*{margin:0;padding:0;box-sizing:border-box}
:root{
  --bg:#000000;--surface:#0d1117;--surface2:#161b22;
  --border:rgba(0,207,255,0.15);--cyan:#00cfff;--orange:#ff8c00;
  --text:#ffffff;--muted:#ffffff;--success:#3fb950;--danger:#f85149;--purple:#9b59f5;
}
body{background:var(--bg);font-family:'Rajdhani',sans-serif;color:var(--text);min-height:100vh;overflow-x:hidden}
canvas#bg{position:fixed;top:0;left:0;width:100%;height:100%;pointer-events:none;z-index:0}
.page{position:relative;z-index:1;min-height:100vh}

/* FLASH */
.flash-container{position:fixed;top:80px;right:20px;z-index:999;display:flex;flex-direction:column;gap:8px;max-width:360px}
.flash{padding:12px 16px;border-radius:8px;font-size:13px;font-family:'Inter',sans-serif;transition:opacity .5s;line-height:1.5;word-break:break-word}
.flash-success{background:rgba(63,185,80,.12);border:.5px solid var(--success);color:var(--success)}
.flash-danger{background:rgba(248,81,73,.12);border:.5px solid var(--danger);color:var(--danger)}
.flash-info{background:rgba(0,207,255,.12);border:.5px solid var(--cyan);color:var(--cyan)}
.flash-warning{background:rgba(255,140,0,.12);border:.5px solid var(--orange);color:var(--orange)}

/* NAV */
.nav{display:flex;align-items:center;justify-content:space-between;padding:10px 20px;border-bottom:.5px solid var(--border);background:rgba(0,0,0,.93);backdrop-filter:blur(14px);position:sticky;top:0;z-index:100}
.nav-logo{display:flex;align-items:center;text-decoration:none}
.nav-logo img{height:52px;width:auto;object-fit:contain}
.nav-logo-text{font-size:20px;font-weight:700;letter-spacing:2px;color:var(--cyan);margin-left:10px}
.nav-tabs{display:flex;gap:4px}
.nav-tab{padding:7px 18px;border-radius:6px;border:.5px solid transparent;font-size:15px;cursor:pointer;color:var(--muted);transition:all .2s;background:transparent;font-family:inherit;letter-spacing:1px;text-decoration:none;display:inline-block}
.nav-tab:hover,.nav-tab.active{color:var(--cyan);border-color:var(--border);background:rgba(0,207,255,.06)}
.nav-right{display:flex;align-items:center;gap:10px}
.badge-exam-pdf{font-size:11px;padding:3px 12px;border-radius:20px;border:1px solid var(--orange);color:var(--orange);background:rgba(255,140,0,.08);letter-spacing:1px;cursor:pointer;transition:background .2s}
.badge-exam-pdf:hover{background:rgba(255,140,0,.18)}
.btn-icon{width:34px;height:34px;border-radius:8px;border:.5px solid var(--border);background:transparent;color:var(--muted);cursor:pointer;display:flex;align-items:center;justify-content:center;font-size:16px;transition:all .2s;text-decoration:none}
.btn-icon:hover{color:var(--cyan);border-color:var(--cyan)}

/* HERO */
.hero{text-align:center;padding:68px 24px 40px}
.hero-badge{display:inline-block;font-size:11px;letter-spacing:3px;color:var(--cyan);border:1px solid var(--border);padding:6px 18px;border-radius:20px;margin-bottom:24px;background:rgba(0,207,255,.05)}
.hero-title{font-size:54px;font-weight:700;line-height:1.1;letter-spacing:3px;margin-bottom:14px}
.hero-title span{color:var(--cyan)}
.hero-sub{font-size:16px;color:var(--muted);max-width:500px;margin:0 auto 36px;line-height:1.6;font-family:'Inter',sans-serif;font-weight:300}
.hero-btns{display:flex;gap:12px;justify-content:center;flex-wrap:wrap}
.btn-primary{padding:13px 34px;background:var(--cyan);color:#000000;border:none;border-radius:8px;font-weight:700;font-size:15px;cursor:pointer;letter-spacing:1px;font-family:inherit;transition:all .2s;text-decoration:none;display:inline-block}
.btn-primary:hover{background:#33d9ff;transform:translateY(-1px)}
.btn-outline{padding:13px 34px;background:transparent;color:var(--cyan);border:1px solid var(--cyan);border-radius:8px;font-weight:600;font-size:15px;cursor:pointer;letter-spacing:1px;font-family:inherit;transition:all .2s;text-decoration:none;display:inline-block}
.btn-outline:hover{background:rgba(0,207,255,.08)}
.trial-note{font-size:12px;color:var(--muted);margin-top:10px;font-family:'Inter',sans-serif}

