*::before,
*::after {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: 'Poppins', sans-serif;
    background: linear-gradient(135deg, #eef2ff, #e0f2fe);
    color: #1e293b;
}

.header {
    background: linear-gradient(90deg, #2563eb, #4f46e5);
    padding: 18px 30px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
}

.header nav {
    display: flex;
    gap: 25px;
}

.header a {
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: 0.3s;
}

.header a:hover {
    opacity: 0.8;
}

.container {
    max-width: 900px;
    margin: 40px auto;
    padding: 20px;
}

h1 {
    margin-bottom: 10px;
    font-weight: 700;
}

.task-list {
    display: flex;
    flex-direction: column;
    gap: 20px;
    margin: 25px 0;
}

.task-card {
    background: white;
    padding: 20px;
    border-radius: 16px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.08);
    transition: 0.3s;
}

.task-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.12);
}

.task-card.completed h3 {
    text-decoration: line-through;
    opacity: 0.6;
}

.priority-high {
    color: #dc2626;
    font-weight: 600;
}

.priority-medium {
    color: #f59e0b;
    font-weight: 600;
}

.priority-low {
    color: #16a34a;
    font-weight: 600;
}

.btn {
    padding: 10px 16px;
    border-radius: 10px;
    border: none;
    cursor: pointer;
    font-weight: 500;
    text-decoration: none;
    display: inline-block;
    transition: 0.3s;
}

.primary {
    background: #2563eb;
    color: white;
}

.primary:hover {
    background: #1d4ed8;
    transform: scale(1.05);
}

.secondary {
    background: #94a3b8;
    color: white;
}

.secondary:hover {
    background: #64748b;
}

.danger {
    background: #dc2626;
    color: white;
}

.danger:hover {
    background: #b91c1c;
}

form {
    background: white;
    padding: 25px;
    border-radius: 16px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.08);
    display: flex;
    flex-direction: column;
    gap: 15px;
}

input,
select {
    padding: 10px;
    border-radius: 8px;
    border: 1px solid #cbd5e1;
    font-family: inherit;
}

input:focus,
select:focus {
    outline: none;
    border-color: #2563eb;
    box-shadow: 0 0 0 2px rgba(37,99,235,0.2);
}

.stats-box {
    background: white;
    padding: 25px;
    border-radius: 16px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.08);
    margin-top: 20px;
}

@media (max-width: 600px) {
    .header nav {
        flex-direction: column;
        gap: 10px;
    }

    .task-card {
        flex-direction: column;
        align-items: flex-start;
    }

    .container {
        margin: 20px;
    }
}