:root {
    --page-bg: radial-gradient(circle at 20% -10%, #1f3b8a, #05010e 65%);
    --shell-bg: rgba(7, 11, 22, 0.85);
    --panel-bg: rgba(12, 20, 38, 0.8);
    --border-color: rgba(148, 163, 184, 0.4);
    --text-color: #e2e8f0;
    --muted-color: #94a3b8;
    --accent-color: #38bdf8;
    --accent-glow: rgba(56, 189, 248, 0.35);
    --shadow-color: rgba(1, 5, 16, 0.65);
    --canvas-bg: #0b1121;
    --diagram-surface: rgba(4, 8, 18, 0.85);
    --diagram-border: rgba(148, 163, 184, 0.4);
}

[data-diagram-theme="light"] {
    --diagram-surface: #ffffff;
    --diagram-border: rgba(15, 23, 42, 0.18);
    --canvas-bg: #ffffff;
}

body {
    font-family: "Space Grotesk", "Segoe UI", system-ui, -apple-system, sans-serif;
    margin: 0;
    min-height: 100vh;
    background: var(--page-bg);
    color: var(--text-color);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: clamp(2rem, 5vw, 4rem) 1.5rem;
}

.app-shell {
    width: min(1100px, 95vw);
    background: var(--shell-bg);
    border: 1px solid rgba(148, 163, 184, 0.25);
    border-radius: 28px;
    padding: clamp(2rem, 4vw, 3rem);
    box-shadow: 0 35px 80px var(--shadow-color);
    backdrop-filter: blur(14px);
}

.hero {
    text-align: center;
    margin-bottom: 2.5rem;
}

.hero h1 {
    margin: 0;
    font-size: clamp(2rem, 4vw, 3.4rem);
    letter-spacing: -0.02em;
}

.hero p {
    margin: 1rem auto 0;
    max-width: 580px;
    color: var(--muted-color);
    font-size: 1.1rem;
}

.panel {
    background: var(--panel-bg);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    padding: 1.5rem;
    box-shadow: 0 20px 45px var(--shadow-color);
}

.panel + .panel {
    margin-top: 1.5rem;
}

.options-heading {
    margin: 1.5rem 0 0.75rem;
    font-size: 1.1rem;
    font-weight: 600;
}

.controls-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
}

.control-item {
    flex: 1 1 220px;
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
    color: var(--muted-color);
    font-size: 0.95rem;
}

.control-item label {
    font-weight: 600;
    color: var(--text-color);
    font-size: 0.95rem;
}

.control-item .checkbox-label {
    font-weight: 600;
    color: var(--text-color);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.control-item input[type="checkbox"] {
    accent-color: var(--accent-color);
}

input[type="number"],
select,
button,
input[type="text"] {
    font: inherit;
}

input[type="number"],
select {
    background: rgba(8, 13, 26, 0.8);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 0.5rem 0.9rem;
    color: var(--text-color);
}

.file-input-helper {
    text-align: center;
    margin-bottom: 1.5rem;
}

.picker-buttons {
    display: inline-flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 0.75rem;
}

.primary-btn,
.ghost-btn {
    border: 1px solid transparent;
    border-radius: 999px;
    padding: 0.85rem 1.7rem;
    font-weight: 600;
    letter-spacing: 0.01em;
    cursor: pointer;
    transition: transform 150ms ease, box-shadow 150ms ease, border-color 150ms ease;
    display: inline-flex;
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
}

.primary-btn {
    background: linear-gradient(120deg, #38bdf8, #0ea5e9);
    color: #05192b;
    box-shadow: 0 10px 25px rgba(14, 165, 233, 0.4);
}

.ghost-btn {
    background: transparent;
    border-color: rgba(226, 232, 240, 0.4);
    color: var(--text-color);
}

.primary-btn:disabled,
.ghost-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    box-shadow: none;
}

.primary-btn:not(:disabled):hover,
.ghost-btn:not(:disabled):hover {
    transform: translateY(-2px);
    box-shadow: 0 15px 30px rgba(2, 6, 23, 0.5);
}

.status-line {
    text-align: center;
    color: var(--muted-color);
    font-style: italic;
    margin-bottom: 1.5rem;
}

.diagram-wrapper {
    background: var(--diagram-surface);
    border: 1px solid var(--diagram-border);
    border-radius: 20px;
    padding: 1.25rem;
    overflow: auto;
}

.diagram-wrapper pre {
    margin: 0;
}

.panel-heading {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    align-items: flex-start;
    margin-bottom: 1rem;
}

.panel-heading h2 {
    margin: 0;
}

.download-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.sections-stack {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.section-card {
    background: var(--panel-bg);
    border: 1px solid var(--border-color);
    border-radius: 18px;
    padding: 1.25rem;
}

.section-card h3 {
    margin: 0 0 1rem;
}

.section-subtitle {
    margin: -0.5rem 0 1rem;
    color: var(--muted-color);
    font-size: 0.95rem;
}

.section-card table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.95rem;
    margin-top: 1rem;
}

.section-card th,
.section-card td {
    border: 1px solid rgba(148, 163, 184, 0.3);
    padding: 0.45rem 0.5rem;
    text-align: left;
}

.legend-block {
    margin-top: 2rem;
    color: var(--muted-color);
}

footer {
    margin-top: 2.5rem;
    text-align: center;
    color: rgba(226, 232, 240, 0.7);
    font-size: 0.95rem;
}

footer a {
    color: var(--accent-color);
    text-decoration: none;
}

.hidden {
    display: none !important;
}