/* PROMO */
.promo-section{padding:60px 28px;max-width:1100px;margin:0 auto;display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.promo-card{background:var(--surface);border:.5px solid var(--border);border-radius:16px;padding:32px 24px;text-align:center;position:relative;overflow:hidden;transition:all .3s}
.promo-card:hover{transform:translateY(-4px);border-color:rgba(0,207,255,.35)}
.promo-card::before{content:'';position:absolute;top:0;left:0;right:0;height:2px}
.promo-card:nth-child(1)::before{background:linear-gradient(90deg,var(--cyan),var(--purple))}
.promo-card:nth-child(2)::before{background:linear-gradient(90deg,var(--success),var(--cyan))}
.promo-card:nth-child(3)::before{background:linear-gradient(90deg,var(--orange),#ff4444)}
.promo-icon{font-size:40px;margin-bottom:16px;display:block}
.promo-title{font-size:18px;font-weight:700;letter-spacing:2px;line-height:1.3;margin-bottom:12px;color:var(--text)}
.promo-title span.c{color:var(--cyan)}
.promo-title span.g{color:var(--success)}
.promo-title span.o{color:var(--orange)}
.promo-desc{font-size:13px;color:var(--muted);font-family:'Inter',sans-serif;line-height:1.6}

/* PLANS */
.plans-section{padding:20px 20px 60px;max-width:1000px;margin:0 auto}
.section-title{text-align:center;font-size:12px;letter-spacing:3px;color:var(--muted);margin-bottom:8px}
.section-subtitle{text-align:center;font-size:22px;font-weight:700;letter-spacing:2px;margin-bottom:28px;color:var(--text)}
.plans-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}
.plan-card{background:var(--surface);border:.5px solid var(--border);border-radius:14px;padding:22px 16px;text-align:center;cursor:pointer;transition:all .25s;position:relative}
.plan-card:hover{border-color:var(--cyan);background:rgba(0,207,255,.04);transform:translateY(-2px)}
.plan-card.featured{border:1.5px solid var(--cyan)}
.plan-card.professor{border-color:rgba(255,140,0,.25)}
.plan-card.professor:hover{border-color:var(--orange);background:rgba(255,140,0,.04)}
.plan-card.free{border-color:rgba(63,185,80,.3)}
.plan-card.free:hover{border-color:var(--success);background:rgba(63,185,80,.04)}
.plan-featured-badge{position:absolute;top:-10px;left:50%;transform:translateX(-50%);background:var(--cyan);color:#000000;font-size:9px;font-weight:700;padding:3px 12px;border-radius:10px;letter-spacing:1px;white-space:nowrap}
.plan-name{font-size:12px;font-weight:700;letter-spacing:2px;color:var(--muted);margin-bottom:8px}
.plan-price{font-size:28px;font-weight:700;color:var(--text);line-height:1.2}
.plan-price span{font-size:12px;color:var(--muted);font-weight:400}
.plan-features{margin-top:12px;text-align:left}
.plan-feature{font-size:11px;color:var(--muted);padding:3px 0;display:flex;align-items:flex-start;gap:6px;font-family:'Inter',sans-serif;line-height:1.4}
.plan-feature::before{content:'✓';color:var(--success);font-size:10px;flex-shrink:0;margin-top:1px}
.plan-feature.no::before{content:'✕';color:var(--danger)}
.plan-btn{margin-top:14px;width:100%;padding:9px;border-radius:7px;background:var(--cyan);color:#000000;border:none;font-weight:700;font-size:12px;cursor:pointer;font-family:inherit;letter-spacing:1px;transition:all .2s}
.plan-btn:hover{opacity:.9}
.plan-btn.free-btn{background:var(--success)}
.plan-card.professor .plan-btn{background:var(--orange)}

