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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
    transition: background 0.3s ease;
}

.container {
    background: white;
    border-radius: 20px;
    padding: 40px;
    max-width: 800px;
    width: 100%;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    animation: fadeIn 0.8s ease-in-out;
    transition: background 0.3s ease, box-shadow 0.3s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(-30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

h1 {
    color: #333;
    font-size: 2.5em;
    margin-bottom: 20px;
    text-align: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.description {
    color: #666;
    font-size: 1.1em;
    line-height: 1.6;
    margin-bottom: 30px;
    text-align: center;
    transition: color 0.3s ease;
}

h2 {
    color: #444;
    font-size: 1.8em;
    margin-bottom: 20px;
    margin-top: 30px;
    transition: color 0.3s ease;
}

ul {
    list-style: none;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

li {
    animation: slideIn 0.6s ease-in-out backwards;
}

li:nth-child(1) {
    animation-delay: 0.2s;
}

li:nth-child(2) {
    animation-delay: 0.4s;
}

li:nth-child(3) {
    animation-delay: 0.6s;
}

li:nth-child(4) {
    animation-delay: 0.8s;
}

li:nth-child(5) {
    animation-delay: 1s;
}

li:nth-child(6) {
    animation-delay: 1.2s;
}

li:nth-child(7) {
    animation-delay: 1.4s;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

li a {
    display: block;
    padding: 25px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    text-decoration: none;
    border-radius: 15px;
    font-size: 1.2em;
    font-weight: bold;
    text-align: center;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

li a::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.2);
    transition: left 0.5s ease;
}

li a:hover::before {
    left: 100%;
}

li a:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(102, 126, 234, 0.4);
}

.pulse {
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
}

/* Theme Toggle Button */
.theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    width: 60px;
    height: 60px;
    border-radius: 50%;
    border: none;
    background: white;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5em;
    transition: all 0.3s ease;
    z-index: 1000;
}

.theme-toggle:hover {
    transform: scale(1.1);
    box-shadow: 0 6px 30px rgba(0, 0, 0, 0.3);
}

.theme-toggle .sun-icon,
.theme-toggle .moon-icon {
    position: absolute;
    transition: opacity 0.3s ease, transform 0.3s ease;
}

.theme-toggle .moon-icon {
    opacity: 0;
    transform: rotate(180deg);
}

/* Dark Mode Styles */
body.dark-mode {
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
}

body.dark-mode .container {
    background: #0f3460;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.6);
}

body.dark-mode h1 {
    background: linear-gradient(135deg, #e94560 0%, #f39c12 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

body.dark-mode .description {
    color: #bbb;
}

body.dark-mode h2 {
    color: #e0e0e0;
}

body.dark-mode li a {
    background: linear-gradient(135deg, #e94560 0%, #f39c12 100%);
}

body.dark-mode li a:hover {
    box-shadow: 0 10px 30px rgba(233, 69, 96, 0.4);
}

body.dark-mode .theme-toggle {
    background: #0f3460;
    box-shadow: 0 4px 20px rgba(233, 69, 96, 0.3);
}

body.dark-mode .theme-toggle .sun-icon {
    opacity: 0;
    transform: rotate(-180deg);
}

body.dark-mode .theme-toggle .moon-icon {
    opacity: 1;
    transform: rotate(0deg);
}