:root{
    --bg: #fafbfe;
    --panel: #ffffff;
    --muted: #6b7280;
    --fg: #0f172a;
    --border: #e6e9ef;
    --accent: #2563eb;
    --accent-hover: #1d4ed8;
    --success: #10b981;
    --error: #ef4444;
    --warning: #f59e0b;
    --radius: 10px;
    --shadow: 0 1px 3px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.07);
    --transition: all 0.2s ease;
  }
  *{box-sizing:border-box}

  .interval-timer {
    font-family:Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
    font-size:15px;
    line-height:1.5;
    color:var(--fg);
    -webkit-font-smoothing:antialiased;
    -moz-osx-font-smoothing:grayscale;
  }

  body {
    transition:background-color 0.5s ease;
  }

  .shell-main.interval-timer-page {
    margin: 0;
    padding: 0;
    border: none;
    box-shadow: none;
    border-radius: 0;
    background: transparent;
  }

  body[data-shell-active] .shell-main.interval-timer-page {
    padding: 0;
  }

  .shell-main.interval-timer-page .tool-page-header,
  .shell-main.interval-timer-page .tool-lead {
    display: none;
  }

  /* Builder UI (hidden when timer is running) */
  .interval-timer .builder-ui { min-height:0;
    transition:opacity 0.3s ease, transform 0.3s ease;
  }
  body.timer-running .builder-ui{
    opacity:0;
    pointer-events:none;
    transform:scale(0.95);
  }

  /* Timer Runner (full screen overlay) */
  .timer-runner{
    position:fixed;
    top:0;
    left:0;
    right:0;
    bottom:0;
    z-index:10000;
    display:none;
    flex-direction:column;
    align-items:center;
    justify-content:center;
    background:var(--timer-bg, #0ea5e9);
    color:#fff;
    transition:background-color 0.5s ease;
    overflow:hidden;
  }
  body.timer-running .timer-runner{
    display:flex;
  }

  .timer-content{
    text-align:center;
    padding:40px;
    max-width:800px;
    width:100%;
  }

  .timer-label{
    font-size:48px;
    font-weight:700;
    margin-bottom:20px;
    text-shadow:0 2px 10px rgba(0,0,0,0.2);
    min-height:60px;
  }
  @media (max-width:600px){
    .timer-label{font-size:36px}
  }

  .timer-countdown{
    font-size:120px;
    font-weight:700;
    font-variant-numeric:tabular-nums;
    margin:40px 0;
    text-shadow:0 4px 20px rgba(0,0,0,0.3);
    line-height:1;
  }
  @media (max-width:600px){
    .timer-countdown{font-size:80px;margin:30px 0}
  }

  .timer-progress{
    width:100%;
    height:8px;
    background:rgba(255,255,255,0.2);
    border-radius:4px;
    margin:30px 0;
    overflow:hidden;
  }
  .timer-progress-bar{
    height:100%;
    background:rgba(255,255,255,0.8);
    border-radius:4px;
    transition:width 0.1s linear;
    box-shadow:0 0 10px rgba(255,255,255,0.5);
  }

  .timer-controls{
    display:flex;
    gap:16px;
    justify-content:center;
    margin-top:40px;
    flex-wrap:wrap;
  }

  .timer-btn{
    padding:16px 32px;
    font-size:18px;
    font-weight:600;
    border:none;
    border-radius:12px;
    cursor:pointer;
    background:rgba(255,255,255,0.2);
    color:#fff;
    backdrop-filter:blur(10px);
    transition:var(--transition);
    min-width:120px;
    border:2px solid rgba(255,255,255,0.3);
  }
  .timer-btn:hover{
    background:rgba(255,255,255,0.3);
    transform:translateY(-2px);
    box-shadow:0 4px 12px rgba(0,0,0,0.2);
  }
  .timer-btn:active{
    transform:translateY(0);
  }
  .timer-btn.stop{
    background:rgba(239,68,68,0.8);
    border-color:rgba(255,255,255,0.5);
  }
  .timer-btn.stop:hover{
    background:rgba(239,68,68,1);
  }

  .timer-info{
    margin-top:30px;
    font-size:16px;
    opacity:0.9;
    display:flex;
    gap:20px;
    justify-content:center;
    flex-wrap:wrap;
  }
  .timer-info-item{
    padding:8px 16px;
    background:rgba(255,255,255,0.1);
    border-radius:8px;
    backdrop-filter:blur(5px);
  }

  /* Builder styles */
  .wrap{
    max-width:1000px;
    margin:0 auto;
    padding:16px;
  }

  .interval-timer header {
    display:flex;
    align-items:center;
    gap:12px;
    justify-content:space-between;
    margin-bottom:16px;
    flex-wrap:wrap;
  }
  .interval-timer h1 {
    font-size:20px;
    margin:0;
    font-weight:700;
  }
  .subtitle{
    font-size:13px;
    color:var(--muted);
    margin-top:4px;
  }