/* TICKER */
.ticker-wrap{background:var(--surface);border-top:.5px solid var(--border);border-bottom:.5px solid var(--border);padding:14px 0;overflow:hidden;position:relative}
.ticker-wrap::before{content:'';position:absolute;left:0;top:0;bottom:0;width:80px;background:linear-gradient(90deg,var(--surface),transparent);z-index:2}
.ticker-wrap::after{content:'';position:absolute;right:0;top:0;bottom:0;width:80px;background:linear-gradient(270deg,var(--surface),transparent);z-index:2}
.ticker-track{display:flex;gap:0;animation:ticker 300s linear infinite;width:max-content}
.ticker-track:hover{animation-play-state:paused}
.ticker-item{display:flex;align-items:center;gap:8px;padding:0 28px;font-size:12px;color:var(--muted);white-space:nowrap;font-family:'Inter',sans-serif;border-right:.5px solid var(--border)}
.ticker-item strong{color:var(--text);font-family:'Rajdhani',sans-serif;letter-spacing:1px;font-size:13px}
.ticker-item .dot-cat{width:6px;height:6px;border-radius:50%;flex-shrink:0}
@keyframes ticker{0%{transform:translateX(0)}100%{transform:translateX(-50%)}}

/* FOOTER */
.footer{background:var(--surface);border-top:.5px solid var(--border);padding:24px 28px;text-align:center}
.footer-text{font-size:12px;color:var(--muted);font-family:'Inter',sans-serif}
.footer-logo{font-size:16px;font-weight:700;letter-spacing:2px;color:var(--cyan);margin-bottom:6px}

/* AUTH */
.auth-wrap{min-height:calc(100vh - 65px);display:flex;align-items:center;justify-content:center;padding:40px 20px}
.auth-card{background:var(--surface);border:.5px solid var(--border);border-radius:16px;padding:36px 30px;width:100%;max-width:400px}
.auth-logo{text-align:center;margin-bottom:20px}
.auth-logo img{height:60px;width:auto}
.auth-title{font-size:22px;font-weight:700;letter-spacing:2px;margin-bottom:4px}
.auth-sub{font-size:13px;color:var(--muted);font-family:'Inter',sans-serif;margin-bottom:20px}
.form-group{margin-bottom:16px}
.form-label{font-size:11px;letter-spacing:1px;color:var(--muted);margin-bottom:6px;display:block}
.form-input{width:100%;padding:11px 14px;background:var(--surface2);border:.5px solid var(--border);border-radius:8px;color:var(--text);font-size:14px;font-family:'Inter',sans-serif;outline:none;transition:border-color .2s}
.form-input:focus{border-color:var(--cyan)}
.form-select{width:100%;padding:11px 14px;background:var(--surface2);border:.5px solid var(--border);border-radius:8px;color:var(--text);font-size:14px;font-family:'Inter',sans-serif;outline:none}
.form-submit{width:100%;padding:12px;background:var(--cyan);color:#000000;border:none;border-radius:8px;font-weight:700;font-size:14px;cursor:pointer;font-family:inherit;letter-spacing:1px;margin-top:6px;transition:all .2s}
.form-submit:hover{background:#33d9ff}
.auth-links{display:flex;justify-content:space-between;margin-top:16px}
.auth-link{font-size:12px;color:var(--cyan);cursor:pointer;font-family:'Inter',sans-serif;text-decoration:none}
.auth-link:hover{text-decoration:underline}
.auth-back{font-size:12px;color:var(--muted);font-family:'Inter',sans-serif;text-align:center;margin-top:14px;text-decoration:none;display:block}
.auth-back:hover{color:var(--cyan)}
.recover-back{display:flex;align-items:center;gap:6px;color:var(--muted);font-size:13px;margin-bottom:18px;text-decoration:none}
.recover-back:hover{color:var(--cyan)}
.user-type-grid{display:grid;grid-template-columns:1fr 1fr;gap:8px;margin-top:6px}
.user-type-btn{padding:14px 10px;border-radius:10px;border:.5px solid var(--border);background:var(--surface2);color:var(--muted);cursor:pointer;font-family:inherit;font-size:13px;letter-spacing:1px;text-align:center;transition:all .2s}
.user-type-btn:hover{border-color:var(--cyan);color:var(--cyan)}
.user-type-btn.selected{border-color:var(--cyan);background:rgba(0,207,255,.08);color:var(--cyan)}
.user-type-icon{font-size:22px;display:block;margin-bottom:6px}

