:root {
    --bg: #0f172a;
    --panel: #1e293b;
    --panel-2: #273449;
    --accent: #6366f1;
    --accent-2: #818cf8;
    --text: #e2e8f0;
    --muted: #94a3b8;
    --ok: #22c55e;
    --bad: #ef4444;
    --radius: 12px;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
    background: radial-gradient(1200px 600px at 80% -10%, #1e293b 0%, var(--bg) 60%);
    color: var(--text);
    min-height: 100vh;
}

.topbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 18px 28px;
    border-bottom: 1px solid #1f2a3c;
    position: sticky;
    top: 0;
    background: rgba(15, 23, 42, 0.85);
    backdrop-filter: blur(8px);
    z-index: 10;
}

.brand { display: flex; align-items: center; gap: 14px; }
.brand h1 { font-size: 1.2rem; margin: 0; font-weight: 600; }
.tagline { margin: 2px 0 0; font-size: 0.82rem; color: var(--muted); }

.logo {
    background: linear-gradient(135deg, var(--accent), var(--accent-2));
    color: white;
    font-weight: 800;
    padding: 10px 12px;
    border-radius: 10px;
    letter-spacing: 1px;
}

main {
    max-width: 820px;
    margin: 0 auto;
    padding: 28px 20px 80px;
}

.card {
    background: var(--panel);
    border: 1px solid #2a3a52;
    border-radius: var(--radius);
    padding: 24px;
    margin-bottom: 20px;
}
.card h2 { margin-top: 0; margin-bottom: 4px; font-size: 1.15rem; }

.muted { color: var(--muted); font-size: 0.9rem; margin-top: 0; }
code { background: var(--panel-2); padding: 2px 6px; border-radius: 6px; font-size: 0.85rem; }

label { display: block; margin: 16px 0 6px; font-size: 0.85rem; color: var(--muted); }

input[type="text"], input[type="number"], textarea {
    width: 100%;
    background: var(--panel-2);
    border: 1px solid #324158;
    color: var(--text);
    border-radius: 8px;
    padding: 10px 12px;
    font-size: 0.95rem;
    font-family: inherit;
}
input[type="text"]:focus, input[type="number"]:focus, textarea:focus {
    outline: none;
    border-color: var(--accent-2);
    box-shadow: 0 0 0 3px rgba(129, 140, 248, 0.18);
}
textarea { resize: vertical; }

.row { display: flex; gap: 16px; }
.row > div { flex: 1; }

/* ---- Enhanced file chooser (dropzone) ---- */
.dropzone {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 8px;
    text-align: center;
    margin: 8px 0 4px;
    padding: 28px 20px;
    border: 2px dashed #3a4a63;
    border-radius: var(--radius);
    background: var(--panel-2);
    color: var(--muted);
    cursor: pointer;
    transition: border-color 0.15s ease, background 0.15s ease, transform 0.05s ease;
}
.dropzone:hover { border-color: var(--accent-2); background: #2c3a52; }
.dropzone.dragover {
    border-color: var(--accent);
    background: rgba(99, 102, 241, 0.12);
}
.dropzone.has-file { border-style: solid; border-color: var(--ok); }

.dz-icon {
    font-size: 1.8rem;
    line-height: 1;
    color: var(--accent-2);
}
.dz-text { font-size: 0.92rem; }
.dz-text strong { color: var(--text); }
.dz-file {
    font-size: 0.85rem;
    color: var(--muted);
    background: #0b1220;
    border: 1px solid #243149;
    border-radius: 999px;
    padding: 5px 14px;
    max-width: 100%;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}
.dropzone.has-file .dz-file { color: var(--text); border-color: #2f6b46; }

.btn {
    margin-top: 18px;
    background: linear-gradient(135deg, var(--accent), var(--accent-2));
    color: white;
    border: none;
    border-radius: 8px;
    padding: 11px 18px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.05s ease, filter 0.15s ease;
}
.btn:hover { filter: brightness(1.1); }
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: 0.6; cursor: not-allowed; }

.tabs {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 18px;
}
.tab {
    background: var(--panel);
    color: var(--muted);
    border: 1px solid #2a3a52;
    border-radius: 999px;
    padding: 8px 16px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: background 0.15s ease, color 0.15s ease;
}
.tab:hover { color: var(--text); }
.tab.active { background: var(--accent); color: white; border-color: var(--accent); }

.panel { display: none; }
.panel.active { display: block; }

.output {
    background: #0b1220;
    border: 1px solid #243149;
    border-radius: 8px;
    padding: 14px;
    margin-top: 16px;
    white-space: pre-wrap;
    word-break: break-word;
    font-size: 0.85rem;
    color: #cbd5e1;
    max-height: 320px;
    overflow: auto;
}
.output:empty { display: none; }

.toast {
    position: fixed;
    bottom: 24px;
    left: 50%;
    transform: translateX(-50%) translateY(20px);
    background: var(--panel-2);
    border: 1px solid #324158;
    color: var(--text);
    padding: 12px 20px;
    border-radius: 10px;
    opacity: 0;
    pointer-events: none;
    transition: all 0.25s ease;
    font-size: 0.9rem;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }
.toast.error { border-color: var(--bad); }
.toast.success { border-color: var(--ok); }