:root {
    --primary-color: #0f766e;
    --secondary-color: #22d3ee;
    --accent-color: #a3ff12;
    --text-primary: #f8fafc;
    --text-secondary: #cbd5f5;
    --bg-primary: #050b1a;
    --bg-secondary: #0f172a;
    --bg-card: #16233d;
    --border-color: #223352;
    --shadow-light: rgba(34, 211, 238, 0.12);
    --gradient-primary: linear-gradient(140deg, #0f172a 0%, #0f766e 45%, #22d3ee 100%);
    --border-radius: 16px;
    --border-radius-small: 10px;
    --transition-fast: 0.18s ease;
}

[data-theme="light"] {
    --text-primary: #0f172a;
    --text-secondary: #1f2937;
    --bg-primary: #f1f5f9;
    --bg-secondary: #e2e8f0;
    --bg-card: #f8fafc;
    --border-color: #cbd5e1;
    --shadow-light: rgba(15, 118, 110, 0.08);
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
    font-family: 'Inter', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    transition: background-color var(--transition-fast);
    min-height: 100vh;
}

.top-nav {
    background: var(--bg-card);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 100;
    gap: 1rem;
}

.app-title {
    font-size: 1.5rem;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    flex: 1;
    text-align: center;
}

.nav-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.6rem 1rem;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-small);
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
    flex-shrink: 0;
}

.nav-btn:hover {
    background: var(--gradient-primary);
    color: white;
    transform: translateY(-2px);
}

.nav-btn .icon { font-size: 1.25rem; }

.main-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 3rem 2rem;
}

.intro-section {
    text-align: center;
    margin-bottom: 3rem;
}

.intro-section h2 {
    font-size: 2rem;
    color: var(--secondary-color);
    margin-bottom: 1rem;
}

.intro-section p {
    font-size: 1.1rem;
    color: var(--text-secondary);
}

.tasks-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

.task-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 2rem;
    text-decoration: none;
    color: var(--text-primary);
    transition: all var(--transition-fast);
    display: flex;
    flex-direction: column;
    gap: 1rem;
    position: relative;
    overflow: hidden;
}

.task-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--gradient-primary);
    transform: scaleX(0);
    transition: transform var(--transition-fast);
}

.task-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 30px var(--shadow-light);
    border-color: var(--secondary-color);
}

.task-card:hover::before {
    transform: scaleX(1);
}

.task-icon {
    font-size: 3rem;
    text-align: center;
}

.task-card h3 {
    font-size: 1.5rem;
    color: var(--secondary-color);
    margin: 0;
}

.task-card p {
    color: var(--text-secondary);
    font-size: 1rem;
    line-height: 1.6;
    flex: 1;
}

.task-points {
    display: inline-block;
    padding: 0.5rem 1rem;
    background: var(--gradient-primary);
    color: white;
    border-radius: var(--border-radius-small);
    font-weight: 600;
    font-size: 0.9rem;
    align-self: flex-start;
}

@media (max-width: 768px) {
    .top-nav { padding: 0.75rem 1rem; }
    .app-title { font-size: 1.25rem; }
    .nav-btn span:not(.icon) { display: none; }
    .main-content { padding: 2rem 1rem; }
    .intro-section h2 { font-size: 1.5rem; }
    .tasks-grid { grid-template-columns: 1fr; gap: 1.5rem; }
    .task-card { padding: 1.5rem; }
}