:root {
  --bg: #f6f7f9;
  --card-bg: #ffffff;
  --border: #e3e6ea;
  --text: #1f2329;
  --muted: #6b7280;
  --primary: #2b5cd1;
  --primary-hover: #1f48a8;
  --primary-fg: #ffffff;
  --secondary-bg: #eef0f4;
  --secondary-hover: #e0e3e9;
  --success-bg: #e8f5ed;
  --success-fg: #166534;
  --error-bg: #fdecec;
  --error-fg: #9b1c1c;
  --warn-bg: #fff7e6;
  --warn-fg: #8a5300;
  --shadow: 0 1px 2px rgba(0,0,0,0.04), 0 4px 12px rgba(0,0,0,0.04);
  --radius: 8px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui,
               "Noto Sans Bengali", "Noto Sans", Arial, sans-serif;
  font-size: 15px;
  line-height: 1.5;
}

header {
  max-width: 760px;
  margin: 0 auto;
  padding: 32px 24px 8px;
}

header h1 {
  margin: 0;
  font-size: 28px;
  letter-spacing: -0.01em;
}

header .tagline {
  color: var(--muted);
  margin: 4px 0 16px;
}

main {
  max-width: 760px;
  margin: 0 auto;
  padding: 8px 24px 48px;
}

footer {
  max-width: 760px;
  margin: 0 auto;
  padding: 8px 24px 32px;
  text-align: center;
  color: var(--muted);
  font-size: 13px;
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px 24px;
  margin: 16px 0;
}

.card h2 {
  margin: 0 0 6px;
  font-size: 18px;
}

.hint {
  color: var(--muted);
  margin: 0 0 16px;
  font-size: 14px;
}

.muted { color: var(--muted); font-weight: normal; font-size: 90%; }

/* Form fields */
.field {
  display: block;
  margin: 12px 0;
}

.field > span,
.field > legend {
  display: block;
  font-weight: 500;
  margin-bottom: 4px;
}

input[type="text"],
input[type="number"],
input[type="file"] {
  width: 100%;
  padding: 8px 10px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font: inherit;
  background: white;
}

input[type="text"]:focus,
input[type="number"]:focus,
input[type="file"]:focus {
  outline: 2px solid var(--primary);
  outline-offset: -1px;
  border-color: var(--primary);
}

fieldset {
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 10px 14px 12px;
  margin: 0;
}

legend { padding: 0 6px; }

label.checkbox,
label.radio {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  margin: 6px 0;
  cursor: pointer;
}

label.checkbox input,
label.radio input { margin-top: 3px; }

/* Buttons */
button {
  font: inherit;
  padding: 9px 16px;
  border-radius: 6px;
  border: 1px solid transparent;
  cursor: pointer;
}

button.primary {
  background: var(--primary);
  color: var(--primary-fg);
  font-weight: 500;
}
button.primary:hover { background: var(--primary-hover); }
button.primary:disabled { opacity: 0.55; cursor: progress; }

button.secondary {
  background: var(--secondary-bg);
  color: var(--text);
  margin-left: 8px;
}
button.secondary:hover { background: var(--secondary-hover); }

/* Messages */
.result, .status, .error, .warn {
  border-radius: 6px;
  padding: 10px 12px;
  margin-top: 12px;
  font-size: 14px;
}
.result { background: var(--success-bg); color: var(--success-fg); }
.error  { background: var(--error-bg);   color: var(--error-fg); }
.status { background: var(--secondary-bg); }
.warn   { background: var(--warn-bg);    color: var(--warn-fg); margin: 12px 0; }

.paper-summary {
  background: var(--secondary-bg);
  padding: 10px 14px;
  border-radius: 6px;
  margin-bottom: 14px;
  font-size: 14px;
}
.paper-summary strong { font-weight: 600; }

/* Saved-papers list */
.saved-list { display: grid; gap: 8px; }
.saved-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 8px 12px;
  background: #fafbfc;
}
.saved-row .meta { font-size: 13px; color: var(--muted); }
.saved-row button { padding: 5px 10px; font-size: 13px; }
.saved-row .use   { background: var(--primary); color: white; }
.saved-row .del   { background: transparent; color: var(--error-fg); }
.saved-row .del:hover { background: var(--error-bg); }