/* ===== RESET & BASE ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --primary-light: #dbeafe;
    --success: #16a34a;
    --success-light: #dcfce7;
    --warning: #d97706;
    --warning-light: #fef3c7;
    --danger: #dc2626;
    --danger-light: #fecaca;
    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-400: #94a3b8;
    --gray-500: #64748b;
    --gray-600: #475569;
    --gray-700: #334155;
    --gray-800: #1e293b;
    --gray-900: #0f172a;
    --radius: 8px;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background: var(--gray-50);
    min-height: 100vh;
    padding: 20px;
    color: var(--gray-800);
}

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

/* ===== HEADER ===== */
header {
    text-align: center;
    margin-bottom: 30px;
}

header h1 {
    font-size: 28px;
    font-weight: 700;
    color: var(--gray-800);
}

header .subtitle {
    color: var(--gray-500);
    font-size: 14px;
    margin-top: 4px;
}

/* ===== STATS ===== */
.stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
    margin-bottom: 24px;
}

.stat-card {
    background: white;
    padding: 14px;
    border-radius: var(--radius);
    text-align: center;
    border: 1px solid var(--gray-200);
}

.stat-label {
    display: block;
    font-size: 11px;
    color: var(--gray-500);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.3px;
}

.stat-value {
    display: block;
    font-size: 22px;
    font-weight: 700;
    color: var(--gray-800);
    margin-top: 2px;
}

/* ===== ADD TODO FORM ===== */
.add-todo-form {
    background: white;
    padding: 20px 24px;
    border-radius: var(--radius);
    border: 1px solid var(--gray-200);
    margin-bottom: 24px;
}

.add-todo-form h2 {
    font-size: 16px;
    margin-bottom: 14px;
    color: var(--gray-800);
}

.form-group {
    margin-bottom: 10px;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    font-size: 14px;
    font-family: inherit;
    transition: 0.2s;
    background: var(--gray-50);
    color: var(--gray-800);
}

.form-group input:focus,
.form-group textarea:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
    outline: none;
    background: white;
}

.form-group textarea {
    resize: vertical;
    min-height: 50px;
}

.btn-add {
    width: 100%;
    padding: 10px;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: var(--radius);
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: 0.2s;
    font-family: inherit;
}

.btn-add:hover {
    background: var(--primary-dark);
}

/* ===== TODO LIST ===== */
.todos-container {
    background: white;
    padding: 20px 24px;
    border-radius: var(--radius);
    border: 1px solid var(--gray-200);
}

.todos-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 14px;
    flex-wrap: wrap;
    gap: 10px;
}

.todos-header h2 {
    font-size: 16px;
    color: var(--gray-800);
}

.filters {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 4px 12px;
    border: 1px solid var(--gray-200);
    border-radius: 20px;
    background: white;
    cursor: pointer;
    font-size: 12px;
    font-weight: 500;
    transition: 0.2s;
    color: var(--gray-500);
    font-family: inherit;
}

.filter-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.filter-btn.active {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}

/* ===== TODO ITEMS ===== */
.todo-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.todo-item {
    padding: 14px 16px;
    border-radius: var(--radius);
    border: 1px solid var(--gray-200);
    transition: 0.2s;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
}

.todo-item:hover {
    border-color: var(--gray-300);
}

.todo-item.completed .todo-content h3 {
    text-decoration: line-through;
    color: var(--gray-400);
}

.todo-content {
    flex: 1;
}

.todo-content h3 {
    font-size: 15px;
    font-weight: 600;
    color: var(--gray-800);
    margin-bottom: 2px;
}

.todo-content p {
    font-size: 13px;
    color: var(--gray-500);
    margin-bottom: 4px;
}

.todo-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    align-items: center;
}

.status-badge {
    padding: 2px 10px;
    border-radius: 12px;
    font-size: 11px;
    font-weight: 600;
}

.status-pending {
    background: var(--warning-light);
    color: var(--warning);
}

.status-in_progress {
    background: var(--primary-light);
    color: var(--primary);
}

.status-completed {
    background: var(--success-light);
    color: var(--success);
}

.todo-actions {
    display: flex;
    gap: 4px;
    flex-shrink: 0;
}

.todo-actions button {
    padding: 4px 10px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 12px;
    font-weight: 500;
    transition: 0.2s;
    font-family: inherit;
}

.btn-status {
    background: var(--primary-light);
    color: var(--primary);
}

.btn-status:hover {
    background: #bfdbfe;
}

.btn-reopen {
    background: var(--warning-light);
    color: var(--warning);
}

.btn-reopen:hover {
    background: #fde68a;
}

.btn-edit {
    background: var(--gray-200);
    color: var(--gray-600);
}

.btn-edit:hover {
    background: var(--gray-300);
}

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

.btn-delete:hover {
    background: #fca5a5;
}

.loading {
    text-align: center;
    padding: 30px;
    color: var(--gray-400);
}

.empty {
    text-align: center;
    padding: 30px;
    color: var(--gray-400);
}

/* ===== RESPONSIVE ===== */
@media (max-width: 640px) {
    .stats {
        grid-template-columns: repeat(2, 1fr);
        gap: 8px;
    }

    .stat-card {
        padding: 10px;
    }

    .stat-value {
        font-size: 18px;
    }

    .todos-header {
        flex-direction: column;
        align-items: stretch;
    }

    .filters {
        justify-content: center;
    }

    .todo-item {
        flex-direction: column;
        align-items: stretch;
    }

    .todo-actions {
        justify-content: flex-end;
    }

    header h1 {
        font-size: 22px;
    }

    .add-todo-form {
        padding: 16px;
    }

    .todos-container {
        padding: 16px;
    }
}

@media (max-width: 400px) {
    .stats {
        grid-template-columns: 1fr 1fr;
        gap: 6px;
    }

    .stat-card {
        padding: 8px;
    }

    .stat-value {
        font-size: 16px;
    }

    .filter-btn {
        font-size: 11px;
        padding: 4px 10px;
    }

    .todo-actions button {
        font-size: 11px;
        padding: 3px 8px;
    }
}