/* HomeworkMint v3: chat-style layout. Mint green accent. */
:root{--bg:#f6faf8;--side:#eef6f2;--card:#fff;--text:#14231d;--muted:#5d6f67;--line:#dbe8e1;--mint:#0f9f74;--mint-2:#0b7d5c;--mint-soft:#d9f3e8;--warn:#b45309;--err:#c62828;--r:16px;--sbw:268px}
*{box-sizing:border-box}
html,body{height:100%}
body{margin:0;font:16px/1.55 system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;color:var(--text);background:var(--bg)}
a{color:var(--mint-2)}
button{font:inherit;cursor:pointer}
.muted{color:var(--muted)}.small{font-size:.86rem}
.app{display:flex;min-height:100vh}
/* sidebar */
.sidebar{width:var(--sbw);flex:0 0 var(--sbw);background:var(--side);border-right:1px solid var(--line);display:flex;flex-direction:column;gap:14px;padding:14px;position:sticky;top:0;height:100vh;overflow-y:auto;transition:margin-left .2s ease}
.app.collapsed .sidebar{margin-left:calc(-1 * var(--sbw))}
.sb-top{display:flex;align-items:center;justify-content:space-between}
.logo{display:flex;align-items:center;gap:8px;font-weight:800;font-size:1.12rem;color:var(--text);text-decoration:none}
.icon-btn{background:none;border:0;border-radius:10px;width:36px;height:36px;display:grid;place-items:center;font-size:1.15rem;color:var(--muted)}
.icon-btn:hover{background:rgba(15,159,116,.1);color:var(--mint-2)}
.new-chat{border:1px solid var(--line);background:#fff;border-radius:12px;padding:10px 12px;text-align:left;font-weight:600;color:var(--text)}
.new-chat:hover{border-color:var(--mint)}
.sb-label{font-size:.75rem;text-transform:uppercase;letter-spacing:.06em;color:var(--muted);font-weight:700;margin:2px 4px 6px}
.tool{display:flex;gap:10px;align-items:center;width:100%;background:none;border:0;border-radius:10px;padding:8px 10px;text-align:left;color:var(--text)}
.tool:hover,.tool.active{background:var(--mint-soft)}
.sb-recent{flex:1;min-height:80px}
.recent{list-style:none;margin:0;padding:0}
.recent li{display:flex;align-items:center;border-radius:10px}
.recent li:hover,.recent li.active{background:#fff}
.recent .open{flex:1;min-width:0;background:none;border:0;text-align:left;padding:7px 10px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;color:var(--text);font-size:.92rem}
.recent .del{background:none;border:0;color:var(--muted);padding:4px 8px;border-radius:8px;opacity:.6}
.recent .del:hover{opacity:1;color:var(--err)}
.sb-bottom{border-top:1px solid var(--line);padding-top:12px;display:flex;flex-direction:column;gap:8px}
.go-pro{background:linear-gradient(90deg,var(--mint),var(--mint-2));color:#fff;border:0;border-radius:12px;padding:10px 12px;font-weight:700;text-align:left}
.go-pro small{font-weight:500;opacity:.9;margin-left:4px}
.auth-area{display:flex;gap:8px}
.auth-area .btn{flex:1}
.sb-links a{color:var(--muted)}
.btn{display:inline-block;border:1px solid var(--line);background:#fff;color:var(--text);border-radius:10px;padding:9px 14px;font-weight:600;text-decoration:none}
.btn:hover{border-color:var(--mint)}
.btn.primary{background:var(--mint);border-color:var(--mint);color:#fff}
.btn.primary:hover{background:var(--mint-2)}
.small-btn{padding:7px 12px;font-size:.9rem}
/* main */
.main{flex:1;min-width:0;display:flex;flex-direction:column;min-height:100vh}
.topbar{display:flex;align-items:center;gap:10px;padding:10px 14px}
.topbar .btn{margin-left:auto}
.topbar-logo,#sb-open{display:none}
.app.collapsed #sb-open,.app.collapsed .topbar-logo{display:flex}
.hero{text-align:center;padding:9vh 20px 18px;max-width:820px;margin:0 auto}
.hero h1{font-size:clamp(1.6rem,4.2vw,2.5rem);line-height:1.2;margin:0 0 10px}
.accent{color:var(--mint)}
.dash{color:var(--muted);font-weight:400}
.lead{color:var(--muted);margin:0;font-size:1.05rem}
