:root {
    --bg: #0f172a;
    --panel: #111827;
    --panel-soft: #1f2937;
    --text: #e5e7eb;
    --muted: #94a3b8;
    --accent: #38bdf8;
    --accent-dark: #0ea5e9;
    --border: #334155;
    --success-bg: #052e1f;
    --success-border: #14532d;
    --success-text: #bbf7d0;
    --error-bg: #450a0a;
    --error-border: #7f1d1d;
    --error-text: #fecaca;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: Arial, Helvetica, sans-serif;
    background: linear-gradient(180deg, #020617 0%, #0f172a 100%);
    color: var(--text);
}

.page-shell {
    width: min(1100px, calc(100% - 2rem));
    margin: 0 auto;
    padding: 2rem 0 3rem;
}

.hero {
    margin-bottom: 1.5rem;
}

.eyebrow {
    margin: 0 0 0.5rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--accent);
    font-size: 0.9rem;
    font-weight: 700;
}

h1 {
    margin: 0;
    font-size: clamp(2rem, 4vw, 3rem);
}

.hero-copy {
    margin: 0.75rem 0 0;
    max-width: 60rem;
    color: var(--muted);
    line-height: 1.6;
}

.alert {
    border: 1px solid;
    border-radius: 16px;
    padding: 1rem 1.1rem;
    margin-bottom: 1rem;
    line-height: 1.5;
}

.alert.success {
    background: var(--success-bg);
    border-color: var(--success-border);
    color: var(--success-text);
}

.alert.error {
    background: var(--error-bg);
    border-color: var(--error-border);
    color: var(--error-text);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 1rem;
    margin-bottom: 1rem;
}

.stat-card,
.tool-card {
    background: rgba(17, 24, 39, 0.88);
    border: 1px solid rgba(148, 163, 184, 0.18);
    border-radius: 20px;
    box-shadow: 0 18px 40px rgba(0, 0, 0, 0.3);
    backdrop-filter: blur(10px);
}

.stat-card {
    padding: 1rem;
}

.stat-label {
    display: block;
    color: var(--muted);
    font-size: 0.9rem;
    margin-bottom: 0.4rem;
}

.stat-card strong {
    font-size: 1.3rem;
}

.tool-card {
    padding: 1.25rem;
}

.toolbar-row,
.actions,
.help-row {
    display: flex;
    flex-wrap: wrap;
    gap: 0.9rem;
    align-items: center;
}

.toolbar-row {
    justify-content: space-between;
    margin-bottom: 1rem;
}

.file-input-wrap,
.checkbox-wrap {
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
    color: var(--muted);
}

.file-input-wrap input[type="file"] {
    color: var(--text);
}

.checkbox-wrap code {
    color: var(--text);
}

.editor-label {
    display: inline-block;
    margin-bottom: 0.6rem;
    font-weight: 700;
}

textarea {
    width: 100%;
    min-height: 480px;
    resize: vertical;
    border-radius: 16px;
    border: 1px solid var(--border);
    background: #020617;
    color: var(--text);
    padding: 1rem;
    font: 500 0.95rem/1.6 Consolas, Monaco, 'Courier New', monospace;
    margin-bottom: 1rem;
}

textarea:focus,
button:focus,
input:focus {
    outline: 3px solid rgba(56, 189, 248, 0.35);
    outline-offset: 2px;
}

button {
    border: 1px solid var(--border);
    background: var(--panel-soft);
    color: var(--text);
    border-radius: 12px;
    padding: 0.8rem 1rem;
    font-size: 0.95rem;
    font-weight: 700;
    cursor: pointer;
    transition: transform 0.15s ease, background 0.15s ease, border-color 0.15s ease;
}

button:hover:not(:disabled) {
    transform: translateY(-1px);
    border-color: var(--accent);
}

button.primary {
    background: linear-gradient(180deg, var(--accent) 0%, var(--accent-dark) 100%);
    color: #082f49;
    border-color: transparent;
}

button:disabled {
    opacity: 0.55;
    cursor: not-allowed;
}

.link-button {
    background: transparent;
    border: none;
    color: var(--accent);
    padding: 0;
}

.help-row {
    justify-content: space-between;
    color: var(--muted);
}

@media (max-width: 860px) {
    .stats-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .toolbar-row,
    .actions,
    .help-row {
        align-items: flex-start;
    }
}

@media (max-width: 560px) {
    .page-shell {
        width: min(100% - 1rem, 100%);
        padding-top: 1rem;
    }

    .stats-grid {
        grid-template-columns: 1fr;
    }

    .tool-card {
        padding: 1rem;
    }

    textarea {
        min-height: 360px;
    }

    .actions button {
        width: 100%;
    }

    .help-row {
        flex-direction: column;
        align-items: flex-start;
    }
}

.top-nav { margin-bottom: 1rem; }
.back-link { display:inline-flex; align-items:center; gap:0.45rem; color: var(--muted); text-decoration:none; font-weight:700; }
.back-link:hover { color: var(--text); }