:root {
  --tube: #dce6ee;
  --room: #c5d0db;
  --platen: #9aabba;
  --platen-ink: #5d6e7d;
  --ink: #141820;
  --graphite: #44505c;
  --sheet: #fffaf2;
  --rule: #e4d8c8;
  --stamp: #9f1239;
  --stamp-deep: #7a0e2c;
  --glass: rgba(248, 252, 255, 0.42);
  --hairline: rgba(20, 24, 32, 0.16);
  --ui: "Sora", "Noto Sans SC", sans-serif;
  --display: "Fraunces", "Noto Serif SC", serif;
  --song: "Noto Serif SC", "Songti SC", serif;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  width: 100%;
  overflow-x: hidden;
  min-height: 100%;
  background:
    radial-gradient(1200px 480px at 50% -80px, rgba(255, 255, 255, 0.55), transparent 70%),
    linear-gradient(180deg, var(--tube) 0%, var(--room) 38%, #b7c4d0 100%);
  color: var(--ink);
  font-family: var(--ui);
}

body {
  min-height: 100dvh;
  display: flex;
  justify-content: center;
}

.machine {
  width: min(1180px, calc(100% - 32px));
  margin: 0 auto;
  padding: 28px 0 48px;
}

.mast {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 22px;
}

.brand {
  font-family: var(--display);
  font-optical-sizing: auto;
  font-size: clamp(2.4rem, 5vw, 3.4rem);
  font-weight: 600;
  letter-spacing: 0.08em;
  line-height: 1;
  margin: 0;
}

.ver {
  color: var(--platen-ink);
  font-size: 0.8em;
}

.seal-btn {
  appearance: none;
  border: 1px solid var(--hairline);
  background: rgba(255, 255, 255, 0.35);
  color: var(--ink);
  font: inherit;
  padding: 8px 14px;
  cursor: pointer;
}

.seal-btn:hover,
.seal-btn:focus-visible {
  background: rgba(255, 255, 255, 0.55);
  outline: 2px solid var(--ink);
  outline-offset: 2px;
}

.bed {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 18px;
  align-items: stretch;
}

.platen,
.tray {
  min-width: 0;
}

.platen {
  position: relative;
  background: linear-gradient(160deg, #aebdc9, var(--platen) 45%, #8899a8);
  min-height: 540px;
  padding: 22px;
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.35),
    0 18px 40px rgba(20, 24, 32, 0.18);
}

.glass {
  position: relative;
  height: calc(100% - 92px);
  min-height: 380px;
  border: 1px solid rgba(255, 255, 255, 0.35);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.28), rgba(255, 255, 255, 0.08)),
    var(--glass);
  backdrop-filter: blur(6px);
  overflow: auto;
  cursor: pointer;
}

.glass.is-hot {
  outline: 2px dashed var(--stamp);
}

.marks span {
  position: absolute;
  width: 18px;
  height: 18px;
  border: 2px solid rgba(20, 24, 32, 0.45);
  pointer-events: none;
  z-index: 2;
}

.marks .tl { top: 10px; left: 10px; border-right: 0; border-bottom: 0; }
.marks .tr { top: 10px; right: 10px; border-left: 0; border-bottom: 0; }
.marks .bl { bottom: 10px; left: 10px; border-right: 0; border-top: 0; }
.marks .br { bottom: 10px; right: 10px; border-left: 0; border-top: 0; }

.hint {
  position: absolute;
  inset: 0;
  display: grid;
  place-content: center;
  text-align: center;
  color: var(--platen-ink);
  padding: 24px;
  pointer-events: none;
}

.hint strong {
  display: block;
  color: var(--ink);
  font-weight: 600;
  margin-bottom: 6px;
}

.thumbs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding: 28px 16px 16px;
}

.thumbs img {
  width: 120px;
  height: 88px;
  object-fit: cover;
  border: 1px solid rgba(20, 24, 32, 0.25);
  background: #fff;
}

.platen-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-top: 16px;
}

.meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.meta input {
  width: 120px;
  border: 0;
  border-bottom: 1px solid rgba(20, 24, 32, 0.35);
  background: transparent;
  color: var(--ink);
  font: inherit;
  padding: 6px 2px;
}

.meta input::placeholder {
  color: rgba(20, 24, 32, 0.45);
}

.start {
  width: 86px;
  height: 86px;
  border-radius: 50%;
  border: 0;
  background: radial-gradient(circle at 35% 30%, #c91b48, var(--stamp) 46%, var(--stamp-deep));
  color: #fff8f4;
  font-family: var(--song);
  font-size: 1.15rem;
  letter-spacing: 0.12em;
  cursor: pointer;
  box-shadow: 0 8px 0 var(--stamp-deep), 0 12px 20px rgba(127, 15, 46, 0.28);
}

