:root {
    --bg: #0f172a;
    --card: #1e293b;
    --text: #e2e8f0;
    --muted: #94a3b8;
    --accent: #38bdf8;
    --accent-hover: #0ea5e9;
    --radius: 12px;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.5;
    padding: 1.5rem;
}

.container {
    max-width: 720px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 0.5rem;
}

h1 {
    font-size: 1.5rem;
    font-weight: 700;
}

.clock {
    font-variant-numeric: tabular-nums;
    color: var(--accent);
    font-weight: 600;
    font-size: 1.1rem;
}

.card {
    background: var(--card);
    border-radius: var(--radius);
    padding: 1.25rem;
    border: 1px solid rgba(255,255,255,0.06);
}

.card h2 {
    font-size: 1.1rem;
    margin-bottom: 0.9rem;
    color: var(--text);
}

.counter-display {
    font-size: 3rem;
    font-weight: 800;
    color: var(--accent);
    margin-bottom: 0.75rem;
}

.btn {
    background: var(--accent);
    color: #0f172a;
    border: none;
    padding: 0.55rem 1rem;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s, transform 0.1s;
}

.btn:hover {
    background: var(--accent-hover);
}

.btn:active {
    transform: translateY(1px);
}

.todo-input-group {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 0.75rem;
}

#todo-input {
    flex: 1;
    background: #0f172a;
    color: var(--text);
    border: 1px solid rgba(255,255,255,0.1);
    padding: 0.55rem 0.75rem;
    border-radius: 8px;
    outline: none;
}

#todo-input:focus {
    border-color: var(--accent);
}

.todo-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
}

.todo-list li {
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: #0f172a;
    padding: 0.6rem 0.75rem;
    border-radius: 8px;
    border: 1px solid rgba(255,255,255,0.05);
}

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

.todo-text {
    cursor: pointer;
    user-select: none;
}

.todo-delete {
    background: transparent;
    border: none;
    color: #f87171;
    cursor: pointer;
    font-size: 0.9rem;
    padding: 0.2rem 0.4rem;
}

.todo-delete:hover {
    color: #ef4444;
}