:root{
  --bg:#0A0A0A;
  --sidebar:#0D0D0D;
  --surface:#161616;
  --surface-2:#1E1E1E;
  --border:#242424;
  --text:#F2F2F2;
  --text-muted:#8F8F8F;
  --text-faint:#5C5C5C;
  --blue:#5B8DEF;
  --purple:#A78BFA;
  --teal:#4FA8A0;
  --red:#E05656;
  --green:#5BD98A;
  --amber:#E8C15A;
}
*{box-sizing:border-box;margin:0;padding:0;}
html,body{height:100%;}
body{
  background:var(--bg);
  color:var(--text);
  font-family:'Inter',sans-serif;
  -webkit-font-smoothing:antialiased;
}

.app-shell{display:flex;height:100vh;width:100%;overflow:hidden;}

/* ===== sidebar ===== */
.sidebar{
  width:250px;flex-shrink:0;
  background:var(--sidebar);
  border-right:1px solid var(--border);
  display:flex;flex-direction:column;
  height:100vh;
  padding:14px 10px;
}
.side-brand{display:flex;align-items:center;gap:8px;padding:6px 8px 16px;}
.mark{
  width:22px;height:22px;border-radius:6px;
  background:var(--surface-2);border:1px solid var(--border);
  display:flex;align-items:center;justify-content:center;
  font-weight:700;font-size:12px;flex-shrink:0;
}
.side-brand span{font-size:14px;font-weight:600;}

button.new-chat{
  display:flex;align-items:center;gap:8px;
  background:var(--surface);border:1px solid var(--border);
  border-radius:8px;padding:9px 10px;font-size:13px;color:var(--text);
  cursor:pointer;margin-bottom:16px;width:100%;font-family:inherit;
}
button.new-chat:hover{background:var(--surface-2);}

.side-label{
  font-size:11px;color:var(--text-faint);text-transform:uppercase;letter-spacing:0.5px;
  padding:10px 10px 6px;
}
.side-item{
  display:flex;align-items:center;gap:10px;
  padding:8px 10px;border-radius:7px;font-size:13.5px;color:var(--text-muted);
  cursor:pointer;position:relative;
}
.side-item:hover{background:var(--surface);color:var(--text);}
.side-item.active{background:var(--surface);color:var(--text);}
.side-item .icn{width:16px;height:16px;flex-shrink:0;display:flex;align-items:center;justify-content:center;}
.side-item .icn.blue{color:var(--blue);}
.side-item .icn.purple{color:var(--purple);}
.side-item .icn.teal{color:var(--teal);}
.side-item .icn.grey{color:var(--text-faint);}
.key-dot{width:7px;height:7px;border-radius:50%;margin-left:auto;flex-shrink:0;}
.key-dot.ok{background:var(--teal);}
.key-dot.missing{background:#E05656;}

.side-chats{flex:1;overflow-y:auto;margin-top:4px;}
.chat-item{
  display:flex;align-items:center;justify-content:space-between;gap:6px;
  padding:7px 10px;border-radius:7px;font-size:13px;color:var(--text-muted);
  cursor:pointer;
}
.chat-item:hover{background:var(--surface);color:var(--text);}
.chat-item.active{background:var(--surface);color:var(--text);}
.chat-item-title{overflow:hidden;text-overflow:ellipsis;white-space:nowrap;flex:1;}
.chat-item-delete{
  background:none;border:none;color:var(--text-faint);font-size:11px;cursor:pointer;
  opacity:0;transition:opacity .12s ease;padding:2px 4px;flex-shrink:0;
}
.chat-item:hover .chat-item-delete{opacity:1;}
.chat-item-delete:hover{color:var(--text);}

.side-footer{border-top:1px solid var(--border);padding-top:10px;margin-top:8px;}

