:root {
    --bg: #e8f4ff;
    --card: #f7eefc;
    --accent: #b8d7f7;
    --accent-dark: #7eaed9;
    --text: #3d4462;
    --muted: #7a7f96;
    --border: #d9d2e6;
    --shadow: 0 18px 50px rgba(92, 105, 139, 0.12);
}

* {
    box-sizing: border-box;
}

html, body {
    min-height: 100%;
}

body {
    margin: 0;
    font-family: "Inter", "Poppins", sans-serif;
    background: radial-gradient(circle at top, #f5f8ff 0%, #e8f4ff 45%, #dbeafc 100%);
    color: var(--text);
}

.todo-app {
    max-width: 520px;
    margin: 4rem auto;
    padding: 2rem;
    background: linear-gradient(180deg, #ffffff 0%, #f7eefc 100%);
    border: 1px solid var(--border);
    border-radius: 32px;
    box-shadow: var(--shadow);
}

.todo-header {
    display: flex;
    flex-direction: column;
    gap: 0.6rem;
    text-align: center;
    margin-bottom: 1.6rem;
}

.todo-header h1 {
    margin: 0;
    font-size: 2.2rem;
    letter-spacing: -0.04em;
    color: #243b72;
}

.todo-header p {
    margin: 0;
    color: var(--muted);
    font-size: 0.97rem;
}

.todo-input-group {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 0.85rem;
    margin-bottom: 1.4rem;
}

.todo-input-group input[type="text"] {
    width: 100%;
    padding: 1rem 1.1rem;
    border: 1px solid var(--border);
    border-radius: 20px;
    background: #fbfbff;
    color: var(--text);
    font-size: 1rem;
    outline: none;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.todo-input-group input[type="text"]:focus {
    border-color: var(--accent-dark);
    box-shadow: 0 0 0 5px rgba(184, 215, 247, 0.18);
}

.todo-input-group button {
    padding: 1rem 1.4rem;
    border: none;
    border-radius: 20px;
    background: linear-gradient(135deg, #9fc8ff, #c8d0ff);
    color: #ffffff;
    font-weight: 700;
    cursor: pointer;
    transition: transform 0.2s ease, filter 0.2s ease;
}

.todo-input-group button:hover {
    transform: translateY(-1px);
    filter: brightness(1.05);
}

.todo-list {
    list-style: none;
    margin: 0;
    padding: 0;
    display: grid;
    gap: 0.95rem;
}

.todo-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    padding: 1rem 1.2rem;
    background: rgba(255, 255, 255, 0.95);
    border: 1px solid var(--border);
    border-radius: 22px;
    transition: transform 0.2s ease;
}

.todo-item:hover {
    transform: translateY(-1px);
}

.todo-item-left {
    display: flex;
    align-items: center;
    gap: 0.85rem;
}

.todo-item input[type="checkbox"] {
    width: 1.1rem;
    height: 1.1rem;
    accent-color: #99c4ff;
}

.todo-item label {
    font-size: 1rem;
    color: var(--text);
}

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

.todo-item button {
    background: none;
    border: none;
    color: var(--muted);
    cursor: pointer;
    font-size: 1.1rem;
    padding: 0.4rem;
}

.todo-item button:hover {
    color: var(--accent-dark);
}



.todo-footer {
    margin-top: 1.4rem;
    padding-top: 1.2rem;
    border-top: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    color: var(--muted);
    font-size: 0.95rem;
}

.todo-footer button {
    padding: 0.9rem 1.3rem;
    border: none;
    border-radius: 20px;
    background: linear-gradient(135deg, #9fc8ff, #c8d0ff);
    color: #ffffff;
    font-weight: 700;
    cursor: pointer;
    transition: transform 0.2s ease, filter 0.2s ease;
}

.todo-footer button:hover {
    transform: translateY(-1px);
    filter: brightness(1.05);
}

@media (max-width: 540px) {
    .todo-app {
        margin: 2rem 1rem;
        padding: 1.5rem;
    }
    .todo-input-group {
        grid-template-columns: 1fr;
    }
    .todo-input-group button {
        width: 100%;
    }
}