/* CHAT */
.chat-layout{display:grid;grid-template-columns:220px 1fr;min-height:calc(100vh - 65px);transition:grid-template-columns .25s}
.chat-layout.sidebar-collapsed{grid-template-columns:0px 1fr}
.chat-layout.sidebar-collapsed .sidebar{width:0;padding:0;overflow:hidden;border:none}
.sidebar-collapse-btn{position:fixed;top:80px;left:208px;z-index:200;width:24px;height:24px;border-radius:50%;background:var(--surface);border:.5px solid var(--border);color:var(--muted);cursor:pointer;font-size:12px;display:flex;align-items:center;justify-content:center;transition:left .25s}
.chat-layout.sidebar-collapsed .sidebar-collapse-btn{left:0px}
.sidebar{position:relative;transition:all .25s}
.sidebar{background:var(--surface);border-right:.5px solid var(--border);padding:16px;overflow-y:auto}
.sidebar-title{font-size:10px;letter-spacing:2px;color:var(--muted);margin-bottom:10px}
.mode-btn{display:flex;align-items:center;gap:8px;width:100%;padding:10px 12px;border-radius:8px;border:.5px solid transparent;background:transparent;color:var(--muted);cursor:pointer;font-size:12px;font-family:inherit;margin-bottom:4px;transition:all .2s;text-align:left;letter-spacing:1px}
.mode-btn:hover,.mode-btn.active{background:rgba(0,207,255,.06);border-color:var(--border);color:var(--cyan)}
.mode-btn.professor-btn:hover,.mode-btn.professor-btn.active{background:rgba(255,140,0,.06);border-color:rgba(255,140,0,.2);color:var(--orange)}
.sidebar-sep{height:.5px;background:var(--border);margin:12px 0}
.hist-item{padding:8px 10px;border-radius:6px;font-size:11px;color:var(--muted);cursor:pointer;font-family:'Inter',sans-serif;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;transition:all .2s}
.hist-item:hover{background:rgba(255,255,255,.04);color:var(--text)}
.hist-item.active{background:rgba(0,207,255,.06);color:var(--cyan)}
.hist-delete{float:right;opacity:0.4;cursor:pointer;font-size:11px;padding:0 4px}
.hist-delete:hover{opacity:1;color:var(--danger)}
.new-conv-btn{width:100%;padding:8px;border-radius:7px;background:transparent;border:.5px solid var(--border);color:var(--muted);cursor:pointer;font-size:11px;font-family:inherit;letter-spacing:1px;margin-bottom:10px;transition:all .2s}
.new-conv-btn:hover{border-color:var(--cyan);color:var(--cyan)}
.chat-main{display:flex;flex-direction:column;height:calc(100vh - 65px)}
.chat-header{padding:14px 20px;border-bottom:.5px solid var(--border);display:flex;align-items:center;justify-content:space-between;flex-shrink:0}
.chat-mode-label{font-size:12px;font-weight:700;letter-spacing:2px;color:var(--cyan)}
.messages{flex:1;padding:20px;padding-bottom:100px;overflow-y:auto;display:flex;flex-direction:column;gap:16px}
.msg{display:flex;gap:10px;align-items:flex-start}
.msg.user{flex-direction:row-reverse}
.msg-avatar{width:30px;height:30px;border-radius:8px;display:flex;align-items:center;justify-content:center;flex-shrink:0;overflow:hidden}
.msg-avatar.ia{background:rgba(0,207,255,.08);border:.5px solid var(--border)}
.msg-avatar.ia img{width:24px;height:24px;object-fit:contain}
.msg-avatar.user{background:rgba(255,140,0,.1);border:.5px solid rgba(255,140,0,.2);color:var(--orange);font-size:13px;font-weight:700;font-family:'Rajdhani',sans-serif}
.msg-bubble{max-width:72%;padding:10px 14px;border-radius:10px;font-size:14px;line-height:1.6;font-family:'Inter',sans-serif}
.msg-bubble.ia{background:var(--surface2);border:.5px solid var(--border);color:var(--text)}
.msg-bubble.user{background:rgba(0,207,255,.08);border:.5px solid rgba(0,207,255,.2);color:var(--text)}
.thinking{display:flex;gap:5px;align-items:center;padding:2px 0}
.dot{width:7px;height:7px;border-radius:50%;background:var(--cyan);animation:pulse 1.4s ease-in-out infinite}
.dot:nth-child(2){animation-delay:.2s}.dot:nth-child(3){animation-delay:.4s}
@keyframes pulse{0%,100%{opacity:.2;transform:scale(.8);box-shadow:0 0 2px var(--cyan)}50%{opacity:1;transform:scale(1.2);box-shadow:0 0 10px var(--cyan)}}
.chat-input-area{position:fixed;bottom:20px;left:0;right:0;z-index:100;background:var(--bg);padding:8px 12px 10px;border-top:.5px solid var(--border);display:flex;gap:10px;align-items:flex-end;max-width:800px;margin:0 auto}
#mode-chat .chat-input-area{left:220px;max-width:800px;margin:0 auto}
.chat-input{flex:1;background:var(--surface2);border:.5px solid var(--border);border-radius:10px;padding:7px 10px;color:var(--text);font-size:12px;font-family:'Inter',sans-serif;outline:none;resize:none;min-height:34px;max-height:120px;transition:border-color .2s}
.chat-input:focus{border-color:var(--cyan)}
.send-btn{width:34px;height:34px;background:var(--cyan);border:none;border-radius:8px;cursor:pointer;color:#000000;font-size:15px;flex-shrink:0;transition:all .2s}
.send-btn:hover{background:#33d9ff}
.send-btn:disabled{opacity:.4;cursor:not-allowed}