.start:active {
  transform: translateY(4px);
  box-shadow: 0 4px 0 var(--stamp-deep);
}

.start:disabled {
  opacity: 0.55;
  cursor: wait;
}

.start:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 3px;
}

.tray {
  background: #6f7c89;
  padding: 16px;
  min-height: 540px;
  box-shadow: 0 18px 40px rgba(20, 24, 32, 0.18);
}

.tray-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: #e8eef3;
  font-size: 0.86rem;
  margin-bottom: 10px;
}

.tray-actions {
  display: flex;
  gap: 8px;
}

.tray-actions button {
  appearance: none;
  border: 1px solid rgba(255, 255, 255, 0.3);
  background: transparent;
  color: #e8eef3;
  font: inherit;
  font-size: 0.86rem;
  padding: 5px 10px;
  cursor: pointer;
}

.tray-actions button:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.paper-well {
  background: #4e5965;
  padding: 12px;
  height: calc(100% - 36px);
  overflow: hidden;
}

.sheet-frame {
  position: relative;
  width: 100%;
  min-height: 420px;
  overflow: hidden;
}

.sheet {
  position: absolute;
  top: 0;
  left: 0;
  width: 210mm;
  min-height: 297mm;
  background: var(--sheet);
  color: var(--ink);
  font-family: var(--song);
  padding: 18mm 18mm 16mm;
  transform-origin: top left;
  box-shadow: 0 1px 0 rgba(20, 24, 32, 0.12);
}

.sheet-head {
  display: flex;
  justify-content: space-between;
  border-bottom: 1px solid var(--ink);
  padding-bottom: 6px;
  font-size: 12px;
}

.sheet-title {
  text-align: center;
  font-size: 22px;
  font-weight: 700;
  margin: 18px 0 16px;
  letter-spacing: 0.12em;
}

.who {
  text-align: center;
  font-size: 14px;
  margin: -8px 0 18px;
}

.problem {
  margin: 0 0 18px;
  font-size: 14.5px;
  line-height: 1.75;
}

.stem-no {
  font-weight: 700;
  margin-right: 0.5em;
}

.label {
  font-weight: 700;
  margin: 12px 0 8px;
}

.math {
  margin: 12px 0;
  overflow-x: auto;
  text-align: center;
}

.rowops {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 10px 14px;
  margin: 16px 0;
}

.ops {
  display: flex;
  flex-direction: column;
  align-items: center;
  font-size: 12px;
}

.ops .line {
  border-bottom: 1px solid var(--ink);
  padding: 0 8px 2px;
  min-width: 72px;
  text-align: center;
}

.arrow {
  margin-top: -2px;
}

.sheet-foot {
  margin-top: 28px;
  border-top: 1px solid var(--ink);
  padding-top: 6px;
  text-align: right;
  font-size: 12px;
}

.empty-sheet {
  min-height: 260mm;
  display: grid;
  place-content: center;
  color: #8a8073;
  text-align: center;
}

.dialog {
  border: 0;
  padding: 0;
  width: min(420px, calc(100% - 32px));
  background: var(--sheet);
  color: var(--ink);
  box-shadow: 0 24px 60px rgba(20, 24, 32, 0.28);
}

.dialog::backdrop {
  background: rgba(20, 24, 32, 0.45);
}

.dialog-body {
  padding: 22px 22px 18px;
}

.dialog h2 {
  font-family: var(--display);
  font-size: 1.6rem;
  margin: 0 0 8px;
}

.dialog p,
.dialog label {
  font-size: 0.92rem;
  color: var(--graphite);
}

.dialog a {
  color: var(--stamp);
}

.dialog label {
  display: block;
  margin: 12px 0 4px;
}

.dialog input,
.dialog select {
  width: 100%;
  font: inherit;
  padding: 8px 10px;
  border: 1px solid var(--rule);
  background: #fff;
}

.dialog menu {
  display: flex;
  justify-content: flex-end;
  gap: 8px;
  margin: 16px 0 0;
  padding: 0;
}

.dialog menu button {
  font: inherit;
  padding: 7px 12px;
  border: 1px solid var(--ink);
  background: #fff;
  cursor: pointer;
}

.dialog menu button.primary {
  background: var(--ink);
  color: #fff;
}

.status {
  margin-top: 14px;
  min-height: 1.4em;
  color: var(--graphite);
  font-size: 0.92rem;
}

.status.bad {
  color: var(--stamp-deep);
}

.hidden { display: none !important; }

@media (max-width: 1100px) {
  .bed { grid-template-columns: 1fr; }
  .paper-well { min-height: 420px; }
}

@media (prefers-reduced-motion: reduce) {
  .start { transition: none; }
}