/* mobile drawer */
.sidebar-backdrop{display:none;}
.mobile-topbar{display:none;}
@media (max-width:860px){
  .sidebar-backdrop{
    display:block;position:fixed;inset:0;background:rgba(0,0,0,0.6);
    opacity:0;pointer-events:none;transition:opacity .15s ease;z-index:20;
  }
  .sidebar-backdrop.show{opacity:1;pointer-events:auto;}
  .sidebar{
    position:fixed;left:0;top:0;bottom:0;z-index:30;
    transform:translateX(-100%);transition:transform .18s ease;
  }
  .sidebar.open{transform:translateX(0);}
  .mobile-topbar{
    display:flex;align-items:center;gap:12px;
    padding:14px 18px;border-bottom:1px solid var(--border);flex-shrink:0;
  }
  .study-pick-grid{grid-template-columns:1fr !important;}
}
.hamburger-btn{background:none;border:none;color:var(--text);font-size:18px;cursor:pointer;}
.brand-name-mobile{font-size:14px;font-weight:600;}

/* ===== main ===== */
.main{
  flex:1;height:100vh;overflow-y:auto;
  display:flex;flex-direction:column;align-items:center;
}
.footer-note{text-align:center;font-size:11px;color:var(--text-faint);padding:14px 24px 22px;}

/* ===== welcome / empty state ===== */
.center-block{
  width:100%;max-width:620px;
  margin:auto 0 0;
  padding:0 24px;
  text-align:center;
  flex:1;display:flex;flex-direction:column;justify-content:center;
}
.center-block h1{font-size:30px;font-weight:600;letter-spacing:-0.4px;line-height:1.25;}
.center-block p{color:var(--text-muted);font-size:14.5px;margin-top:10px;}

.banner{
  background:var(--surface);border:1px solid var(--border);border-radius:10px;
  padding:12px 14px;font-size:13px;color:var(--text-muted);
  margin-top:18px;text-align:left;
}
.banner a{color:var(--text);text-decoration:underline;text-decoration-color:var(--border);cursor:pointer;}

.input-pill{
  margin-top:22px;
  background:var(--surface);border:1px solid var(--border);
  border-radius:14px;padding:12px 14px;
  display:flex;align-items:center;gap:10px;
}
.input-pill .text-input{
  flex:1;background:none;border:none;outline:none;color:var(--text);
  font-size:14px;font-family:inherit;
}
.input-pill .text-input::placeholder{color:var(--text-faint);}
.input-pill .text-input:disabled{opacity:0.5;}
.send-btn{
  width:28px;height:28px;border-radius:50%;background:var(--surface-2);
  border:1px solid var(--border);display:flex;align-items:center;justify-content:center;
  color:var(--text-muted);cursor:pointer;flex-shrink:0;font-size:12px;
}
.send-btn:hover:not(:disabled){color:var(--text);}
.send-btn:disabled{opacity:0.5;cursor:default;}

.tool-toggle-row{margin-top:10px;display:flex;justify-content:center;}
.chat-view .tool-toggle-row{justify-content:flex-start;margin:8px 0 16px;}
.tool-toggle{display:flex;align-items:center;gap:6px;font-size:12px;color:var(--text-muted);cursor:pointer;}
.tool-toggle input{accent-color:var(--blue);cursor:pointer;}

.chips{margin-top:14px;display:flex;gap:8px;justify-content:center;flex-wrap:wrap;}
.chip{
  display:flex;align-items:center;gap:6px;
  border:1px solid var(--border);border-radius:100px;
  padding:7px 13px;font-size:12.5px;color:var(--text-muted);cursor:pointer;
}
.chip:hover{background:var(--surface);color:var(--text);}
.chip.active-chip{background:var(--surface);color:var(--text);border-color:var(--text-faint);}
.chip .dot{width:6px;height:6px;border-radius:50%;flex-shrink:0;}

.status-line{
  margin-top:20px;font-size:12px;color:var(--text-faint);
  display:flex;align-items:center;justify-content:center;gap:7px;
}
.status-line .dot{width:5px;height:5px;border-radius:50%;background:var(--teal);flex-shrink:0;}

