:root{
  --bg: #12151a;
  --panel: #1a1f27;
  --panel-border: #262c37;
  --text: #eceef1;
  --text-dim: #8b93a1;
  --accent: #5eead4;
  --accent-dim: #2c4a47;
  --warn: #ff8a5b;
  --font-ui: 'Inter', -apple-system, 'Malgun Gothic', sans-serif;
  --font-digit: 'IBM Plex Mono', monospace;
}

*{ box-sizing: border-box; }

body{
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-ui);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

header{
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 28px;
  border-bottom: 1px solid var(--panel-border);
}

header .brand{
  font-weight: 700;
  font-size: 18px;
  color: var(--text);
  text-decoration: none;
  letter-spacing: -0.01em;
}

header nav a{
  color: var(--text-dim);
  text-decoration: none;
  margin-left: 22px;
  font-size: 14px;
}

header nav a:hover, header nav a.active{ color: var(--accent); }

.lang-toggle{
  padding: 6px 14px;
  font-size: 13px;
  font-weight: 600;
  border-radius: 999px;
  border: 1px solid var(--panel-border);
  background: transparent;
  color: var(--text-dim);
  cursor: pointer;
}
.lang-toggle:hover{ color: var(--accent); border-color: var(--accent); }

.menu-toggle{
  display: none;
  background: transparent;
  border: 1px solid var(--panel-border);
  color: var(--text);
  border-radius: 8px;
  padding: 6px 10px;
  font-size: 16px;
  cursor: pointer;
  margin-right: 8px;
}

.layout{
  flex: 1;
  display: flex;
  align-items: flex-start;
  width: 100%;
}

.sidebar{
  width: 220px;
  flex-shrink: 0;
  padding: 24px 12px;
  border-right: 1px solid var(--panel-border);
  position: sticky;
  top: 0;
  max-height: 100vh;
  overflow-y: auto;
}

.sidebar details{ margin-bottom: 4px; }

.sidebar summary{
  cursor: pointer;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-dim);
  padding: 8px 8px;
  border-radius: 6px;
  list-style: none;
}
.sidebar summary::-webkit-details-marker{ display: none; }
.sidebar summary:hover{ color: var(--accent); }

.sidebar a{
  display: block;
  padding: 6px 8px 6px 18px;
  font-size: 13px;
  color: var(--text);
  text-decoration: none;
  border-radius: 6px;
}
.sidebar a:hover{ background: var(--panel); color: var(--accent); }
.sidebar a.active{ background: var(--accent-dim); color: var(--accent); font-weight: 600; }

main{
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 60px 20px;
  min-width: 0;
}

@media (max-width: 800px){
  .menu-toggle{ display: inline-block; }
  .sidebar{
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: 260px;
    background: var(--bg);
    z-index: 50;
    transform: translateX(-100%);
    transition: transform 0.2s ease;
    box-shadow: 2px 0 12px rgba(0,0,0,0.4);
  }
  .sidebar.open{ transform: translateX(0); }
  .sidebar-overlay{
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.5);
    z-index: 40;
  }
  .sidebar-overlay.open{ display: block; }
}

.panel{
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 14px;
  padding: 48px 40px;
  width: 100%;
  max-width: 520px;
  text-align: center;
}

.digit-display{
  font-family: var(--font-digit);
  font-size: 72px;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
  margin: 10px 0 28px;
}

.controls{
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

button{
  font-family: var(--font-ui);
  font-size: 15px;
  font-weight: 600;
  padding: 12px 26px;
  border-radius: 999px;
  border: 1px solid var(--panel-border);
  background: transparent;
  color: var(--text);
  cursor: pointer;
}

button.primary{
  background: var(--accent);
  border-color: var(--accent);
  color: #0a1614;
}

button.warn{
  background: var(--warn);
  border-color: var(--warn);
  color: #2a1206;
}

button:disabled{ opacity: 0.4; cursor: default; }

.field-row{
  display: flex;
  gap: 10px;
  justify-content: center;
  margin-bottom: 28px;
}

.field{
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.field label{ font-size: 12px; color: var(--text-dim); }

.field input{
  width: 72px;
  font-family: var(--font-digit);
  font-size: 22px;
  text-align: center;
  background: var(--bg);
  border: 1px solid var(--panel-border);
  border-radius: 8px;
  color: var(--text);
  padding: 8px 0;
}

.lap-list{
  margin-top: 24px;
  text-align: left;
  max-height: 220px;
  overflow-y: auto;
  font-family: var(--font-digit);
  font-size: 14px;
  color: var(--text-dim);
}

.lap-list div{
  display: flex;
  justify-content: space-between;
  padding: 6px 4px;
  border-bottom: 1px solid var(--panel-border);
}

.tool-list{
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  width: 100%;
  max-width: 800px;
}

.tool-card{
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  padding: 24px;
  text-decoration: none;
  color: var(--text);
}

.tool-card h3{ margin: 0 0 6px; font-size: 17px; }
.tool-card p{ margin: 0; font-size: 13px; color: var(--text-dim); }

.lede{
  color: var(--text-dim);
  font-size: 14px;
  max-width: 480px;
  margin: 0 0 40px;
  text-align: center;
  line-height: 1.6;
}

.faq{
  max-width: 520px;
  width: 100%;
  margin-top: 36px;
  text-align: left;
}

.faq h2{ font-size: 16px; margin-bottom: 14px; }
.faq details{
  border-top: 1px solid var(--panel-border);
  padding: 14px 0;
}
.faq summary{ cursor: pointer; font-size: 14px; color: var(--text); }
.faq p{ font-size: 13px; color: var(--text-dim); margin: 10px 0 0; line-height: 1.6; }

footer{
  text-align: center;
  padding: 24px;
  font-size: 12px;
  color: var(--text-dim);
  border-top: 1px solid var(--panel-border);
}

@media (max-width: 480px){
  .digit-display{ font-size: 48px; }
  .panel{ padding: 32px 20px; }
}