.composer-wrap{width:100%;max-width:780px;margin:0 auto;padding:0 18px}
.subjects{display:flex;gap:8px;justify-content:center;margin:10px 0 12px}
.subj{border:1px solid var(--line);background:#fff;border-radius:999px;padding:6px 16px;color:var(--muted);font-weight:600}
.subj.active{background:var(--mint);border-color:var(--mint);color:#fff}
.composer{background:#fff;border:1px solid var(--line);border-radius:22px;box-shadow:0 6px 24px rgba(15,80,60,.08);padding:10px}
.composer:focus-within{border-color:var(--mint)}
.composer-row{display:flex;align-items:flex-end;gap:8px}
.composer textarea{flex:1;border:0;outline:0;resize:none;font:inherit;font-size:1.05rem;padding:8px 4px;min-height:44px;max-height:220px;background:transparent;color:var(--text)}
.plus{background:var(--mint-soft);color:var(--mint-2);width:42px;height:42px;border-radius:50%}
.send{width:42px;height:42px;border-radius:50%;border:0;background:var(--mint);color:#fff;font-size:1.2rem;font-weight:700}
.send:disabled{opacity:.5;cursor:default}
.photo-chip{display:flex;align-items:center;gap:8px;padding:4px 6px 8px}
.photo-chip img{height:54px;border-radius:8px;border:1px solid var(--line)}
.examples{display:flex;flex-wrap:wrap;gap:8px;justify-content:center;margin:14px 0 6px}
.examples button{border:1px dashed var(--line);background:transparent;border-radius:999px;padding:5px 12px;color:var(--muted);font-size:.9rem}
.examples button:hover{border-color:var(--mint);color:var(--mint-2)}
.fine{text-align:center;max-width:640px;margin:8px auto 0}
.below{max-width:780px;margin:auto auto 0;padding:40px 18px 20px;width:100%}
.integrity{background:#fff;border:1px solid var(--line);border-radius:var(--r);padding:14px 18px}
.integrity h2{font-size:1.1rem;margin:0 0 6px}
.integrity p{margin:0;color:var(--muted)}
footer{text-align:center;color:var(--muted);font-size:.9rem;padding:18px 0 4px}
footer a{color:var(--muted)}
/* chat mode */
.app.chatting .hero,.app.chatting .examples,.app.chatting .below{display:none}
.app.chatting .composer-wrap{position:sticky;bottom:0;background:linear-gradient(transparent,var(--bg) 22%);padding-top:18px;padding-bottom:12px}
.app.chatting .fine{font-size:.76rem;margin-top:6px}
.thread{flex:1;width:100%;max-width:780px;margin:0 auto;padding:10px 18px 10px;display:flex;flex-direction:column;gap:14px}
.msg{max-width:92%;border-radius:18px;padding:10px 14px;overflow-wrap:anywhere}
.msg.user{align-self:flex-end;background:var(--mint);color:#fff;border-bottom-right-radius:6px;white-space:pre-wrap}
.msg.user img{display:block;max-width:220px;border-radius:10px;margin-bottom:6px}
.msg.bot{align-self:flex-start;background:#fff;border:1px solid var(--line);border-bottom-left-radius:6px;max-width:100%}
.msg.bot .tag{display:inline-block;font-size:.72rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em;color:var(--mint-2);background:var(--mint-soft);border-radius:999px;padding:1px 8px;margin-bottom:6px}
.msg.bot .tag.warn{color:var(--warn);background:#fdf0dc}
.msg.bot p{margin:.45em 0}.msg.bot h3,.msg.bot h4{margin:.7em 0 .3em;font-size:1.02rem}
.msg.bot ol,.msg.bot ul{padding-left:1.3em;margin:.4em 0}
.msg.bot code{background:#eef4f1;padding:1px 5px;border-radius:5px}
.msg.bot pre{background:#eef4f1;padding:10px;border-radius:10px;overflow-x:auto}
.msg.bot .katex-display{overflow-x:auto;overflow-y:hidden;padding:2px 0}
.msg.bot .answer{font-size:1.15rem;font-weight:700}
.msg.bot .actions{display:flex;gap:8px;flex-wrap:wrap;margin-top:8px}
.msg.bot .actions button{border:1px solid var(--line);background:#fff;border-radius:999px;padding:4px 12px;font-size:.88rem;color:var(--mint-2)}