/* EMPTY STATE (ChatGPT-style) */
.empty-welcome{display:none;flex:1;flex-direction:column;align-items:center;justify-content:center;text-align:center;padding:40px 20px}
.empty-title{font-size:22px;font-weight:700;letter-spacing:2px;color:var(--text);margin-bottom:8px}
.empty-sub{font-size:13px;color:var(--muted);font-family:'Inter',sans-serif}
.chat-main.chat-empty .empty-welcome{display:flex}
.chat-main.chat-empty .messages{display:none!important}
.chat-main.chat-empty .chat-input-area{border-top:none}
.exam-wrap .chat-main{padding-bottom:80px}
/* UPLOAD BUTTON */
.upload-btn{width:42px;height:42px;background:var(--surface2);border:.5px solid var(--border);border-radius:10px;cursor:pointer;color:var(--muted);font-size:18px;flex-shrink:0;display:flex;align-items:center;justify-content:center;transition:all .2s;line-height:1}
.upload-btn:hover{color:var(--cyan);border-color:var(--cyan)}

/* EXAM */
.exam-wrap{height:calc(100vh - 65px);display:flex;flex-direction:column}
.exam-header-bar{background:rgba(255,140,0,.06);border:.5px solid rgba(255,140,0,.2);border-radius:10px;padding:6px 12px;margin:8px 12px 0;display:flex;align-items:center;justify-content:space-between;flex-shrink:0}
.exam-title{font-size:13px;font-weight:700;letter-spacing:2px;color:var(--orange)}
.exam-timer{font-size:22px;font-weight:700;color:var(--orange);font-family:'Courier New',monospace}
.exam-progress{padding:4px 12px 0;flex-shrink:0}
.progress-bar{height:3px;background:var(--surface2);border-radius:2px;margin-top:5px}
.progress-fill{height:100%;border-radius:2px;transition:width .5s}

/* PROFESSOR */
.prof-wrap{overflow-y:auto}
.prof-header{padding:14px 20px;border-bottom:.5px solid var(--border);background:rgba(255,140,0,.03)}
.prof-notice{background:rgba(255,140,0,.06);border:.5px solid rgba(255,140,0,.2);border-radius:8px;padding:10px 14px;margin:14px 20px 0;font-size:12px;color:var(--orange);font-family:'Inter',sans-serif;display:flex;align-items:center;gap:8px}
.prof-form{padding:16px 20px;display:grid;grid-template-columns:1fr 1fr;gap:12px}
.prof-form .form-group{margin:0}
.prof-form .full{grid-column:span 2}
.prof-output{margin:0 20px 20px;background:var(--surface2);border:.5px solid rgba(255,140,0,.2);border-radius:10px;padding:16px}
.prof-output-title{font-size:10px;letter-spacing:2px;color:var(--orange);margin-bottom:12px}
.prof-output-content{font-size:13px;color:var(--text);font-family:'Inter',sans-serif;line-height:1.8}

