:root {
    --bg-color: #fcfcfc;
    --card-bg: #ffffff;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --accent: #111827;
    /* Near black for minimalist feel */
    --border: #e5e7eb;
    --danger: #ef4444;
    --success: #10b981;
    --font-family: 'Inter', system-ui, -apple-system, sans-serif;
    --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
}

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.5;
    display: flex;
    justify-content: center;
    padding-top: 5rem;
    min-height: 100vh;
}

.container {
    width: 100%;
    max-width: 500px;
    padding: 0 1.5rem;
}

header {
    margin-bottom: 2.5rem;
    text-align: center;
}

h1 {
    font-size: 1.5rem;
    font-weight: 600;
    letter-spacing: -0.025em;
    color: var(--accent);
}

.input-group {
    margin-bottom: 2rem;
}

form.add-task-form {
    display: flex;
    gap: 0.75rem;
}

input[type="text"] {
    flex: 1;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border);
    border-radius: 0.5rem;
    font-size: 0.95rem;
    outline: none;
    transition: border-color 0.2s, box-shadow 0.2s;
    background: var(--card-bg);
}

input[type="text"]:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(17, 24, 39, 0.05);
    /* Minimalist ring */
}

button {
    cursor: pointer;
    border: none;
    background: var(--accent);
    color: white;
    padding: 0.75rem 1.25rem;
    border-radius: 0.5rem;
    font-weight: 500;
    font-size: 0.9rem;
    transition: opacity 0.2s;
}

button:hover {
    opacity: 0.9;
}

ul {
    list-style: none;
}

.task-item {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 0.5rem;
    padding: 1rem;
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    transition: transform 0.1s ease, box-shadow 0.1s ease;
}

.task-item:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow);
    border-color: #d1d5db;
}

.task-content {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    flex: 1;
}

.task-text {
    font-size: 0.95rem;
}

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

.actions {
    display: flex;
    gap: 0.5rem;
}

.btn-icon {
    background: transparent;
    color: var(--text-secondary);
    padding: 0.25rem;
    border-radius: 0.25rem;
    font-size: 1.1rem;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border: none;
    cursor: pointer;
}

.btn-icon:hover {
    background: #f3f4f6;
    color: var(--text-primary);
}

.btn-delete:hover {
    color: var(--danger);
    background: #fef2f2;
}

/* Custom Checkbox */
.toggle-form button {
    background: transparent;
    border: 1px solid var(--border);
    width: 1.25rem;
    height: 1.25rem;
    border-radius: 0.25rem;
    padding: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    color: transparent;
}

.task-item.completed .toggle-form button {
    background: var(--accent);
    border-color: var(--accent);
    color: white;
}