:root {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --danger: #ef4444;
    --danger-hover: #dc2626;
    --text: #1f2937;
    --text-light: #6b7280;
    --bg: #f9fafb;
    --card-bg: #ffffff;
    --border: #e5e7eb;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --transition: all 0.2s ease-in-out;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
}

body {
    background-color: var(--bg);
    color: var(--text);
    min-height: 100vh;
    padding: 2rem;
    line-height: 1.5;
}

.container {
    max-width: 600px;
    margin: 2rem auto;
    background: var(--card-bg);
    padding: 2.5rem;
    border-radius: 1rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
}

h1 {
    color: var(--text);
    text-align: center;
    margin-bottom: 2rem;
    font-size: 2.25rem;
    font-weight: 700;
    background: linear-gradient(90deg, #6366f1, #8b5cf6);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.input-container {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
    position: relative;
}

.input-row {
    display: flex;
    gap: 0.75rem;
    width: 100%;
}

.task-input {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 2px solid var(--border);
    border-radius: 0.5rem;
    font-size: 1rem;
    transition: var(--transition);
    background: var(--card-bg);
    color: var(--text);
}

.datetime-container {
    display: flex;
    gap: 0.5rem;
    width: 100%;
}

.date-input,
.time-input {
    flex: 1;
    padding: 0.75rem;
    border: 2px solid var(--border);
    border-radius: 0.5rem;
    font-size: 0.9rem;
    background: var(--card-bg);
    color: var(--text);
    transition: var(--transition);
}

.date-input:focus,
.time-input:focus,
.task-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

/* Hide the default calendar icon in date input */
input[type="date"]::-webkit-calendar-picker-indicator {
    filter: invert(0.5);
    cursor: pointer;
}

input[type="time"]::-webkit-calendar-picker-indicator {
    filter: invert(0.5);
    cursor: pointer;
}

/* Dark mode adjustments */
@media (prefers-color-scheme: dark) {
    input[type="date"],
    input[type="time"] {
        color-scheme: dark;
    }
}

input[type="text"] {
    flex: 1;
    padding: 0.75rem 1rem;
    border: 2px solid var(--border);
    border-radius: 0.5rem;
    font-size: 1rem;
    transition: var(--transition);
    background: var(--card-bg);
    color: var(--text);
}

input[type="text"]:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

input[type="text"]::placeholder {
    color: var(--text-light);
    opacity: 0.7;
}

button, .add-btn {
    padding: 0.75rem 1.5rem;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    white-space: nowrap;
}

button:hover {
    background-color: var(--primary-hover);
    transform: translateY(-1px);
}

button:active {
    transform: translateY(0);
}

ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

li {
    background: var(--card-bg);
    margin: 0.5rem 0;
    padding: 1rem 1.25rem;
    border-radius: 0.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    transition: var(--transition);
    border: 1px solid var(--border);
    box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
}

.task-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
}

.task-meta {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.85rem;
    color: var(--text-light);
    margin-top: 0.25rem;
}

.task-due {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

.task-due svg {
    width: 14px;
    height: 14px;
    opacity: 0.7;
}

.task-overdue {
    color: #ef4444;
    font-weight: 500;
}

.task-today {
    color: #3b82f6;
    font-weight: 500;
}

li:hover {
    transform: translateX(4px);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
}

li span {
    flex: 1;
    position: relative;
    padding-left: 1.75rem;
    cursor: pointer;
}

li span::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 1.25rem;
    height: 1.25rem;
    border: 2px solid var(--border);
    border-radius: 0.375rem;
    transition: var(--transition);
}

li span.completed {
    color: var(--text-light);
    text-decoration: line-through;
}

li span.completed::before {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='3' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='20 6 9 17 4 12'%3E%3C/polyline%3E%3C/svg%3E");
    background-position: center;
    background-repeat: no-repeat;
    background-size: 0.75rem;
}

.delete-btn {
    background-color: var(--danger);
    color: white;
    padding: 0.4rem 0.8rem;
    font-size: 0.875rem;
    border-radius: 0.375rem;
    margin-left: 0.75rem;
    opacity: 0;
    transform: translateX(10px);
    transition: var(--transition);
}

li:hover .delete-btn {
    opacity: 1;
    transform: translateX(0);
}

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

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    :root {
        --text: #f3f4f6;
        --text-light: #9ca3af;
        --bg: #111827;
        --card-bg: #1f2937;
        --border: #374151;
    }
    
    body {
        background-color: var(--bg);
    }
    
    .container {
        box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.2), 0 2px 4px -1px rgba(0, 0, 0, 0.1);
    }
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

li {
    animation: fadeIn 0.3s ease-out forwards;
}

/* Responsive design */
@media (max-width: 640px) {
    body {
        padding: 1rem;
    }
    
    .container {
        padding: 1.5rem;
    }
    
    .input-container {
        flex-direction: column;
    }
    
    button {
        width: 100%;
        padding: 0.875rem;
    }
    
    .delete-btn {
        opacity: 1;
        transform: translateX(0);
    }
}