body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
    background: #f8fafc;
    padding: 24px;
    color: #0f172a;
}

.container {
    max-width: 1200px;
    margin: auto;
    background: #ffffff;
    border-radius: 14px;
    box-shadow: 0 8px 28px rgba(0,0,0,0.06);
    overflow: hidden;
}

.header {
    background: linear-gradient(135deg, #6366f1, #22d3ee);
    padding: 36px 20px;
    text-align: center;
}

.header h1 {
    margin: 0 0 8px;
    font-size: 1.8rem;
    font-weight: 700;
    color: #ffffff;
}

.header p {
    margin: 0 auto;
    max-width: 720px;
    font-size: 1rem;
    color: #e0f2fe;
    line-height: 1.6;
}

.section-header {
    background: #f1f5f9;
    padding: 18px 22px;
    font-size: 1.15rem;
    font-weight: 700;
    border-top: 1px solid #e5e7eb;
}

.row {
    display: grid;
    grid-template-columns: 36px 1fr 160px;
    padding: 14px 22px;
    border-top: 1px solid #e5e7eb;
    align-items: center;
}

.row:hover {
    background: #f9fafb;
}

.dot {
    color: #64748b;
    font-size: 18px;
}

.problem {
    font-weight: 500;
}

/**************** Difficulty tags CSS *****************/
.tag {
    margin-left: 10px;
    padding: 2px 10px;
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 600;
}

.easy { background: #dcfce7; color: #166534; }
.medium { background: #fef3c7; color: #92400e; }
.hard { background: #fee2e2; color: #991b1b; }

/************* Solution Link CSS **********************************/
.solution a {
    text-decoration: none;
    font-weight: 600;
    color: #2563eb;
}

.na {
    color: #94a3b8;
    font-size: 0.9rem;
}

/************* Filter Bar CSS **********************************/
.filter-bar {
    padding: 12px 20px;
    border-bottom: 1px solid #e5e7eb;
    background: #ffffff;
}

.filter-bar select {
    padding: 6px 10px;
    border-radius: 6px;
    border: 1px solid #d1d5db;
}

/************* Footer CSS *************************************/
footer {
    text-align: center;
    margin-top: 30px;
}

footer a {
    text-decoration: none;
    color: #2563eb;
    font-weight: 500;
}

/************* Contact Button CSS ******************************/
.contact-btn {
position: fixed;       /* Fixed to viewport */
top: 20px;             /* Distance from top */
right: 20px;           /* Distance from right */
padding: 12px 24px;
font-size: 1rem;
background-color: #222;
color: #fff;
text-decoration: none;
border-radius: 8px;
box-shadow: 0 4px 12px rgba(0,0,0,0.2);
transition: background 0.3s ease, transform 0.2s ease;
z-index: 1000;         /* Make sure it’s above everything */
}

.contact-btn:hover {
    background-color: #444;
    transform: translateY(-2px);
}