:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --text-color: #1f2937;
    --background-color: #f9fafb;
    --card-background: #ffffff;
    --border-color: #e5e7eb;
    --success-color: #10b981;
    --error-color: #ef4444;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
    padding: 1rem;
    max-width: 800px;
    margin: 0 auto;
}

header {
    text-align: center;
    margin-bottom: 2rem;
    padding: 1rem 0;
    border-bottom: 1px solid var(--border-color);
}

h1, h2, h3 {
    margin-bottom: 0.5rem;
}

.card {
    background-color: var(--card-background);
    border-radius: 0.5rem;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
}

.form-group {
    margin-bottom: 1rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

input, textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 0.25rem;
    font-size: 1rem;
    font-family: inherit;
}

input:focus, textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.btn {
    display: inline-block;
    padding: 0.5rem 1rem;
    font-size: 1rem;
    font-weight: 500;
    text-align: center;
    text-decoration: none;
    border: 1px solid var(--border-color);
    border-radius: 0.25rem;
    background-color: #ffffff;
    color: var(--text-color);
    cursor: pointer;
    transition: all 0.2s ease;
}

.btn.primary {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.btn:hover {
    background-color: #f9fafb;
}

.btn.primary:hover {
    background-color: var(--primary-hover);
}

.messages-container {
    margin-top: 1rem;
}

.message {
    padding: 1rem;
    border: 1px solid var(--border-color);
    border-radius: 0.25rem;
    margin-bottom: 1rem;
}

.message-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 0.5rem;
}

.message-author {
    font-weight: 600;
}

.message-timestamp {
    color: #6b7280;
    font-size: 0.875rem;
}

.empty-state {
    color: #6b7280;
    text-align: center;
    padding: 2rem 0;
}

.error {
    color: var(--error-color);
    margin-bottom: 1rem;
}

.success {
    color: var(--success-color);
    margin-bottom: 1rem;
}

footer {
    text-align: center;
    margin-top: 2rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
    color: #6b7280;
}