:root {
    --primary: #007bff;
    --danger: #dc3545;
    --bg: #f0f2f5;
    --text: #1c1e21;
    --card-bg: #ffffff;
    --border: #dee2e6;
}

body { 
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; 
    margin: 0; 
    padding: 0;
    background: var(--bg); 
    color: var(--text); 
}

.top-nav {
    background: #fff;
    padding: 15px 20px;
    border-bottom: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 100;
}

.top-nav h1 { margin: 0; font-size: 1.25rem; }
.nav-link { text-decoration: none; color: var(--primary); font-weight: 600; font-size: 0.9rem; }

.container { padding: 15px; max-width: 800px; margin: 0 auto; }

.bulk-actions { 
    background: var(--card-bg); 
    padding: 15px; 
    border-radius: 12px; 
    margin-bottom: 15px; 
    display: flex; 
    align-items: center; 
    gap: 12px; 
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    position: sticky;
    top: 70px; 
    z-index: 90;
}

.btn-bulk-del { 
    background: var(--danger); 
    color: white; 
    border: none; 
    padding: 10px 16px; 
    border-radius: 8px; 
    cursor: pointer; 
    font-weight: bold;
    font-size: 0.9rem;
}

.history-list { display: flex; flex-direction: column; gap: 10px; }

.history-card {
    background: var(--card-bg);
    padding: 15px;
    border-radius: 12px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    display: grid;
    grid-template-columns: 40px 1fr auto;
    align-items: center;
    gap: 10px;
}

.history-details { display: flex; flex-direction: column; gap: 2px; }
.history-stack { font-size: 0.75rem; color: #65676b; text-transform: uppercase; font-weight: bold; }
.history-task { font-weight: 700; font-size: 1rem; }
.history-meta { font-size: 0.85rem; color: #65676b; }

.history-duration { 
    text-align: right; 
    font-family: monospace; 
    font-weight: bold; 
    color: var(--primary);
    font-size: 1rem;
}

.history-actions {
    grid-column: 1 / span 3;
    border-top: 1px solid var(--border);
    padding-top: 10px;
    margin-top: 5px;
    display: flex;
    justify-content: flex-end;
    gap: 20px;
}

.btn-edit, .btn-del { 
    background: none; 
    border: none; 
    padding: 8px; 
    font-weight: 600; 
    font-size: 0.85rem; 
    cursor: pointer; 
    text-decoration: none;
}
.btn-edit { color: var(--primary); }
.btn-del { color: var(--danger); }

@media (min-width: 600px) {
    .history-card { grid-template-columns: 40px 1fr 2fr 100px auto; }
    .history-actions { grid-column: auto; border: none; padding: 0; margin: 0; }
}

input[type="checkbox"] { transform: scale(1.3); cursor: pointer; }