/* css/style.css - V2 */
:root {
    --primary-color: #3f51b5; /* Indigo */
    --primary-dark: #303f9f;
    --primary-light: #e8eaf6;
    --secondary-color: #6c757d; /* Gray */
    --danger-color: #d32f2f; /* Red */
    --light-bg: #f4f5f7;
    --text-color: #333;
    --border-color: #ddd;
    --card-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--light-bg);
    color: var(--text-color);
    margin: 0;
}

.container, .container-small {
    width: 90%;
    max-width: 1024px;
    background-color: #ffffff;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--card-shadow);
    margin: 2rem auto;
}
.container-small { max-width: 500px; }

h1, h2, h3 { color: var(--primary-dark); }
h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }

hr { border: 0; height: 1px; background-color: var(--border-color); margin: 2rem 0; }

/* Forms & Buttons */
.form-group { margin-bottom: 1.5rem; }
label { display: block; margin-bottom: 0.5rem; font-weight: 600; }
input[type="text"], input[type="password"], select, textarea {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    box-sizing: border-box;
    transition: all 0.3s ease;
}
input:focus, select:focus, textarea:focus { 
    border-color: var(--primary-color); 
    outline: none;
    box-shadow: 0 0 0 3px rgba(63, 81, 181, 0.2);
}
.btn {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    text-align: center;
    text-decoration: none;
    font-size: 1rem;
    font-weight: 600;
    transition: all 0.3s ease;
}
.btn:hover { background-color: var(--primary-dark); transform: translateY(-2px); }
.btn-secondary { background-color: var(--secondary-color); }
.btn-danger { background-color: var(--danger-color); }

/* Messages */
.error-message, .success-message { padding: 15px; border-radius: 8px; margin-bottom: 1rem; }
.error-message { color: #721c24; background-color: #f8d7da; border: 1px solid #f5c6cb; }
.success-message { color: #155724; background-color: #d4edda; border: 1px solid #c3e6cb; }

/* Main Navigation Header */
.main-nav { background-color: #ffffff; padding: 1rem 0; box-shadow: 0 2px 4px rgba(0,0,0,0.05); }
.main-nav .container { 
    display: flex; justify-content: space-between; align-items: center; 
    padding: 0 2rem; margin-top: 0; margin-bottom: 0;
}
.main-nav h1 { color: var(--primary-dark); margin: 0; font-size: 1.5rem; }
.main-nav a { color: var(--primary-color); text-decoration: none; font-weight: 600; }
#user-info a { margin-left: 1rem; }

/* Teacher Dashboard Cards */
.dashboard-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 1.5rem; }
.stat-card {
    background-color: var(--primary-light);
    padding: 1.5rem;
    border-radius: 12px;
    text-align: center;
}
.stat-card .stat-number { font-size: 3rem; font-weight: 700; color: var(--primary-dark); }
.stat-card .stat-label { font-size: 1rem; color: var(--primary-color); }

/* Tables */
table { width: 100%; border-collapse: collapse; margin-top: 1.5rem; }
th, td { text-align: left; padding: 12px; border-bottom: 1px solid var(--border-color); }
th { background-color: var(--primary-light); font-weight: 600; }
tbody tr:hover { background-color: #fafafa; }

/* Chat Interface (No changes needed) */
#chat-box { height: 400px; border: 1px solid #ccc; overflow-y: scroll; padding: 10px; margin-bottom: 1rem; background-color: #fafafa; border-radius: 5px; }
.chat-message { margin-bottom: 10px; }
.chat-message.user { text-align: right; }
.chat-message.ai .message-bubble { background-color: #e3f2fd; }
.chat-message.user .message-bubble { background-color: #c8e6c9; }
.message-bubble { display: inline-block; padding: 10px 15px; border-radius: 15px; max-width: 70%; text-align: left;}
.message-sender { font-size: 0.8rem; color: #666; font-weight: bold; margin: 0 5px 5px; }
#chat-form { display: flex; }
#chat-input { flex-grow: 1; margin-right: 10px; }