* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root,
body {
  --bg: #0a0a0a;
  --shell: #000;
  --face-top-1: #232323;
  --face-top-2: #1d1d1d;
  --face-bot-1: #131313;
  --face-bot-2: #0c0c0c;
  --seam: #000;
  --bot-edge: #262626;
  --digit: #f0e0c0;
  --shadow: 0 8px 24px rgba(0, 0, 0, 0.5);
  --text: #f0e0c0;
  --muted: #6a6a6a;
  --muted-2: #9a9a9a;
  --err: #d76a6a;
  --form-bg: #121212;
  --form-border: #2a2a2a;
  --form-placeholder: #4a4a4a;
  --btn-bg: #f0e0c0;
  --btn-fg: #1a1a1a;
  --btn-bg-hover: #ffffff;
  --at: #6a6a6a;
  --letter-spacing: -0.02em;
}

body[data-theme='paper'] {
  --bg: #2e2e2e;
  --shell: #c8c8c8;
  --face-top-1: #ffffff;
  --face-top-2: #f6f6f0;
  --face-bot-1: #ececea;
  --face-bot-2: #dadad6;
  --seam: #b0b0b0;
  --bot-edge: #c8c8c4;
  --digit: #0a0a0a;
  --shadow: 0 8px 24px rgba(0, 0, 0, 0.45);
  --text: #f0f0e8;
  --muted: #8a8a8a;
  --muted-2: #c0c0c0;
  --form-bg: #1a1a1a;
  --form-border: #444;
  --form-placeholder: #5a5a5a;
  --btn-bg: #ffffff;
  --btn-fg: #1a1a1a;
  --btn-bg-hover: #e8e8e0;
  --at: #8a8a8a;
}

body[data-theme='solari'] {
  --bg: #050a14;
  --shell: #000;
  --face-top-1: #14365b;
  --face-top-2: #0e2a48;
  --face-bot-1: #0a1f37;
  --face-bot-2: #061425;
  --seam: #000;
  --bot-edge: #1a4070;
  --digit: #f4c34a;
  --shadow: 0 8px 24px rgba(0, 0, 0, 0.6);
  --text: #f4c34a;
  --muted: #6a7a8a;
  --muted-2: #aab4c4;
  --form-bg: #0a1525;
  --form-border: #1a3050;
  --form-placeholder: #3a5070;
  --btn-bg: #f4c34a;
  --btn-fg: #0a1525;
  --btn-bg-hover: #ffd970;
  --at: #6a7a8a;
}

body[data-theme='mint'] {
  --bg: #c4dccd;
  --shell: #aac6b6;
  --face-top-1: #fbfaf5;
  --face-top-2: #f3f0e8;
  --face-bot-1: #e8e4d8;
  --face-bot-2: #d6d2c5;
  --seam: #b8b0a8;
  --bot-edge: #d4ccc0;
  --digit: #1a4a3a;
  --shadow: 0 8px 20px rgba(20, 50, 40, 0.2);
  --text: #1a4a3a;
  --muted: #5a7a6a;
  --muted-2: #3a5a4a;
  --err: #a04040;
  --form-bg: #e8f0e8;
  --form-border: #88a898;
  --form-placeholder: #98b8a8;
  --btn-bg: #1a4a3a;
  --btn-fg: #f3f0e8;
  --btn-bg-hover: #2a5a4a;
  --at: #5a7a6a;
}

body[data-theme='vegas'] {
  --bg: #160606;
  --shell: #000;
  --face-top-1: #5a1c1c;
  --face-top-2: #461616;
  --face-bot-1: #2c0a0a;
  --face-bot-2: #1a0606;
  --seam: #000;
  --bot-edge: #5a1c1c;
  --digit: #ffd966;
  --shadow: 0 8px 24px rgba(0, 0, 0, 0.7);
  --text: #ffd966;
  --muted: #7a5a3a;
  --muted-2: #b89a72;
  --form-bg: #1a0808;
  --form-border: #4a2020;
  --form-placeholder: #5a3030;
  --btn-bg: #ffd966;
  --btn-fg: #160606;
  --btn-bg-hover: #ffe48a;
  --at: #7a5a3a;
}

body[data-theme='phosphor'] {
  --bg: #030503;
  --shell: #000;
  --face-top-1: #0e1410;
  --face-top-2: #080d0a;
  --face-bot-1: #060a08;
  --face-bot-2: #020403;
  --seam: #000;
  --bot-edge: #1a3020;
  --digit: #00ff88;
  --shadow: 0 0 32px rgba(0, 255, 136, 0.18);
  --text: #00ff88;
  --muted: #2a5a3a;
  --muted-2: #5fa878;
  --err: #ff5577;
  --form-bg: #07120a;
  --form-border: #1a4028;
  --form-placeholder: #2a5a3a;
  --btn-bg: #00ff88;
  --btn-fg: #030503;
  --btn-bg-hover: #5cffaa;
  --at: #2a5a3a;
}

body[data-theme='sunset'] {
  --bg: #1c0a0a;
  --shell: #2a1010;
  --face-top-1: #f4a060;
  --face-top-2: #e89050;
  --face-bot-1: #d77a3a;
  --face-bot-2: #c2682a;
  --seam: #6a2010;
  --bot-edge: #b85a20;
  --digit: #2a0a0a;
  --shadow: 0 10px 28px rgba(0, 0, 0, 0.55);
  --text: #f4a060;
  --muted: #8a5a4a;
  --muted-2: #c08070;
  --form-bg: #2a1010;
  --form-border: #5a2820;
  --form-placeholder: #8a4a3a;
  --btn-bg: #f4a060;
  --btn-fg: #2a0a0a;
  --btn-bg-hover: #ffb88a;
  --at: #8a5a4a;
}

html,
body {
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: 'DM Mono', ui-monospace, SFMono-Regular, Menlo, monospace;
  -webkit-font-smoothing: antialiased;
  -webkit-text-size-adjust: 100%;
  transition: background 0.4s ease, color 0.4s ease;
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100dvh;
  padding: 24px;
}

main {
  width: 100%;
  max-width: 940px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 32px;
}