/* ===== chat view ===== */
.chat-view{
  width:100%;max-width:720px;margin:0 auto;
  display:flex;flex-direction:column;flex:1;
  padding:20px 24px 0;overflow:hidden;
}
.chat-log{flex:1;overflow-y:auto;padding:6px 2px 16px;display:flex;flex-direction:column;gap:14px;}
.msg{max-width:85%;font-size:14px;line-height:1.6;padding:12px 14px;border-radius:12px;white-space:pre-wrap;}
.msg.user{align-self:flex-end;background:var(--surface-2);}
.msg.assistant{align-self:flex-start;background:var(--surface);border:1px solid var(--border);}

.source-tags{display:flex;gap:6px;flex-wrap:wrap;margin-top:9px;}
.source-tag{
  font-size:10.5px;color:var(--text-faint);border:1px solid var(--border);
  border-radius:100px;padding:2px 8px;
}
.spin{display:inline-block;animation:spin 1s linear infinite;}
@keyframes spin{to{transform:rotate(360deg);}}

/* ===== navigator ===== */
.nav-pane{width:100%;max-width:620px;margin:0 auto;padding:28px 24px 50px;}
.panel-subtitle{font-size:12px;color:var(--text-faint);margin-bottom:14px;}

.field-grid{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-top:6px;}
.field{display:flex;flex-direction:column;gap:5px;}
.field.full-span{grid-column:1 / -1;margin-top:10px;}
.field label{font-size:11.5px;color:var(--text-faint);}
.field-input{
  background:var(--surface);border:1px solid var(--border);border-radius:8px;
  padding:9px 11px;color:var(--text);font-size:13px;font-family:inherit;outline:none;width:100%;
}
.field-input:focus{border-color:var(--blue);}
.drill-textarea{resize:vertical;line-height:1.5;}

.run-btn{
  margin-top:16px;width:100%;background:var(--blue);color:#0A0A0A;font-weight:600;
  border:none;border-radius:10px;padding:11px;font-size:13.5px;cursor:pointer;font-family:inherit;
}
.run-btn:hover:not(:disabled){filter:brightness(1.08);}
.run-btn:disabled{opacity:0.6;cursor:default;}

.error-line{color:#FF6B5B;font-size:13px;margin-top:12px;}

.result-block{margin-top:22px;border-top:1px solid var(--border);padding-top:18px;}
.verdict-pill{
  display:inline-flex;align-items:center;gap:8px;border-radius:100px;
  padding:6px 14px;font-size:12.5px;font-weight:600;
}
.vdot{width:7px;height:7px;border-radius:50%;flex-shrink:0;}
.result-sub{margin-top:16px;}
.section-title{font-size:12.5px;color:var(--text-muted);margin-bottom:6px;font-weight:600;}
.status-pill{font-size:11px;border-radius:100px;padding:2px 9px;}
.result-reasoning{font-size:13px;color:var(--text-muted);margin-top:6px;line-height:1.55;}
.result-citation{font-size:11.5px;color:var(--text-faint);margin-top:4px;font-style:italic;}
.flag-item{margin-top:8px;}
.flag-title{font-size:13px;font-weight:600;}
.flag-explain{font-size:12.5px;color:var(--text-muted);margin-top:2px;}
.steps{margin-top:6px;padding-left:18px;font-size:13px;color:var(--text-muted);line-height:1.6;}
.steps.good-list li{color:var(--green);}
.steps.missed-list li{color:var(--red);}

/* ===== case browser ===== */
.browser-list{display:flex;flex-direction:column;gap:8px;}
.browser-item{
  background:var(--surface);border:1px solid var(--border);border-radius:10px;
  padding:12px 14px;cursor:pointer;
}
.browser-item:hover{background:var(--surface-2);}
.browser-item.expanded{background:var(--surface-2);}
.browser-item-head{display:flex;align-items:center;justify-content:space-between;gap:10px;}
.browser-item-title{font-size:13.5px;font-weight:500;}
.browser-item-body{
  margin-top:10px;font-size:13px;color:var(--text-muted);line-height:1.6;
  white-space:pre-wrap;border-top:1px solid var(--border);padding-top:10px;
}

