:root {
    color-scheme: light;
    --ink-strong: #0f172a;
    --ink-body: #334155;
    --ink-soft: #64748b;
    --line: #dbe4f0;
    --panel: rgba(255, 255, 255, 0.92);
    --bg-top: #f6fbff;
    --bg-bottom: #eef6ff;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: "Segoe UI", ui-sans-serif, system-ui, sans-serif;
    color: var(--ink-strong);
    background:
        radial-gradient(circle at top left, rgba(20, 184, 166, 0.12), transparent 28%),
        radial-gradient(circle at top right, rgba(59, 130, 246, 0.12), transparent 26%),
        linear-gradient(180deg, var(--bg-top) 0%, var(--bg-bottom) 100%);
}

.panel {
    background: var(--panel);
    border: 1px solid rgba(219, 228, 240, 0.9);
    box-shadow: 0 20px 45px -30px rgba(15, 23, 42, 0.35);
    backdrop-filter: blur(16px);
}

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

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

.markdown-body {
    color: var(--ink-body);
    line-height: 1.8;
}

.markdown-body h1 {
    font-size: 2.2rem;
    line-height: 1.15;
    font-weight: 800;
    color: var(--ink-strong);
    margin-bottom: 1.25rem;
    letter-spacing: -0.03em;
}

.markdown-body h2 {
    font-size: 1.7rem;
    line-height: 1.2;
    font-weight: 800;
    color: var(--ink-strong);
    margin: 0 0 1rem;
    padding-bottom: 0.85rem;
    border-bottom: 1px solid var(--line);
}

.markdown-body h3 {
    font-size: 1.15rem;
    line-height: 1.3;
    font-weight: 700;
    color: var(--ink-strong);
    margin-bottom: 0.9rem;
}

.markdown-body p,
.markdown-body li,
.markdown-body td,
.markdown-body blockquote {
    color: var(--ink-body);
}

.markdown-body p {
    margin-bottom: 1rem;
}

.markdown-body strong {
    color: var(--ink-strong);
    font-weight: 700;
}

.markdown-body ul:not(.task-list),
.markdown-body ol {
    margin: 0 0 1.25rem 1.3rem;
}

.markdown-body li {
    margin-bottom: 0.55rem;
}

.markdown-body hr {
    border: 0;
    border-top: 1px solid var(--line);
    margin: 2rem 0;
}

.markdown-body blockquote {
    margin: 1.5rem 0;
    padding: 1rem 1.15rem;
    border-left: 4px solid #38bdf8;
    background: #eff8ff;
    border-radius: 0.85rem;
}

.markdown-body table {
    width: 100%;
    border-collapse: separate;
    border-spacing: 0;
    margin: 1.35rem 0;
    overflow: hidden;
    border: 1px solid var(--line);
    border-radius: 1rem;
}

.markdown-body th {
    text-align: left;
    background: #f8fafc;
    color: var(--ink-strong);
    font-weight: 700;
    padding: 0.9rem 1rem;
    border-bottom: 1px solid var(--line);
}

.markdown-body td {
    padding: 0.9rem 1rem;
    border-bottom: 1px solid var(--line);
}

.markdown-body tr:last-child td {
    border-bottom: 0;
}

.markdown-body tr:nth-child(even) td {
    background: #fbfdff;
}

.markdown-body code:not(pre code) {
    background: #e2e8f0;
    color: #0f172a;
    padding: 0.12rem 0.38rem;
    border-radius: 0.45rem;
    font-size: 0.92em;
}

.subsection-card {
    margin: 1.6rem 0;
    padding: 1.35rem;
    border-radius: 1.25rem;
    border: 1px solid transparent;
}

.subsection-step {
    background: linear-gradient(180deg, #f8fbff 0%, #ffffff 100%);
    border-color: #d7e8ff;
}

.subsection-challenge {
    background: linear-gradient(180deg, #f2fffa 0%, #ffffff 100%);
    border-color: #bbf7d0;
}

.subsection-question {
    background: linear-gradient(180deg, #fffaf1 0%, #ffffff 100%);
    border-color: #fde68a;
}

.subsection-general {
    background: linear-gradient(180deg, #fafcff 0%, #ffffff 100%);
    border-color: #e2e8f0;
}

.table-shell {
    overflow-x: auto;
    margin: 1.5rem 0;
    border-radius: 1rem;
}

@media print {
    body {
        background: #ffffff;
    }

    header,
    footer,
    #student-panel,
    #usage-panel,
    #progress-panel {
        display: none !important;
    }

    .panel,
    .subsection-card {
        box-shadow: none !important;
        backdrop-filter: none !important;
        background: #ffffff !important;
    }
}