.msg.bot .notice{background:#fff8ec;border:1px solid #f5dfb8;border-radius:10px;padding:8px 10px;margin:4px 0}
.stats{display:flex;flex-wrap:wrap;gap:8px;margin:6px 0}
.stat{background:var(--mint-soft);border-radius:10px;padding:4px 10px;font-size:.9rem}
.typing span{display:inline-block;width:7px;height:7px;margin:0 2px;border-radius:50%;background:var(--mint);animation:b 1s infinite ease-in-out}
.typing span:nth-child(2){animation-delay:.15s}.typing span:nth-child(3){animation-delay:.3s}
@keyframes b{0%,80%,100%{opacity:.25}40%{opacity:1}}
/* pricing modal */
.modal{position:fixed;inset:0;background:rgba(10,30,22,.45);display:grid;place-items:center;padding:16px;z-index:50}
.modal[hidden]{display:none}
.modal-card{position:relative;background:#fff;border-radius:20px;max-width:900px;width:100%;max-height:92vh;overflow-y:auto;padding:22px}
.modal-card h2{margin:0 0 14px}
.modal-x{position:absolute;top:10px;right:10px}
.plans{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}
.plan{position:relative;border:1px solid var(--line);border-radius:16px;padding:16px;display:flex;flex-direction:column}
.plan h3{margin:0 0 4px}
.plan ul{padding-left:1.1em;margin:10px 0 16px;flex:1;color:var(--muted);font-size:.94rem}
.plan .btn{text-align:center}
.price{font-size:1.9rem;font-weight:800}.price small{font-size:.95rem;font-weight:500;color:var(--muted)}
.billed{margin:0;color:var(--muted);font-size:.9rem}.billed strong{color:var(--mint-2)}
.plan.featured{border:2px solid var(--mint);background:#f3fbf7}
.badge{position:absolute;top:-11px;right:14px;background:var(--mint);color:#fff;font-size:.75rem;font-weight:700;border-radius:999px;padding:2px 10px}
.scrim{display:none}
/* mobile: slide-out sidebar */
@media (max-width:800px){
  .sidebar{position:fixed;left:0;top:0;z-index:40;transform:translateX(-100%);transition:transform .22s ease;box-shadow:4px 0 24px rgba(0,0,0,.12);margin-left:0!important}
  .app.menu-open .sidebar{transform:none}
  .app.menu-open .scrim{display:block;position:fixed;inset:0;background:rgba(10,30,22,.35);z-index:30}
  #sb-open,.topbar-logo{display:flex}
  .hero{padding-top:5vh}
  .plans{grid-template-columns:1fr}
  .plan.featured{order:-1}
  .msg{max-width:100%}
}
.wsub{display:flex;gap:6px;justify-content:center;align-items:center;margin:-2px 0 10px;flex-wrap:wrap}
.wsub button{border:1px solid var(--line);background:#fff;border-radius:10px;padding:4px 12px;font-size:.9rem;color:var(--muted)}
.wsub button.active{border-color:var(--mint);color:var(--mint-2);background:var(--mint-soft);font-weight:600}
.checked-text{background:#fbfdfc;border:1px solid var(--line);border-radius:12px;padding:10px 12px;line-height:1.75;margin:8px 0}
mark.hl{background:#fde7b0;border-bottom:2px solid #e3a008;border-radius:3px;padding:0 1px;cursor:pointer;color:inherit}
mark.hl:hover,mark.hl:focus,mark.hl.sel{background:#fbcf6e;outline:none}
.hl-detail{background:#f3fbf7;border-radius:10px;padding:8px 10px;color:var(--text)}
.meter{display:flex;align-items:center;gap:4px;margin:4px 0}
.meter span{width:42px;height:8px;border-radius:4px;background:#e5ece8}
.meter b{margin-left:8px;font-size:.92rem}
.meter.m-low span:nth-child(1){background:#16a34a}
.meter.m-medium span:nth-child(-n+2){background:#e3a008}
.meter.m-high span:nth-child(-n+3){background:#dc6b20}
.disclaimer{background:#f6f6f6;border-radius:10px;padding:8px 10px;margin:10px 0 0;color:var(--muted)}
[hidden]{display:none!important}
.app.chatting .composer-wrap{background:var(--bg);box-shadow:0 -10px 16px -6px var(--bg);padding-top:6px;border-top:1px solid transparent}
.app.chatting .subjects{margin:6px 0 8px}
.app.chatting .subj{padding:3px 12px;font-size:.88rem}
.thread{padding-bottom:20px}