:root {
  --ink: #102018;
  --muted: #5d6f66;
  --line: rgba(16, 32, 24, 0.12);
  --rail: #0f2a1f;
  --rail-text: #e8f2ec;
  --accent: #1faa6e;
  --accent-2: #c8f0d8;
  --stage: #f3f7f4;
  --font: "Outfit", system-ui, sans-serif;
  --serif: "Source Serif 4", Georgia, serif;
}

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

html, body {
  height: 100%;
}

body {
  font-family: var(--font);
  color: var(--ink);
  background: var(--stage);
  overflow: hidden;
}

.shell {
  display: grid;
  grid-template-columns: 280px 1fr;
  height: 100vh;
  height: 100dvh;
}

.rail {
  position: relative;
  background:
    radial-gradient(420px 280px at 20% 0%, rgba(31, 170, 110, 0.35), transparent 60%),
    radial-gradient(360px 240px at 100% 100%, rgba(200, 240, 216, 0.18), transparent 55%),
    linear-gradient(165deg, #0c2219 0%, var(--rail) 45%, #163528 100%);
  color: var(--rail-text);
  padding: 1.35rem 1.1rem 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  overflow: hidden;
  animation: rail-in 0.55s ease both;
}

.rail::after {
  content: "";
  position: absolute;
  inset: auto -20% -30% 20%;
  height: 45%;
  background: radial-gradient(circle at 30% 30%, rgba(31, 170, 110, 0.22), transparent 65%);
  pointer-events: none;
  animation: drift 12s ease-in-out infinite alternate;
}

.rail-brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  position: relative;
  z-index: 1;
}

.rail-mark {
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 0.7rem;
  display: grid;
  place-items: center;
  font-weight: 800;
  font-size: 1.25rem;
  background: linear-gradient(145deg, var(--accent), #148a57);
  color: #fff;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.25);
}

.rail-brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.1;
}

.rail-brand-text strong {
  font-size: 1.35rem;
  font-weight: 800;
  letter-spacing: -0.03em;
}

.rail-brand-text span {
  font-family: var(--serif);
  font-size: 0.95rem;
  opacity: 0.78;
  font-weight: 500;
}

.app-nav {
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
  position: relative;
  z-index: 1;
}

.app-tab {
  text-align: left;
  border: 1px solid transparent;
  background: rgba(255, 255, 255, 0.04);
  color: inherit;
  border-radius: 12px;
  padding: 0.85rem 0.9rem;
  cursor: pointer;
  font: inherit;
  transition: background 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
}

.app-tab:hover {
  background: rgba(255, 255, 255, 0.08);
  transform: translateX(2px);
}

.app-tab.is-active {
  background: rgba(31, 170, 110, 0.22);
  border-color: rgba(200, 240, 216, 0.35);
}

.app-tab-label {
  display: block;
  font-weight: 700;
  font-size: 0.98rem;
  letter-spacing: -0.01em;
}

.app-tab-desc {
  display: block;
  margin-top: 0.2rem;
  font-size: 0.78rem;
  opacity: 0.72;
  line-height: 1.35;
}

.rail-note {
  margin-top: auto;
  font-size: 0.78rem;
  line-height: 1.45;
  opacity: 0.62;
  position: relative;
  z-index: 1;
}

.stage {
  display: flex;
  flex-direction: column;
  min-width: 0;
  min-height: 0;
  background:
    linear-gradient(180deg, #e9f2ec 0%, var(--stage) 120px, var(--stage) 100%);
  animation: stage-in 0.5s ease 0.08s both;
}

.stage-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.85rem 1.15rem;
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.55);
  backdrop-filter: blur(8px);
}

.stage-title {
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.open-new {
  font-size: 0.82rem;
  font-weight: 600;
  color: #0f6b45;
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.15s ease;
}

.open-new:hover {
  border-bottom-color: currentColor;
}

.frame-wrap {
  flex: 1;
  min-height: 0;
  padding: 0;
}

.app-frame {
  width: 100%;
  height: 100%;
  border: 0;
  display: block;
  background: #fff;
}

@keyframes rail-in {
  from { opacity: 0; transform: translateX(-12px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes stage-in {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes drift {
  from { transform: translateY(0) scale(1); }
  to { transform: translateY(-18px) scale(1.05); }
}

@media (max-width: 860px) {
  body { overflow: auto; }

  .shell {
    grid-template-columns: 1fr;
    grid-template-rows: auto 1fr;
    height: auto;
    min-height: 100vh;
    min-height: 100dvh;
  }

  .rail {
    padding: 1rem;
    gap: 1rem;
  }

  .app-nav {
    flex-direction: row;
  }

  .app-tab {
    flex: 1;
  }

  .rail-note { display: none; }

  .frame-wrap {
    min-height: calc(100dvh - 180px);
  }

  .app-frame {
    min-height: calc(100dvh - 180px);
  }
}