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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: #e5e7eb;
    color: #1f2937;
    padding: 30px 20px;
}

h1 {
    text-align: center;
    margin-bottom: 40px;
    font-size: 2rem;
    color: #111827;
    letter-spacing: 0.5px;
}

#container {
    display: flex;
    flex-direction: column;
    gap: 25px;
}

.container {
    background: #ffffff;
    border-radius: 12px;
    padding: 20px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
    transition:
        transform 0.3s ease,
        box-shadow 0.3s ease;
}

.container:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.12);
}

.container h2 {
    font-size: 1.25rem;
    margin-bottom: 15px;
    color: #111827;
}

#markdown-input {
    width: 100%;
    min-height: 150px;
    padding: 15px;
    border-radius: 10px;
    border: 1px solid #d1d5db;
    font-size: 1rem;
    background: #f9fafb;
    resize: vertical;
    transition:
        border-color 0.3s ease,
        box-shadow 0.3s ease;
}

#markdown-input:focus {
    outline: none;
    border-color: #3b82f6;
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

#html-output,
#preview {
    width: 100%;
    min-height: 150px;
    padding: 15px;
    border-radius: 10px;
    background: #f3f4f6;
    border: 1px solid #d1d5db;
    font-family: monospace;
    font-size: 0.95rem;
    white-space: pre-wrap;
    overflow-y: auto;
    transition: box-shadow 0.3s ease;
}

#html-output:hover,
#preview:hover {
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

#html-output::-webkit-scrollbar,
#preview::-webkit-scrollbar {
    width: 8px;
}

#html-output::-webkit-scrollbar-thumb,
#preview::-webkit-scrollbar-thumb {
    background-color: rgba(156, 163, 175, 0.6);
    border-radius: 4px;
}

#html-output::-webkit-scrollbar-track,
#preview::-webkit-scrollbar-track {
    background: transparent;
}

@media (min-width: 768px) {
    #container {
        flex-direction: row;
        justify-content: space-between;
        gap: 20px;
    }
    .container {
        flex: 1;
        max-width: 32%;
    }
}