:root {
    --primary-color: #3498db;
    --secondary-color: #2ecc71;
    --danger-color: #e74c3c;
    --dark-text: #333;
    --light-text: #f8f8f8;
    --background: #f9f9f9;
    --card-bg: #fff;
    --sender-bubble: #e1f5fe;
    --receiver-bubble: #f0f0f0;
}

/* Dark mode color variables */
[data-theme="dark"] {
    --primary-color: #4dabf7;
    --secondary-color: #40c057;
    --danger-color: #ff6b6b;
    --dark-text: #e9ecef;
    --light-text: #f8f8f8;
    --background: #212529;
    --card-bg: #343a40;
    --sender-bubble: #144a6e;
    --receiver-bubble: #495057;
}

/* Theme toggle styles */
.theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 100;
    background: var(--card-bg);
    border: 1px solid rgba(0, 0, 0, 0.1);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
    transition: all 0.3s ease;
}

.theme-toggle:hover {
    transform: scale(1.1);
}

.theme-toggle i {
    font-size: 1.2rem;
    color: var(--dark-text);
}

.theme-toggle .fa-sun {
    display: none;
}

.theme-toggle .fa-moon {
    display: block;
}

[data-theme="dark"] .theme-toggle .fa-sun {
    display: block;
}

[data-theme="dark"] .theme-toggle .fa-moon {
    display: none;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--dark-text);
    background-color: var(--background);
    max-width: 900px;
    margin: 0 auto;
    padding: 20px;
    transition: all 0.3s ease;
}

header {
    text-align: center;
    padding: 40px 0;
    border-bottom: 3px solid var(--primary-color);
}

h1 {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 20px;
}

h2 {
    font-size: 1.8rem;
    margin: 30px 0 15px;
    color: var(--primary-color);
}

h3 {
    font-size: 1.4rem;
    margin: 20px 0 10px;
}

section {
    margin: 40px 0;
    padding: 20px;
    background-color: var(--card-bg);
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

p {
    margin-bottom: 15px;
}

.highlight {
    background-color: rgba(255, 248, 225, 0.1);
    padding: 15px;
    border-left: 4px solid var(--primary-color);
    font-size: 1.2rem;
    border-radius: 4px;
    text-align: center;
}

.examples {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
}

@media (max-width: 768px) {
    .examples {
        grid-template-columns: 1fr;
    }
}

.bad-example h2 {
    color: var(--danger-color);
}

.good-example h2 {
    color: var(--secondary-color);
}

.chat {
    background-color: rgba(248, 248, 248, 0.1);
    border-radius: 8px;
    padding: 15px;
    margin: 20px 0;
    border: 1px solid rgba(224, 224, 224, 0.2);
}

.message {
    margin-bottom: 15px;
    display: flex;
    flex-direction: column;
}

.time {
    font-size: 0.8rem;
    color: #666;
    margin-bottom: 3px;
}

.sender {
    align-items: flex-end;
}

.receiver {
    align-items: flex-start;
}

.bubble {
    padding: 10px 15px;
    border-radius: 18px;
    max-width: 80%;
    word-wrap: break-word;
}

.sender .bubble {
    background-color: var(--sender-bubble);
    border: 1px solid rgba(179, 229, 252, 0.2);
}

.receiver .bubble {
    background-color: var(--receiver-bubble);
    border: 1px solid rgba(224, 224, 224, 0.2);
}

.explanation {
    margin-top: 15px;
    font-style: italic;
}

ul {
    margin-left: 20px;
    margin-bottom: 20px;
}

.example {
    background-color: rgba(240, 248, 255, 0.1);
    padding: 10px 15px;
    border-radius: 6px;
    font-style: italic;
}

footer {
    text-align: center;
    margin-top: 50px;
    padding: 20px;
    border-top: 1px solid rgba(221, 221, 221, 0.1);
    color: var(--dark-text);
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

strong {
    color: var(--primary-color);
}