* {
  box-sizing: border-box;
}

:root {
  --bg: #f4f8fb;
  --panel: #ffffff;
  --ink: #092033;
  --muted: #4f6778;
  --line: #d6e3ed;
  --accent: #0f9fb8;
  --accent-strong: #087289;
  --accent-soft: #e6f7fa;
  --danger-bg: #ffe7ea;
  --danger-line: #ffb8c2;
  --danger-ink: #8a1f30;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: Inter, "Segoe UI", system-ui, -apple-system, sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at 10% 12%, rgba(15, 159, 184, 0.2), transparent 38%),
    radial-gradient(circle at 88% 84%, rgba(8, 114, 137, 0.16), transparent 35%),
    linear-gradient(180deg, #eef4f9 0%, #f8fbfd 100%);
}

.app-shell {
  width: min(900px, calc(100% - 2rem));
  margin: 1.2rem auto 2rem;
  display: grid;
  gap: 1rem;
}

.card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 1rem 1.1rem;
  box-shadow: 0 18px 36px rgba(14, 50, 76, 0.08);
}

.hero {
  background:
    linear-gradient(130deg, rgba(15, 159, 184, 0.14), rgba(255, 255, 255, 0.7)),
    repeating-linear-gradient(90deg, rgba(16, 146, 166, 0.07) 0 1px, transparent 1px 20px),
    var(--panel);
}

.hero h1 {
  margin: 0.35rem 0 0.5rem;
  font-size: clamp(1.5rem, 2.7vw, 2rem);
  letter-spacing: 0.02em;
}

.eyebrow {
  margin: 0;
  color: var(--accent-strong);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-size: 0.74rem;
  font-weight: 700;
}

.subtitle {
  margin: 0;
  color: var(--muted);
  line-height: 1.5;
}

h2 {
  margin: 0 0 0.8rem;
  font-size: 1.07rem;
}

.file-upload-area {
  border: 2px dashed #9ec7d4;
  border-radius: 14px;
  padding: 1.5rem 1rem;
  text-align: center;
  cursor: pointer;
  background: linear-gradient(180deg, rgba(15, 159, 184, 0.06), rgba(255, 255, 255, 0.85));
  transition: border-color 0.2s ease, transform 0.2s ease, background-color 0.2s ease;
}

.file-upload-area:hover,
.file-upload-area.dragover,
.file-upload-area:focus-visible {
  border-color: var(--accent);
  transform: translateY(-1px);
  background: linear-gradient(180deg, rgba(15, 159, 184, 0.11), rgba(255, 255, 255, 0.95));
  outline: none;
}

.upload-hint {
  margin: 0.45rem 0 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.checkbox-group {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.75rem;
}

.checkbox-label {
  display: flex;
  gap: 0.5rem;
  align-items: center;
  color: var(--ink);
  font-size: 0.95rem;
}

.checkbox-label input[type="checkbox"] {
  accent-color: var(--accent);
  width: 16px;
  height: 16px;
}

.step-summary {
  border-left: 4px solid var(--accent);
}

.summary-row {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: 0.75rem;
  padding: 0.45rem 0;
  border-top: 1px solid #edf3f7;
}

.summary-row:first-of-type {
  border-top: none;
}

.summary-label {
  color: var(--muted);
  text-transform: uppercase;
  font-size: 0.78rem;
  letter-spacing: 0.05em;
  font-weight: 600;
}

.summary-value {
  color: #0e324b;
  font-weight: 600;
  word-break: break-word;
}

.field-label {
  display: block;
  font-size: 0.9rem;
  margin: 0 0 0.35rem;
  color: #1f3f56;
  font-weight: 600;
}

input[type="text"] {
  width: 100%;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: #ffffff;
  color: var(--ink);
  padding: 0.6rem 0.7rem;
  font-size: 0.95rem;
}

input[type="text"]:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(15, 159, 184, 0.18);
}

.sender-row {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr) auto;
  gap: 0.65rem;
  padding: 0.7rem;
  border: 1px solid #e0edf4;
  border-radius: 12px;
  background: #f8fcfe;
  align-items: center;
  margin-bottom: 0.6rem;
}

.sender-label {
  font-size: 0.9rem;
  color: #1f4156;
  word-break: break-word;
}

.sender-alias {
  width: 100%;
}

.color-picker {
  border: 1px solid #c5ddeb;
  border-radius: 10px;
  background: #fff;
  color: #13394e;
  font-weight: 600;
  font-size: 0.82rem;
  padding: 0.55rem 0.8rem;
  cursor: pointer;
  min-width: 92px;
}

.action-card {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.7rem;
}

.btn {
  border: none;
  border-radius: 10px;
  padding: 0.72rem 0.95rem;
  font-weight: 700;
  font-size: 0.89rem;
  cursor: pointer;
  text-align: center;
  text-decoration: none;
}

.btn:disabled {
  opacity: 0.62;
  cursor: not-allowed;
}

.btn-primary {
  background: linear-gradient(145deg, var(--accent), var(--accent-strong));
  color: #ffffff;
}

.btn-secondary {
  background: #dceaf3;
  color: #153549;
}

.btn-small {
  padding: 0.5rem 0.8rem;
  font-weight: 600;
  font-size: 0.8rem;
}

.download-card {
  border: 1px solid #b8dce6;
  background: linear-gradient(180deg, rgba(15, 159, 184, 0.08), #ffffff 58%);
}

.download-header {
  display: grid;
  gap: 0.2rem;
  margin-bottom: 0.75rem;
}

.download-title {
  font-size: 1rem;
  font-weight: 800;
  color: #10425a;
}

.download-subtitle {
  color: var(--muted);
  font-size: 0.88rem;
}

.btn-download {
  display: inline-block;
  width: 100%;
  background: linear-gradient(145deg, #0f9fb8, #0b7f96);
  color: #ffffff;
}

.loading,
.status-card {
  display: flex;
  flex-direction: column;
  gap: 0.7rem;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 1rem;
}

.loading[hidden],
.status-card[hidden],
#downloadSection[hidden],
#optionsSection[hidden],
#errorCard[hidden] {
  display: none !important;
}

.spinner {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  border: 4px solid #e0edf4;
  border-top-color: var(--accent);
  animation: spin 0.9s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

.error-card {
  display: flex;
  justify-content: space-between;
  gap: 0.8rem;
  align-items: center;
  border-color: var(--danger-line);
  background: var(--danger-bg);
  color: var(--danger-ink);
}

@media (max-width: 760px) {
  .checkbox-group {
    grid-template-columns: 1fr;
  }

  .action-card {
    grid-template-columns: 1fr;
  }

  .sender-row {
    grid-template-columns: 1fr;
  }

  .summary-row {
    grid-template-columns: 98px 1fr;
  }
}