
    border-color: #2563eb;
}

.btn {
    background: linear-gradient(90deg, #2563eb 75%, #4f8cff 100%);
    color: #fff;
    text-decoration: none;
    font-weight: 600;
    padding: 0.65rem 1.5rem;
    border-radius: 6px;
    margin-top: 0.5rem;
    transition: background 0.19s, box-shadow 0.15s, transform 0.16s;
    box-shadow: 0 2px 8px rgba(60,100,170,0.12);
    letter-spacing: 0.01em;
    border: none;
    outline: none;
}

.btn:hover,
.btn:focus {
    background: linear-gradient(90deg, #1e40af 75%, #2563eb 100%);
    box-shadow: 0 4px 16px rgba(37,99,235,0.18);
    transform: translateY(-2px) scale(1.035);
}

@media (max-width: 900px) {
    .certificates-grid {
        grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    }
}

@media (max-width: 600px) {
    h1 { font-size: 2rem; }
    .certificate-card h2 { font-size: 1rem; }
    .certificate-card img { max-width: 98vw; }
    .certificates-grid { gap: 1.2rem; padding: 1rem 0.1rem;}
    .certificate-card { padding: 1rem 0.4rem 1.2rem 0.4rem;}
}