:root {
    --bg-color: #0f172a;
    --text-color: #f8fafc;
    --card-bg: #1e293b;
    --card-hover: #334155;
    --accent-color: #60a5fa;
    --accent-glow: rgba(96, 165, 250, 0.4);
    --warning-bg: rgba(234, 179, 8, 0.1);
    --warning-text: #fde047;
    --warning-border: rgba(234, 179, 8, 0.2);
    --transition-speed: 0.4s;
}

[data-theme="light"] {
    --bg-color: #f8fafc;
    --text-color: #0f172a;
    --card-bg: #ffffff;
    --card-hover: #f1f5f9;
    --accent-color: #3b82f6;
    --accent-glow: rgba(59, 130, 246, 0.3);
    --warning-bg: rgba(202, 138, 4, 0.1);
    --warning-text: #b45309;
    --warning-border: rgba(202, 138, 4, 0.2);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color var(--transition-speed) ease, color var(--transition-speed) ease;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    overflow-x: hidden;
    position: relative;
}

/* Background gradient effect */
body::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at center, var(--accent-glow) 0%, transparent 50%);
    opacity: 0.15;
    z-index: -1;
    pointer-events: none;
}

/* Theme Switcher */
.theme-switch-wrapper {
    position: absolute;
    top: 2rem;
    right: 2rem;
    display: flex;
    align-items: center;
    z-index: 100;
}

.theme-switch {
    display: inline-block;
    height: 34px;
    position: relative;
    width: 60px;
}

.theme-switch input {
    display: none;
}

.slider {
    background-color: #334155;
    bottom: 0;
    cursor: pointer;
    left: 0;
    position: absolute;
    right: 0;
    top: 0;
    transition: .4s;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 6px;
    box-shadow: inset 0 2px 4px rgba(0,0,0,0.3);
}

[data-theme="light"] .slider {
    background-color: #cbd5e1;
    box-shadow: inset 0 2px 4px rgba(0,0,0,0.1);
}

.slider::before {
    background-color: #fff;
    bottom: 4px;
    content: "";
    height: 26px;
    left: 4px;
    position: absolute;
    transition: .4s cubic-bezier(0.68, -0.55, 0.265, 1.55);
    width: 26px;
    z-index: 2;
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
}

.slider.round {
    border-radius: 34px;
}

.slider.round::before {
    border-radius: 50%;
}

input:checked + .slider::before {
    transform: translateX(26px);
}

.fa-sun {
    color: #f59e0b;
    font-size: 13px;
    z-index: 1;
}

.fa-moon {
    color: #f8fafc;
    font-size: 13px;
    z-index: 1;
}

/* Main Container */
.container {
    max-width: 1200px;
    width: 100%;
    padding: 4rem 2rem;
    display: flex;
    flex-direction: column;
    align-items: center;
}

/* Title Animation */
.title {
    font-size: 4.5rem;
    font-weight: 800;
    margin-bottom: 4rem;
    text-align: center;
    letter-spacing: -1px;
}

.animated-text {
    background: linear-gradient(
        to right, 
        var(--text-color) 20%, 
        var(--accent-color) 40%, 
        var(--accent-color) 60%, 
        var(--text-color) 80%
    );
    background-size: 200% auto;
    color: transparent;
    -webkit-background-clip: text;
    background-clip: text;
    animation: shine 4s linear infinite;
    display: inline-block;
}

@keyframes shine {
    to {
        background-position: 200% center;
    }
}

/* Cards */
.cards-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2.5rem;
    width: 100%;
    margin-bottom: 5rem;
    perspective: 1000px;
}

.card-link {
    text-decoration: none;
    color: inherit;
    outline: none;
}

.card {
    background-color: transparent;
    height: 380px;
    cursor: pointer;
    border-radius: 1.5rem;
    position: relative;
}

/* Subtlety glow on hover */
.card::before {
    content: '';
    position: absolute;
    top: -2px;
    left: -2px;
    right: -2px;
    bottom: -2px;
    background: linear-gradient(45deg, transparent, var(--accent-glow), transparent);
    z-index: -1;
    border-radius: 1.6rem;
    opacity: 0;
    transition: opacity 0.5s ease;
}

.card:hover::before {
    opacity: 1;
}

.card-inner {
    position: relative;
    width: 100%;
    height: 100%;
    text-align: center;
    transition: transform 0.8s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    transform-style: preserve-3d;
    box-shadow: 0 15px 35px rgba(0,0,0,0.2);
    border-radius: 1.5rem;
}

[data-theme="light"] .card-inner {
    box-shadow: 0 15px 35px rgba(0,0,0,0.05);
}

.card:hover .card-inner, .card-link:focus .card-inner {
    transform: rotateY(180deg);
}

.card-front, .card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    border-radius: 1.5rem;
    padding: 2.5rem;
    background-color: var(--card-bg);
    border: 1px solid rgba(128, 128, 128, 0.1);
}

.card-front {
    z-index: 2;
    transition: background-color 0.3s ease;
}

.card-icon {
    font-size: 3.5rem;
    color: var(--accent-color);
    margin-bottom: 1.5rem;
    transition: transform 0.3s ease;
}

.card:hover .card-icon {
    transform: translateY(-5px);
}

.card-front h3 {
    font-size: 2.2rem;
    margin-bottom: 0.5rem;
    color: var(--text-color);
}

.card-front p {
    color: var(--accent-color);
    font-weight: 600;
    letter-spacing: 2px;
    text-transform: uppercase;
    font-size: 0.85rem;
}

.card-back {
    transform: rotateY(180deg);
    background: linear-gradient(145deg, var(--card-bg), var(--card-hover));
    border: 1px solid var(--accent-glow);
}

.card-back p {
    font-size: 1.2rem;
    line-height: 1.7;
    color: var(--text-color);
    opacity: 0.9;
}

/* Warning Message */
.warning-message {
    background-color: var(--warning-bg);
    border: 1px solid var(--warning-border);
    color: var(--warning-text);
    padding: 1.25rem 2rem;
    border-radius: 1rem;
    display: flex;
    align-items: center;
    gap: 1.2rem;
    max-width: 800px;
    width: 100%;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    transform: translateY(20px);
    opacity: 0;
    animation: fadeUp 0.8s cubic-bezier(0.16, 1, 0.3, 1) forwards 0.3s;
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
}

.warning-message i {
    font-size: 1.5rem;
    flex-shrink: 0;
}

.warning-message p {
    font-size: 0.95rem;
    line-height: 1.6;
    font-weight: 500;
}

@keyframes fadeUp {
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

/* Responsive */
@media (max-width: 768px) {
    .title {
        font-size: 3rem;
        margin-bottom: 3rem;
    }
    
    .cards-container {
        grid-template-columns: 1fr;
        max-width: 450px;
    }
    
    .theme-switch-wrapper {
        top: 1.5rem;
        right: 1.5rem;
    }
    
    .container {
        padding-top: 6rem;
    }
    
    .card {
        height: 320px;
    }
    
    .warning-message {
        flex-direction: column;
        text-align: center;
        padding: 1.5rem;
    }
}