:root {
    --bg-color: #0f172a;
    --card-bg: rgba(30, 41, 59, 0.7);
    --accent-primary: #3b82f6;
    --accent-secondary: #2dd4bf;
    --text-main: #f8fafc;
    --text-dim: #94a3b8;
}

body {
    background-color: var(--bg-color);
    background-image: radial-gradient(circle at top right, #1e293b, #0f172a);
    color: var(--text-main);
}

.glass {
    background: var(--card-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 20px;
}

.hidden-view {
    display: none !important;
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    color: white;
    transition: transform 0.2s cubic-bezier(0.4, 0, 0.2, 1), box-shadow 0.2s;
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 25px rgba(59, 130, 246, 0.4);
}

.time-btn,
.mode-btn,
.level-btn,
.section-btn,
.grade-btn {
    transition: all 0.2s ease;
}

.time-active,
.mode-active,
.level-active,
.section-active,
.grade-active {
    background: linear-gradient(135deg, #3b82f6, #2dd4bf) !important;
    border-color: transparent !important;
    color: #fff !important;
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.35);
}

.flip-card {
    perspective: 1600px;
}

.flip-card-inner {
    position: relative;
    width: 100%;
    min-height: 320px;
    transform-style: preserve-3d;
    transition: transform 0.6s ease;
}

.flip-card.flipped .flip-card-inner {
    transform: rotateY(180deg);
}

.flip-face {
    position: absolute;
    inset: 0;
    backface-visibility: hidden;
}

.flip-back {
    transform: rotateY(180deg);
}

.builder-token-used {
    opacity: 0.45;
    pointer-events: none;
}

.floating-enroll-btn {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background: linear-gradient(135deg, #3b82f6, #2dd4bf);
    color: white;
    padding: 14px 28px;
    border-radius: 50px;
    font-weight: 800;
    box-shadow: 0 10px 30px rgba(59, 130, 246, 0.4);
    z-index: 9999;
    transition: all 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    display: flex;
    align-items: center;
    gap: 10px;
    border: 2px solid rgba(255, 255, 255, 0.2);
}

.floating-enroll-btn:hover {
    transform: scale(1.05) translateY(-5px);
    box-shadow: 0 15px 40px rgba(59, 130, 246, 0.6);
}

@media (max-width: 640px) {
    .floating-enroll-btn {
        bottom: 20px;
        right: 20px;
        padding: 10px 20px;
        font-size: 14px;
    }
}