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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    color: #333;
    line-height: 1.6;
    padding: 20px;
    min-height: 100vh;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    background: white;
    border-radius: 20px;
    padding: 30px;
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.1);
}

header {
    text-align: center;
    margin-bottom: 40px;
    padding-bottom: 20px;
    border-bottom: 3px solid #4a6fa5;
}

h1 {
    color: #2c3e50;
    font-size: 2.5rem;
    margin-bottom: 10px;
}

h2 {
    color: #7f8c8d;
    font-weight: 300;
}

.task-section {
    background: #f8f9fa;
    border-radius: 15px;
    padding: 25px;
    margin-bottom: 30px;
    border-left: 5px solid #4a6fa5;
}

h3 {
    color: #2c3e50;
    margin-bottom: 15px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.task-instructions {
    background: white;
    border-radius: 10px;
    padding: 20px 20px 20px 40px;
    margin: 15px 0;
    border: 1px solid #e9ecef;
}

.task-instructions li {
    margin-bottom: 8px;
}

.demo-box {
    background: white;
    border-radius: 10px;
    padding: 20px;
    margin-top: 20px;
    border: 2px solid #e9ecef;
}

/* Кнопки */
button {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    margin: 10px 10px 10px 0;
}

button:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.btn-primary {
    background: linear-gradient(135deg, #4a6fa5, #3a5a8c);
    color: white;
}

.btn-success {
    background: linear-gradient(135deg, #2ecc71, #27ae60);
    color: white;
}

.btn-secondary {
    background: linear-gradient(135deg, #95a5a6, #7f8c8d);
    color: white;
}

/* Список дел */
#todoList {
    list-style-type: none;
    margin: 20px 0;
    padding: 0;
}

#todoList li {
    padding: 15px;
    margin-bottom: 10px;
    background: #f8f9fa;
    border-radius: 8px;
    border-left: 4px solid #4a6fa5;
    transition: all 0.3s;
}

/* Форма */
#userForm {
    background: #f8f9fa;
    padding: 20px;
    border-radius: 10px;
    margin: 20px 0;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: #2c3e50;
}

.form-group input {
    width: 100%;
    padding: 12px;
    border: 2px solid #ddd;
    border-radius: 8px;
    font-size: 16px;
    transition: border-color 0.3s;
}

.form-group input:focus {
    outline: none;
    border-color: #4a6fa5;
    box-shadow: 0 0 0 3px rgba(74, 111, 165, 0.2);
}

.error-input {
    border-color: #e74c3c !important;
    background-color: #fdf2f0;
}

.error-message {
    color: #e74c3c;
    font-size: 14px;
    margin-top: 5px;
    display: block;
}

/* Сообщения */
.message-box {
    background: linear-gradient(135deg, #e3f2fd, #bbdefb);
    border-radius: 10px;
    padding: 20px;
    margin: 20px 0;
    border-left: 5px solid #2196f3;
    display: none;
}

.message-box .highlight {
    color: #2196f3;
    font-weight: bold;
}

/* Футер */
footer {
    text-align: center;
    margin-top: 40px;
    padding-top: 20px;
    border-top: 1px solid #ddd;
    color: #7f8c8d;
    font-size: 14px;
}

/* Адаптивность */
@media (max-width: 768px) {
    .container {
        padding: 20px;
    }
    
    h1 {
        font-size: 2rem;
    }
    
    button {
        width: 100%;
        justify-content: center;
        margin: 10px 0;
    }
}