  .toolbar{
    display:flex;
    gap:8px;
    flex-wrap:wrap;
    margin:16px 0;
    padding:12px;
    background:var(--panel);
    border:1px solid var(--border);
    border-radius:var(--radius);
    box-shadow:var(--shadow);
  }
  .btn{
    background:transparent;
    border:1px solid var(--border);
    padding:8px 12px;
    border-radius:8px;
    cursor:pointer;
    font-weight:600;
    font-size:14px;
    transition:var(--transition);
    white-space:nowrap;
  }
  .btn:hover:not([disabled]){
    background:var(--bg);
    border-color:var(--accent);
    transform:translateY(-1px);
    box-shadow:var(--shadow);
  }
  .btn.primary{
    background:var(--accent);
    color:#fff;
    border-color:transparent;
  }
  .btn.primary:hover:not([disabled]){
    background:var(--accent-hover);
    transform:translateY(-1px);
    box-shadow:var(--shadow-md);
  }
  .btn.run{
    background:var(--success);
    color:#fff;
    border-color:transparent;
    font-size:16px;
    padding:10px 20px;
  }
  .btn.run:hover:not([disabled]){
    background:#059669;
  }
  .btn.ghost{
    background:transparent;
    border-color:transparent;
  }
  .btn:active:not([disabled]){
    transform:translateY(0);
  }
  .btn[disabled]{
    opacity:.5;
    cursor:not-allowed;
    transform:none;
  }
  .btn-group{
    display:flex;
    gap:6px;
    align-items:center;
  }
  .btn-group::before{
    content:'';
    width:1px;
    height:20px;
    background:var(--border);
    margin:0 4px;
  }

  .card{
    background:var(--panel);
    border:1px solid var(--border);
    border-radius:var(--radius);
    overflow:hidden;
    box-shadow:var(--shadow);
    transition:var(--transition);
  }
  .card:hover{
    box-shadow:var(--shadow-md);
  }
  .card .hd{
    padding:12px 16px;
    border-bottom:1px solid var(--border);
    display:flex;
    align-items:center;
    justify-content:space-between;
    background:linear-gradient(180deg, #fafbfe, #ffffff);
  }
  .card .bd{
    padding:16px;
  }

  .steps{
    display:flex;
    flex-direction:column;
    gap:12px;
  }
  .step{
    border-radius:10px;
    border:1px solid var(--border);
    overflow:hidden;
    background:linear-gradient(180deg,#fff,#fbfdff);
    transition:var(--transition);
    animation:slideIn 0.2s ease;
  }
  @keyframes slideIn{
    from{opacity:0;transform:translateY(-4px)}
    to{opacity:1;transform:translateY(0)}
  }
  .step:hover{
    border-color:var(--accent);
    box-shadow:var(--shadow);
  }
  .step-row{
    display:flex;
    align-items:center;
    gap:10px;
    padding:12px;
    background:linear-gradient(180deg, rgba(37,99,235,0.03), transparent);
  }
  .kind{
    font-weight:700;
    font-size:13px;
    text-transform:uppercase;
    letter-spacing:0.5px;
  }
  .dot{
    width:18px;
    height:18px;
    border-radius:5px;
    border:2px solid rgba(0,0,0,0.1);
    flex-shrink:0;
    box-shadow:0 1px 2px rgba(0,0,0,0.1);
  }
  .actions{
    margin-left:auto;
    display:flex;
    gap:6px;
  }
  .mini{
    padding:6px 10px;
    border-radius:6px;
    font-size:12px;
    min-width:32px;
  }

  .controls{
    display:grid;
    grid-template-columns:1fr 100px 50px;
    gap:10px;
    align-items:start;
    padding:12px;
  }
  .controls input[type="text"],
  .controls input[type="number"]{
    width:100%;
    padding:8px 10px;
    border:1px solid var(--border);
    border-radius:8px;
    font:inherit;
    transition:var(--transition);
  }
  .controls input:focus{
    outline:none;
    border-color:var(--accent);
    box-shadow:0 0 0 3px rgba(37,99,235,0.1);
  }
  .controls input:invalid{
    border-color:var(--error);
  }
  .controls small{
    color:var(--muted);
    display:block;
    font-size:12px;
    margin-top:4px;
  }
  .controls input[type="color"]{
    width:100%;
    height:38px;
    border:1px solid var(--border);
    border-radius:8px;
    cursor:pointer;
    padding:2px;
  }

  .loop-children{
    padding:12px;
    border-top:2px dashed var(--border);
    display:flex;
    flex-direction:column;
    gap:10px;
    background:linear-gradient(180deg, #f8fafc, #ffffff);
  }
  .add-inline{
    display:flex;
    gap:8px;
    flex-wrap:wrap;
  }

  .status{
    font-size:13px;
    color:var(--muted);
    padding:4px 8px;
    border-radius:6px;
    background:var(--bg);
    transition:var(--transition);
  }
  .status.success{
    color:var(--success);
    background:rgba(16,185,129,0.1);
  }
  .status.error{
    color:var(--error);
    background:rgba(239,68,68,0.1);
  }

  .empty-state{
    text-align:center;
    padding:40px 20px;
    color:var(--muted);
  }
  .empty-state p{
    margin:8px 0;
  }

  .validation-error{
    color:var(--error);
    font-size:12px;
    margin-top:4px;
    display:none;
  }
  .step.invalid .validation-error{
    display:block;
  }
  .step.invalid{
    border-color:var(--error);
  }

    @media (max-width:420px){
    .controls{grid-template-columns:1fr 85px 45px}
    .toolbar{gap:6px}
    .btn{font-size:13px;padding:6px 10px}
    .interval-timer header{flex-direction:column;align-items:flex-start}
  }

  .btn:focus-visible,
  input:focus-visible{
    outline:2px solid var(--accent);
    outline-offset:2px;
  }

  /* JSON export button (minimal) */
  .json-export{
    position:fixed;
    bottom:16px;
    right:16px;
    z-index:100;
    opacity:0.7;
    transition:var(--transition);
  }
  .json-export:hover{
    opacity:1;
  }