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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 800px;
    margin: 0 auto;
}

.screen {
    display: block;
}

.screen.hidden {
    display: none;
}

/* Login Screen */
.login-card {
    background: white;
    border-radius: 12px;
    padding: 40px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
    max-width: 400px;
    margin: 100px auto;
}

.login-card h1 {
    text-align: center;
    color: #333;
    margin-bottom: 30px;
}

/* Main App Screen */
header {
    background: white;
    border-radius: 12px;
    padding: 20px 30px;
    margin-bottom: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

header h1 {
    color: #333;
}

/* Forms */
.todo-form {
    background: white;
    border-radius: 12px;
    padding: 30px;
    margin-bottom: 20px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.todo-form h2,
.todos-section h2 {
    color: #333;
    margin-bottom: 20px;
    font-size: 1.5em;
}

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

.form-group label {
    display: block;
    margin-bottom: 8px;
    color: #555;
    font-weight: 500;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 12px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 16px;
    font-family: inherit;
    transition: border-color 0.3s;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: #667eea;
}

.form-group textarea {
    resize: vertical;
}

/* Buttons */
.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
}

.btn-primary {
    background: #667eea;
    color: white;
}

.btn-primary:hover {
    background: #5568d3;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
    background: #6c757d;
    color: white;
}

.btn-secondary:hover {
    background: #5a6268;
}

.btn-danger {
    background: #dc3545;
    color: white;
    padding: 8px 16px;
    font-size: 14px;
}

.btn-danger:hover {
    background: #c82333;
}

.btn-success {
    background: #28a745;
    color: white;
    padding: 8px 16px;
    font-size: 14px;
    margin-right: 8px;
}

.btn-success:hover {
    background: #218838;
}

/* Todos List */
.todos-section {
    background: white;
    border-radius: 12px;
    padding: 30px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.todos-list {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.todo-item {
    background: #f8f9fa;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    padding: 20px;
    transition: all 0.3s;
}

.todo-item:hover {
    border-color: #667eea;
    box-shadow: 0 2px 8px rgba(102, 126, 234, 0.2);
}

.todo-item.completed {
    opacity: 0.7;
    background: #e8f5e9;
}

.todo-item.completed .todo-title {
    text-decoration: line-through;
    color: #6c757d;
}

.todo-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 10px;
}

.todo-title {
    font-size: 1.2em;
    font-weight: 600;
    color: #333;
    flex: 1;
}

.todo-description {
    color: #666;
    margin-bottom: 15px;
    line-height: 1.5;
}

.todo-actions {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.todo-meta {
    font-size: 0.85em;
    color: #999;
    margin-top: 10px;
}

.loading,
.error-message {
    text-align: center;
    padding: 20px;
    color: #666;
}

.error-message {
    color: #dc3545;
    margin-top: 10px;
    font-size: 14px;
}

.empty-state {
    text-align: center;
    padding: 40px;
    color: #999;
}

.empty-state h3 {
    margin-bottom: 10px;
    color: #666;
}

/* Checkbox */
.todo-checkbox {
    width: 20px;
    height: 20px;
    margin-right: 10px;
    cursor: pointer;
}