:root {
    --bg: #f4f6fa;
    --bg-subtle: #ffffff;
    --bg-card: #ffffff;
    --text: #1e293b;
    --muted: #64748b;
    --accent: #0284c7;
    --accent-bright: #0ea5e9;
    --accent-magenta: #7c3aed;
    --accent-soft: rgba(2, 132, 199, 0.08);
    --border: rgba(15, 23, 42, 0.1);
    --border-bright: rgba(2, 132, 199, 0.35);
    --highlight: #0f172a;
    --shadow-sm: 0 2px 12px rgba(15, 23, 42, 0.06);
    --shadow-md: 0 8px 24px rgba(15, 23, 42, 0.08);
    --shadow-lg: 0 12px 40px rgba(15, 23, 42, 0.1);
    --card-border: 1px solid rgba(15, 23, 42, 0.08);
    --card-shadow: 0 4px 20px rgba(15, 23, 42, 0.06);
    --glow-accent: 0 0 12px rgba(2, 132, 199, 0.15);
    --role-student: #0ea5e9;
    --role-teacher: #10b981;
    --role-leader: #7c3aed;
}

body {
    min-height: 100vh;
    background: transparent;
    color: var(--text);
    display: flex;
    flex-direction: column;
    font-family: 'Inter', "PingFang SC", "Microsoft YaHei", sans-serif;
    overflow-x: hidden;
}

.deck-bg {
    position: fixed;
    inset: 0;
    z-index: 0;
    pointer-events: none;
    overflow: hidden;
    background: linear-gradient(165deg, #ffffff 0%, #eef2f7 45%, #e8eef6 100%);
}

.deck-bg__glow {
    position: absolute;
    inset: 0;
    z-index: 0;
    background:
        radial-gradient(circle at 18% 22%, rgba(2, 132, 199, 0.07) 0%, transparent 42%),
        radial-gradient(circle at 82% 78%, rgba(124, 58, 237, 0.06) 0%, transparent 42%);
    filter: blur(48px);
}

.deck-bg__grid {
    position: absolute;
    inset: -50% -50%;
    width: 200%;
    height: 200%;
    z-index: 1;
    opacity: 0.1;
    background-image:
        linear-gradient(rgba(15, 23, 42, 0.18) 1px, transparent 1px),
        linear-gradient(90deg, rgba(15, 23, 42, 0.18) 1px, transparent 1px);
    background-size: 80px 80px;
    transform: perspective(500px) rotateX(60deg);
    animation: grid-move 30s linear infinite;
}

@keyframes grid-move {
    from { transform: perspective(500px) rotateX(60deg) translateY(0); }
    to { transform: perspective(500px) rotateX(60deg) translateY(80px); }
}

.deck-bg__grid-flat {
    position: absolute;
    inset: 0;
    z-index: 2;
    background-image:
        linear-gradient(rgba(100, 116, 139, 0.22) 1px, transparent 1px),
        linear-gradient(90deg, rgba(100, 116, 139, 0.22) 1px, transparent 1px);
    background-size: 36px 36px;
    background-position: 0 0;
    pointer-events: none;
}

.fade-in-up {
    animation: fadeInUp 0.6s cubic-bezier(0.23, 1, 0.32, 1) forwards;
    opacity: 0;
    transform: translateY(30px);
}

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

.tab-active {
    background-color: var(--accent) !important;
    color: #fff !important;
    box-shadow: 0 2px 12px rgba(2, 132, 199, 0.35);
    transform: translateY(-2px);
    border-color: var(--accent) !important;
}

.flow-arrow {
    position: absolute;
    right: -18px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--border-bright);
    font-size: 1.2rem;
    z-index: 10;
    opacity: 0.5;
}

#pc-modal {
    display: none;
    position: fixed;
    inset: 0;
    background-color: rgba(15, 23, 42, 0.45);
    z-index: 100;
    backdrop-filter: blur(8px);
    align-items: center;
    justify-content: center;
    padding: 2rem;
}

#pc-modal.active {
    display: flex;
}

.modal-content {
    background: var(--bg-subtle);
    border: 1px solid rgba(15, 23, 42, 0.1);
    border-radius: 16px;
    width: 100%;
    max-width: 1200px;
    height: 80vh;
    display: flex;
    flex-direction: column;
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

header {
    border-bottom: 1px solid rgba(15, 23, 42, 0.08);
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(10px);
}

#scenario-tabs {
    background: #f1f5f9 !important;
    border: 1px solid rgba(15, 23, 42, 0.08);
}

.tab-btn {
    color: #475569 !important;
    border: 1px solid transparent;
}

.tab-btn:hover:not(.tab-active) {
    background: #ffffff !important;
    color: #0f172a !important;
    border-color: rgba(15, 23, 42, 0.06);
}

section {
    border: 1px solid var(--border) !important;
    backdrop-filter: blur(8px);
}

.menu-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 0.5rem;
}

.menu-item {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 0.65rem 0.5rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    transition: border-color 0.2s, background 0.2s, transform 0.2s;
    cursor: default;
    position: relative;
    min-height: 80px;
    justify-content: center;
}

.menu-item:hover {
    border-color: rgba(2, 132, 199, 0.25);
    background: #fafbfc;
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

.menu-item__icon {
    width: 34px;
    height: 34px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 6px;
    font-size: 1.05rem;
    border-radius: 8px;
    background: rgba(15, 23, 42, 0.04);
    border: 1px solid var(--border);
    color: var(--accent);
}

.icon-purple {
    color: #6d28d9;
    background: rgba(124, 58, 237, 0.1);
    border-color: rgba(124, 58, 237, 0.25);
}

.icon-green {
    color: #059669;
    background: rgba(16, 185, 129, 0.12);
    border-color: rgba(16, 185, 129, 0.28);
}

.icon-blue {
    color: #0284c7;
    background: rgba(14, 165, 233, 0.1);
    border-color: rgba(14, 165, 233, 0.28);
}

.menu-item:hover .menu-item__icon {
    transform: scale(1.05);
}

.menu-item__content {
    flex: none;
    width: 100%;
}

.menu-item__title {
    font-weight: 700;
    font-size: 0.85rem;
    color: var(--text);
    display: block;
    margin-bottom: 2px;
}

.menu-item__subtitle {
    font-size: 0.65rem;
    color: var(--muted);
    font-weight: 600;
    display: block;
    line-height: 1.25;
}

.no-scrollbar::-webkit-scrollbar {
    display: none;
}

.no-scrollbar {
    -ms-overflow-style: none;
    scrollbar-width: none;
}