/* ===== study mode ===== */
.study-topbar{display:flex;align-items:center;gap:14px;}
.mini-back-btn{
  background:none;border:1px solid var(--border);border-radius:8px;color:var(--text-muted);
  font-size:12px;padding:6px 10px;cursor:pointer;font-family:inherit;
}
.mini-back-btn:hover{color:var(--text);}

.study-pick-grid{display:grid;grid-template-columns:1fr 1fr 1fr;gap:12px;margin-top:16px;}
.study-pick-card{
  background:var(--surface);border:1px solid var(--border);border-radius:14px;
  padding:20px;cursor:pointer;
}
.study-pick-card:hover{background:var(--surface-2);}
.study-pick-card h3{font-size:15.5px;font-weight:600;margin-bottom:6px;}
.study-pick-card p{font-size:12.5px;color:var(--text-muted);line-height:1.5;}

.flashcard{perspective:1000px;height:260px;margin-top:4px;cursor:pointer;}
.flashcard-inner{position:relative;width:100%;height:100%;transition:transform .4s;transform-style:preserve-3d;}
.flashcard.flipped .flashcard-inner{transform:rotateY(180deg);}
.flashcard-face{
  position:absolute;inset:0;backface-visibility:hidden;
  background:var(--surface);border:1px solid var(--border);border-radius:14px;
  padding:24px;display:flex;flex-direction:column;gap:10px;
}
.flashcard-face.front{justify-content:center;}
.flashcard-face.back{transform:rotateY(180deg);overflow-y:auto;justify-content:flex-start;}
.flashcard-face h3{font-size:17px;font-weight:600;}
.flashcard-face p{font-size:13.5px;color:var(--text-muted);line-height:1.6;}
.flip-hint{font-size:11.5px;color:var(--text-faint);margin-top:auto;}
.flash-controls{display:flex;justify-content:space-between;margin-top:16px;gap:10px;}

.rate-prompt{font-size:12.5px;color:var(--text-faint);margin-top:16px;text-align:center;}
.rate-row{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;margin-top:10px;}
.rate-btn{
  border:1px solid var(--border);border-radius:10px;padding:10px 6px;
  font-size:12.5px;font-weight:600;cursor:pointer;font-family:inherit;background:var(--surface);
}
.rate-btn.again{color:var(--red);}
.rate-btn.hard{color:var(--amber);}
.rate-btn.good{color:var(--blue);}
.rate-btn.easy{color:var(--green);}
.rate-btn:hover{background:var(--surface-2);}

.srs-done{
  background:var(--surface);border:1px solid var(--border);border-radius:14px;
  padding:28px;text-align:center;margin-top:6px;
}
.srs-done h3{font-size:16px;font-weight:600;margin-bottom:6px;}
.srs-done p{font-size:13px;color:var(--text-muted);}

.quiz-question{font-size:14.5px;line-height:1.6;margin-bottom:14px;}
.quiz-answer{resize:vertical;margin-bottom:14px;font-family:inherit;line-height:1.5;}

/* ===== settings modal ===== */
.modal-overlay{
  position:fixed;inset:0;background:rgba(0,0,0,0.65);
  display:flex;align-items:center;justify-content:center;z-index:50;padding:20px;
}
.modal{
  background:var(--surface);border:1px solid var(--border);border-radius:14px;
  padding:24px;max-width:440px;width:100%;
}
.modal h2{font-size:16px;font-weight:600;margin-bottom:10px;}
.modal p{font-size:13px;color:var(--text-muted);line-height:1.6;margin-bottom:14px;}
.modal p a{color:var(--blue);}
.modal-actions{display:flex;justify-content:flex-end;gap:10px;margin-top:14px;}
.btn-primary{
  background:var(--blue);color:#0A0A0A;border:none;border-radius:8px;
  padding:9px 16px;font-size:13px;font-weight:600;cursor:pointer;font-family:inherit;
}
.btn-secondary{
  background:none;border:1px solid var(--border);color:var(--text-muted);
  border-radius:8px;padding:9px 16px;font-size:13px;cursor:pointer;font-family:inherit;
}