:root {
    --bg: #f6f7fb;
    --bg-strong: #eef2fb;
    --text: #0f172a;
    --muted: #475569;
    --border: #e2e8f0;
    --shadow: 0 20px 60px rgba(15, 23, 42, 0.08);
    --card: #ffffff;
    --accent: #2563eb;
    --accent-strong: #1d4ed8;
    --accent-soft: #e8efff;
    --danger: #dc2626;
}

body {
    margin: 0;
    font-family: "Manrope", "Segoe UI", system-ui, -apple-system, sans-serif;
    background: radial-gradient(120% 120% at 10% 20%, #ffffff 0%, #f3f6ff 45%, #eef2fb 80%);
    color: var(--text);
    line-height: 1.5;
}

.main-layout {
    min-height: 100vh;
}

.top-bar {
    display: flex;
    align-items: center;
    padding: 14px 24px;
    background: var(--card);
    border-bottom: 1px solid var(--border);
    box-shadow: 0 8px 24px rgba(15, 23, 42, 0.05);
}

.top-bar .brand {
    font-weight: 800;
    letter-spacing: 0.4px;
}

.content {
    padding: 28px 32px 40px;
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 16px;
    align-items: center;
}

h1 {
    margin: 0 0 10px;
    letter-spacing: 0.2px;
}

.controls {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
    align-items: center;
    margin-bottom: 14px;
    justify-content: center;
}

.btn {
    background: linear-gradient(135deg, var(--accent) 0%, var(--accent-strong) 100%);
    color: #ffffff;
    border: none;
    padding: 10px 14px;
    border-radius: 10px;
    font-weight: 700;
    cursor: pointer;
    transition: transform 120ms ease, box-shadow 120ms ease, filter 120ms ease;
    box-shadow: 0 12px 28px rgba(37, 99, 235, 0.22);
}

.btn:hover:not(:disabled) {
    transform: translateY(-1px);
    filter: brightness(1.02);
}

.btn:disabled {
    opacity: 0.45;
    cursor: not-allowed;
    box-shadow: none;
}

.btn.secondary {
    background: var(--accent-soft);
    color: var(--accent-strong);
    border: 1px solid var(--border);
    box-shadow: none;
}

.drop-hint {
    padding: 26px;
    border: 1px dashed var(--border);
    border-radius: 14px;
    text-align: center;
    color: var(--muted);
    background: #ffffff;
    width: min(1100px, 100%);
    margin: 0 auto;
}

.error-banner {
    margin-top: 10px;
    padding: 12px 14px;
    border-radius: 10px;
    background: #fff1f2;
    border: 1px solid #fecdd3;
    color: #b91c1c;
}

.document-shell {
    position: relative;
    margin-top: 14px;
    border-radius: 14px;
    overflow: hidden;
    box-shadow: var(--shadow);
    background: var(--card);
    border: 1px solid var(--border);
    margin-left: auto;
    margin-right: auto;
}

canvas {
    display: block;
    width: 100%;
    height: auto;
    background: #ffffff;
}

.overlay {
    position: absolute;
    border: 1px dashed var(--accent);
    border-radius: 10px;
    padding: 8px;
    background: rgba(255, 255, 255, 0.96);
    box-shadow: 0 12px 30px rgba(37, 99, 235, 0.15);
    user-select: none;
    touch-action: none;
}

.overlay.signature img {
    display: block;
    max-width: 100%;
    max-height: 100%;
}

.overlay-controls {
    position: absolute;
    top: -44px;
    right: 0;
    display: flex;
    gap: 6px;
}

.overlay-btn {
    background: #ffffff;
    color: var(--accent-strong);
    border: 1px solid var(--accent);
    border-radius: 8px;
    padding: 6px 10px;
    cursor: pointer;
    box-shadow: 0 6px 16px rgba(37, 99, 235, 0.15);
}

.overlay-input {
    border: 1px solid var(--border);
    background: #ffffff;
    color: var(--text);
    font-size: 18px;
    padding: 6px 8px;
    min-width: 180px;
    border-radius: 8px;
    outline: none;
}

.paging {
    margin-top: 14px;
    display: flex;
    gap: 10px;
    align-items: center;
    color: var(--muted);
}

.modal-backdrop {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(15, 23, 42, 0.35);
    backdrop-filter: blur(3px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
}

.modal {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 18px;
    min-width: 760px;
    box-shadow: var(--shadow);
}

.modal-row {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-top: 12px;
    color: var(--muted);
}

.modal canvas {
    background: #ffffff;
    border: 1px solid var(--border);
    border-radius: 10px;
}

.spacer {
    flex: 1;
}