body {
    font-family: 'Poppins', sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f5f5f0;
    color: #333;
    transition: background-color 0.3s ease, color 0.3s ease;
    line-height: 1.7;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

body.dark {
    background-color: #1a1a1a;
    color: #f4f4f4;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 40px;
    text-align: center;
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

h1 {
    margin-top: 10px;
    margin-bottom: 30px;
    font-size: 2.2em;
    color: #007bff;
    font-weight: 600;
}

body.dark h1 {
    color: #61dafb;
}

/* Theme Toggle Button */
.theme-btn {
    background-color: #007bff;
    color: white;
    border: none;
    padding: 12px 24px;
    font-size: 1em;
    font-weight: 500;
    border-radius: 8px;
    cursor: pointer;
    margin-bottom: 20px;
    transition: background-color 0.3s ease, transform 0.2s ease;
    align-self: center;
    box-shadow: 0 2px 6px rgba(0, 123, 255, 0.3);
}

.theme-btn:hover {
    background-color: #0056b3;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 123, 255, 0.4);
}

body.dark .theme-btn {
    background-color: #61dafb;
    color: #1a1a1a;
    box-shadow: 0 2px 6px rgba(97, 218, 251, 0.3);
}

body.dark .theme-btn:hover {
    background-color: #21b4d6;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(97, 218, 251, 0.4);
}

/* Grid Layout */
.grid {
    display: flex;
    flex-wrap: nowrap;
    justify-content: center;
    gap: 20px;
    margin-top: 20px;
}

/* Cards */
.card {
    background-color: #fff;
    border: 1px solid #ddd;
    border-radius: 20px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    padding: 20px;
    text-align: left;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    flex: 0 0 calc(25% - 15px);
    min-width: 200px;
    min-height: 340px;
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    position: relative;
}

body.dark .card {
    background-color: #2d2d2d;
    border: 1px solid #555;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
}

.card:hover {
    transform: scale(1.05) translateY(-8px);
    box-shadow: 0 12px 28px rgba(0, 0, 0, 0.2), 0 0 20px rgba(0, 123, 255, 0.3);
    z-index: 10;
}

body.dark .card:hover {
    box-shadow: 0 12px 28px rgba(0, 0, 0, 0.6);
}

.card h2 {
    margin-top: 0;
    margin-bottom: 14px;
    font-size: 1.4em;
    color: #007bff;
    font-weight: 600;
}

body.dark .card h2 {
    color: #61dafb;
}

.card img {
    width: 100%;
    max-width: 180px;
    height: 80px;
    margin: 0 auto 16px auto;
    object-fit: contain;
    display: block;
    border-radius: 6px;
}

.card p {
    font-size: 0.95em;
    color: #555;
    flex-grow: 1;
    line-height: 1.7;
    text-align: justify;
}

body.dark .card p {
    color: #d0d0d0;
}

/* Popup Overlay */
.popup {
    position: absolute;
    bottom: 10px;
    left: 10px;
    right: 10px;
    background: rgba(0, 0, 0, 0.8);
    color: white;
    padding: 10px;
    border-radius: 10px;
    opacity: 0;
    transition: opacity 0.3s ease;
    pointer-events: none;
    font-size: 0.9em;
    text-align: center;
}

.card:hover .popup {
    opacity: 1;
}

/* Strong inside paragraphs */
.card p strong {
    color: #007bff;
    font-weight: 600;
}

body.dark .card p strong {
    color: #61dafb;
}

/* Responsive */
@media (max-width: 768px) {
    h1 {
        font-size: 1.8em;
    }
    .grid {
        flex-wrap: wrap;
        gap: 20px;
    }
    .card {
        flex: 1 1 250px;
        min-height: 320px;
        padding: 18px;
    }
    .card h2 {
        font-size: 1.3em;
    }
    .card p {
        font-size: 0.9em;
    }
    .theme-btn {
        font-size: 0.9em;
        padding: 10px 20px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 15px;
    }
    h1 {
        font-size: 1.5em;
    }
    .card {
        padding: 16px;
    }
}