/* Base Reset and Typography */
:root {
    --primary-color: #007bff;
    --secondary-color: #6c757d;
    --success-color: #28a745;
    --danger-color: #dc3545;
    --bg-color: #f8f9fa;
    --card-bg: #ffffff;
    --border-color: #e9ecef;
    --text-color: #343a40;
    --font-family: 'Roboto', sans-serif;
}

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.site-header {
    background-color: var(--primary-color);
    color: white;
    padding: 1rem 0;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.site-header h1 {
    margin-bottom: 0.25rem;
    font-size: 1.8rem;
}

.branding {
    font-size: 0.9rem;
    margin-top: 0.5rem;
}

.branding a {
    color: #ffd700; /* Gold color for contrast */
    text-decoration: none;
    font-weight: bold;
}

.branding a:hover {
    text-decoration: underline;
}

/* Main Container (Mobile-first) */
.container {
    max-width: 90%;
    margin: 20px auto;
    padding: 15px;
    flex-grow: 1;
}

/* Input Form Styling */
.todo-input {
    margin-bottom: 30px;
    background: var(--card-bg);
    padding: 15px;
    border-radius: 8px;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

#todo-form {
    display: flex;
    gap: 10px;
}

#todo-input {
    flex-grow: 1;
    padding: 10px;
    border: 2px solid var(--border-color);
    border-radius: 4px;
    font-size: 1rem;
    transition: border-color 0.2s;
}

#todo-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.25);
}

#add-button {
    /* Ensure the button doesn't shrink too much on mobile */
    min-width: 90px;
    padding: 10px 15px;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 700;
    transition: background-color 0.2s;
}

#add-button:hover {
    background-color: #0056b3;
}

/* Todo List Styling */
.todo-list-container h2 {
    font-size: 1.5rem;
    margin-bottom: 10px;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 5px;
}

#todo-list {
    list-style: none;
    padding: 0;
}

.todo-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 15px;
    margin-bottom: 8px;
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.03);
    transition: background-color 0.3s, opacity 0.3s;
}

.todo-item .task-text {
    flex-grow: 1;
    margin-right: 15px;
    word-break: break-word;
    cursor: pointer;
}

/* Completed State */
.todo-item.completed {
    background-color: #e9ffed; /* Light green background */
    border-left: 5px solid var(--success-color);
    opacity: 0.7;
}

.todo-item.completed .task-text {
    text-decoration: line-through;
    color: var(--secondary-color);
}

/* Actions (Buttons) */
.todo-actions {
    display: flex;
    gap: 8px;
}

.todo-actions button {
    padding: 8px 12px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: opacity 0.2s;
}

.todo-actions button:hover {
    opacity: 0.8;
}

.delete-btn {
    background-color: var(--danger-color);
    color: white;
}

/* Empty State Styling */
.empty-state {
    text-align: center;
    color: var(--secondary-color);
    font-style: italic;
    border: none;
    box-shadow: none;
    padding: 20px;
}

/* Footer */
.site-footer {
    padding: 10px;
    text-align: center;
    font-size: 0.8rem;
    color: var(--secondary-color);
    border-top: 1px solid var(--border-color);
    margin-top: auto; /* Push footer to the bottom */
}

/* Responsive adjustments for larger screens */
@media (min-width: 600px) {
    .container {
        max-width: 600px;
    }
    
    .site-header h1 {
        font-size: 2.5rem;
    }

    #todo-form {
        flex-direction: row;
    }
    
    #todo-input {
        padding: 12px;
        font-size: 1.1rem;
    }

    #add-button {
        padding: 12px 20px;
    }
    
    .todo-item {
        padding: 15px 20px;
    }
}