#form {
  display: flex;
  align-items: center;
  background: var(--form-bg);
  border: 1px solid var(--form-border);
  border-radius: 999px;
  padding: 4px 4px 4px 18px;
  gap: 8px;
  font-size: 16px;
  transition: background 0.4s ease, border-color 0.4s ease;
}

.at {
  color: var(--at);
  font-weight: 500;
  transition: color 0.4s ease;
}

#username {
  background: transparent;
  border: 0;
  color: var(--text);
  font: inherit;
  outline: 0;
  width: clamp(160px, 30vw, 260px);
  padding: 10px 0;
  letter-spacing: 0.02em;
  transition: color 0.4s ease;
}

#username::placeholder {
  color: var(--form-placeholder);
}

#form button {
  background: var(--btn-bg);
  color: var(--btn-fg);
  border: 0;
  border-radius: 999px;
  width: 36px;
  height: 36px;
  cursor: pointer;
  font-size: 16px;
  font-weight: 700;
  transition: background 0.15s, color 0.4s ease;
}

#form button:hover {
  background: var(--btn-bg-hover);
}

.board {
  --card-w: clamp(40px, 11.5vw, 100px);
  --card-h: calc(var(--card-w) * 1.5);
  --digit-size: calc(var(--card-w) * 1.4);
  --radius: calc(var(--card-w) * 0.1);

  display: flex;
  gap: clamp(3px, 0.7vw, 7px);
  perspective: 800px;
}

.card {
  position: relative;
  width: var(--card-w);
  height: var(--card-h);
  border-radius: var(--radius);
  background: var(--shell);
  box-shadow: var(--shadow);
  transition: background 0.4s ease, box-shadow 0.4s ease;
}

.card .half,
.card .flap-front,
.card .flap-back {
  position: absolute;
  width: 100%;
  height: 50%;
  text-align: center;
  overflow: hidden;
  font-family: 'Roboto Mono', ui-monospace, monospace;
  font-weight: 700;
  font-size: var(--digit-size);
  line-height: 1;
  color: var(--digit);
  user-select: none;
  transition: background 0.4s ease, color 0.4s ease, border-color 0.4s ease;
}

.card .half.top,
.card .flap-front {
  top: 0;
  background: linear-gradient(180deg, var(--face-top-1) 0%, var(--face-top-2) 100%);
  border-radius: var(--radius) var(--radius) 1px 1px;
  border-bottom: 1px solid var(--seam);
}

.card .half.bottom,
.card .flap-back {
  bottom: 0;
  background: linear-gradient(180deg, var(--face-bot-1) 0%, var(--face-bot-2) 100%);
  border-radius: 1px 1px var(--radius) var(--radius);
  border-top: 1px solid var(--bot-edge);
}

.card .half.top span,
.card .flap-front span {
  display: block;
  height: var(--card-h);
  line-height: var(--card-h);
  letter-spacing: var(--letter-spacing);
}

.card .half.bottom span,
.card .flap-back span {
  display: block;
  height: var(--card-h);
  line-height: var(--card-h);
  margin-top: calc(var(--card-h) / -2);
  letter-spacing: var(--letter-spacing);
}

.card .flap {
  position: absolute;
  top: 0;
  width: 100%;
  height: 50%;
  transform-origin: bottom;
  transform-style: preserve-3d;
  transition: transform 0.55s cubic-bezier(0.36, 0, 0.66, 1);
  z-index: 2;
  will-change: transform;
}

.card .flap.flipping {
  transform: rotateX(-180deg);
}

.card .flap-front,
.card .flap-back {
  position: absolute;
  inset: 0;
  height: 100%;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

.card .flap-back {
  transform: rotateX(180deg);
}

.status {
  font-size: 14px;
  color: var(--muted);
  height: 1.5em;
  text-align: center;
  letter-spacing: 0.02em;
  transition: color 0.4s ease;
}

.status.ok {
  color: var(--muted-2);
}

.status.err {
  color: var(--err);
}

.themes {
  display: flex;
  gap: 14px;
  justify-content: center;
  align-items: center;
  padding: 4px 0;
}

.theme-dot {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  border: 0;
  cursor: pointer;
  padding: 0;
  position: relative;
  background: var(--dot-card);
  outline: 2px solid transparent;
  outline-offset: 3px;
  transition: transform 0.15s ease, outline-color 0.2s ease;
}

.theme-dot::before {
  content: '';
  position: absolute;
  inset: 7px;
  border-radius: 50%;
  background: var(--dot-digit);
}

.theme-dot::after {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: 50%;
  border: 1px solid rgba(255, 255, 255, 0.08);
  pointer-events: none;
}

.theme-dot:hover {
  transform: scale(1.12);
}

.theme-dot.active {
  outline-color: var(--text);
}

@media (max-width: 480px) {
  .board {
    --card-w: clamp(34px, 12vw, 60px);
  }
  #form {
    font-size: 14px;
  }
  .themes {
    gap: 10px;
  }
}