:root {
    --bg-color: #000000;
    --glass-panel: rgba(20, 20, 20, 0.6);
    --glass-border: rgba(255, 255, 255, 0.1);
    --text-main: #ffffff;
    --text-muted: #a1a1a1;
    --accent: #ffffff;
    /* Difficulty Colors */
    --diff-easy: #00c853; /* Bright Green */
    --diff-mid: #ffd600; /* Vivid Yellow */
    --diff-hard: #ff3d00; /* Electric Red */
}

body {
    margin: 0;
    background-color: var(--bg-color);
    color: var(--text-main);
    font-family: 'Inter', sans-serif;
    height: 100vh;
    overflow: hidden;
    position: relative;
}

/* --- ANIMATED BACKGROUND (WHITE ORBS) --- */
.orb {
    position: fixed;
    border-radius: 50%;
    filter: blur(80px);
    background: rgba(255, 255, 255, 0.15);
    z-index: -1;
    animation: drift 25s infinite alternate ease-in-out;
}

.orb-1 {
    width: 400px;
    height: 400px;
    top: -100px;
    left: -100px;
}

.orb-2 {
    width: 300px;
    height: 300px;
    bottom: 10%;
    right: 10%;
    animation-delay: -5s;
}

@keyframes drift {
    from {
        transform: translate(0,0) scale(1);
    }
    to {
        transform: translate(100px, 50px) scale(1.1);
    }
}

/* --- GLASS UI --- */
.glass {
    background: var(--glass-panel);
    backdrop-filter: blur(24px);
    -webkit-backdrop-filter: blur(24px);
    border: 1px solid var(--glass-border);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.5);
}

.app-layout {
    display: flex;
    height: 100vh;
}

/* --- SIDEBAR --- */
.sidebar {
    width: 280px;
    padding: 40px 30px;
    display: flex;
    flex-direction: column;
    border-right: 1px solid var(--glass-border);
    border-radius: 0 24px 24px 0;
    margin-right: 20px;
}

.brand {
    font-size: 18px;
    font-weight: 700;
    letter-spacing: 1px;
    margin-bottom: 50px;
    display: flex;
    align-items: center;
    gap: 10px;
    color: white;
}

.nav-btn {
    display: flex;
    align-items: center;
    gap: 15px;
    padding: 16px 20px;
    color: var(--text-muted);
    text-decoration: none;
    border-radius: 16px;
    transition: 0.3s;
    margin-bottom: 12px;
    font-weight: 500;
}

    .nav-btn:hover, .nav-btn.active {
        background: rgba(255, 255, 255, 0.1);
        color: white;
        transform: translateX(5px);
    }

/* --- DROPDOWNS --- */
select {
    background: rgba(20, 20, 20, 0.9) !important; /* Dark background */
    color: white !important;
    border: 1px solid var(--glass-border);
    padding: 14px;
    border-radius: 12px;
    width: 100%;
    outline: none;
    cursor: pointer;
    font-size: 14px;
    appearance: none; /* Removes default OS styling */
    -webkit-appearance: none;
    background-image: url("data:image/svg+xml;charset=UTF-8,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3e%3cpolyline points='6 9 12 15 18 9'%3e%3c/polyline%3e%3c/svg%3e");
    background-repeat: no-repeat;
    background-position: right 1rem center;
    background-size: 1em;
}

    /* Force options to be dark in Chrome/Edge */
    select option {
        background-color: #000000;
        color: white;
        padding: 10px;
    }

/* --- MAIN CONTENT --- */
.main-content {
    flex: 1;
    padding: 50px;
    overflow-y: auto;
}

/* --- CARDS --- */
.card-grid {
    display: grid;
    gap: 30px;
    max-width: 1000px;
    margin: 0 auto;
}

.resource-card {
    padding: 30px;
    border-radius: 24px;
    transition: all 0.4s cubic-bezier(0.25, 0.8, 0.25, 1);
    position: relative;
    overflow: hidden;
}

    .resource-card:hover {
        transform: translateY(-8px) scale(1.01);
        border-color: rgba(255, 255, 255, 0.3);
        box-shadow: 0 20px 40px rgba(0,0,0,0.4);
    }

/* --- BADGES --- */
.badge {
    padding: 6px 14px;
    border-radius: 50px;
    font-size: 11px;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    display: inline-block;
    margin-bottom: 15px;
}

.lvl-1 {
    background: rgba(0, 200, 83, 0.15);
    color: var(--diff-easy);
    border: 1px solid var(--diff-easy);
}

.lvl-2 {
    background: rgba(255, 214, 0, 0.15);
    color: var(--diff-mid);
    border: 1px solid var(--diff-mid);
}

.lvl-3 {
    background: rgba(255, 61, 0, 0.15);
    color: var(--diff-hard);
    border: 1px solid var(--diff-hard);
}

/* --- BUTTONS --- */
.btn-primary {
    background: white;
    color: black;
    border: none;
    padding: 14px 32px;
    border-radius: 50px;
    font-weight: 700;
    cursor: pointer;
    transition: 0.3s;
    box-shadow: 0 0 15px rgba(255,255,255,0.2);
}

    .btn-primary:hover {
        transform: scale(1.05);
        box-shadow: 0 0 25px rgba(255,255,255,0.4);
    }

.btn-icon {
    background: rgba(255,255,255,0.1);
    border: 1px solid rgba(255,255,255,0.2);
    color: white;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: 0.2s;
}

    .btn-icon:hover {
        background: white;
        color: black;
    }

/* --- LOGIN OVERLAY --- */
.login-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 999;
    display: flex;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(15px);
    background: rgba(0,0,0,0.6);
}

.login-box {
    width: 380px;
    padding: 50px;
    border-radius: 32px;
    text-align: center;
    border: 1px solid rgba(255,255,255,0.15);
    box-shadow: 0 20px 50px rgba(0,0,0,0.5);
}

.login-input {
    box-sizing: border-box; 
    background: rgba(0,0,0,0.3);
    border: 1px solid rgba(255,255,255,0.2);
    padding: 18px;
    border-radius: 16px;
    color: white;
    width: 100%;
    margin-bottom: 20px;
    font-size: 16px;
    text-align: center;
    outline: none;
    transition: 0.3s;
}

    .login-input:focus {
        border-color: white;
        background: rgba(0,0,0,0.5);
    }

/* Utility */
.hidden {
    display: none !important;
}

.search-container {
    display: flex;
    gap: 15px;
    margin-bottom: 50px;
    background: rgba(255,255,255,0.05);
    padding: 8px;
    border-radius: 60px;
    border: 1px solid rgba(255,255,255,0.1);
}

.search-input-main {
    flex: 1;
    background: transparent;
    border: none;
    color: white;
    padding: 0 20px;
    font-size: 16px;
    outline: none;
}