:root {
    --primary: #4A90E2;
    --background: #f8f9fa;
    --surface: #ffffff;
    --text: #333333;
    --text-light: #666666;
    --border: #e0e0e0;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: var(--background);
    color: var(--text);
    line-height: 1.6;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 20px;
}

header {
    background-color: var(--surface);
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
    padding: 20px 0;
    margin-bottom: 40px;
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

h1 {
    color: var(--primary);
    font-size: 24px;
}

nav a {
    text-decoration: none;
    color: var(--text-light);
    margin-left: 20px;
    font-weight: 500;
}

nav a.active, nav a:hover {
    color: var(--primary);
}

.intro {
    text-align: center;
    margin-bottom: 40px;
}

.intro h2 {
    margin-bottom: 10px;
}

.intro p {
    color: var(--text-light);
    max-width: 600px;
    margin: 0 auto;
}

/* Translator UI */
.translator-ui {
    display: flex;
    gap: 20px;
}

.box {
    flex: 1;
    display: flex;
    flex-direction: column;
}

.box label {
    font-weight: bold;
    margin-bottom: 8px;
    color: var(--primary);
}

.box textarea {
    height: 300px;
    padding: 15px;
    border: 1px solid var(--border);
    border-radius: 8px;
    resize: none;
    font-size: 16px;
    transition: border-color 0.2s;
}

.box textarea:focus {
    outline: none;
    border-color: var(--primary);
}

#output-text {
    background-color: #f1f5f9;
}

/* Grammar Page */
.grammar-content h2 {
    margin-bottom: 15px;
}

.rule-box {
    background-color: var(--surface);
    padding: 20px;
    border-radius: 8px;
    margin-top: 20px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.03);
    border: 1px solid var(--border);
}

.rule-box h3 {
    color: var(--primary);
    margin-bottom: 10px;
}

.rule-box ul {
    margin-top: 10px;
    padding-left: 20px;
}