/* SETTINGS */
.settings-page{max-width:600px;padding:28px 24px}
.settings-title{font-size:18px;font-weight:700;letter-spacing:2px;margin-bottom:24px}
.settings-section{margin-bottom:26px}
.settings-section-title{font-size:10px;letter-spacing:2px;color:var(--muted);margin-bottom:12px;border-bottom:.5px solid var(--border);padding-bottom:8px}
.settings-row{display:flex;align-items:center;justify-content:space-between;padding:12px 0;border-bottom:.5px solid rgba(255,255,255,.04)}
.settings-label{font-size:14px;color:var(--text)}
.settings-desc{font-size:12px;color:var(--muted);font-family:'Inter',sans-serif;margin-top:2px}
.toggle{width:44px;height:24px;background:var(--surface2);border:.5px solid var(--border);border-radius:12px;cursor:pointer;position:relative;transition:all .2s;flex-shrink:0}
.toggle.on{background:rgba(0,207,255,.15);border-color:var(--cyan)}
.toggle::after{content:'';position:absolute;top:3px;left:3px;width:16px;height:16px;border-radius:50%;background:var(--muted);transition:all .2s}
.toggle.on::after{left:23px;background:var(--cyan)}
.plan-current{background:var(--surface);border:.5px solid var(--border);border-radius:10px;padding:16px;display:flex;align-items:center;justify-content:space-between}
.btn-sm{padding:7px 16px;background:transparent;border:1px solid var(--cyan);color:var(--cyan);border-radius:6px;font-size:11px;cursor:pointer;font-family:inherit;letter-spacing:1px;transition:all .2s;text-decoration:none;display:inline-block}
.btn-sm:hover{background:rgba(0,207,255,.08)}
.logout-btn{color:var(--danger);background:transparent;border:.5px solid var(--danger);padding:8px 18px;border-radius:6px;font-size:12px;cursor:pointer;font-family:'Rajdhani',sans-serif;letter-spacing:1px;text-decoration:none;display:inline-block}
.logout-btn:hover{background:rgba(248,81,73,.08)}

/* ── HAMBURGER & SIDEBAR TOGGLE ─────────────────────────────────────────── */
.nav-hamburger{display:none;background:transparent;border:.5px solid var(--border);color:var(--muted);width:34px;height:34px;border-radius:8px;cursor:pointer;font-size:18px;align-items:center;justify-content:center;flex-shrink:0;line-height:1}
.sidebar-toggle-btn{display:none;background:transparent;border:.5px solid var(--border);color:var(--muted);width:30px;height:30px;border-radius:6px;cursor:pointer;font-size:15px;align-items:center;justify-content:center;flex-shrink:0;line-height:1}
.sidebar-overlay{display:none;position:fixed;inset:0;background:rgba(0,0,0,.55);z-index:299}
.sidebar-overlay.open{display:block}

/* ── TABLET 769–1024px ─────────────────────────────────────────────────── */
@media(max-width:1024px){
  .nav-logo img{height:64px}
  .hero-title{font-size:42px}
  .promo-section{grid-template-columns:repeat(2,1fr)}
}

/* ── MOBILE ≤768px ──────────────────────────────────────────────────────── */
@media(max-width:768px){

  /* NAV */
  .nav{padding:10px 14px;position:relative}
  .nav-logo img{height:34px}
  .nav-hamburger{display:flex}
  .nav-tabs{
    display:none;flex-direction:column;gap:2px;
    position:absolute;top:100%;left:0;right:0;
    background:rgba(0,0,0,.97);border-bottom:.5px solid var(--border);
    padding:8px 14px 14px;z-index:200
  }
  .nav-tabs.open{display:flex}
  .nav-tab{width:100%;padding:10px 14px;text-align:left}

  /* HERO */
  .hero{padding:36px 16px 24px}
  .hero-title{font-size:28px;letter-spacing:1px}
  .hero-sub{font-size:14px;margin-bottom:24px}
  .hero-btns{flex-direction:column;align-items:center}
  .btn-primary,.btn-outline{width:100%;max-width:300px;text-align:center}

  /* PROMO */
  .promo-section{grid-template-columns:1fr;padding:24px 14px;gap:12px}

  /* PLANS */
  .plans-grid{grid-template-columns:1fr}
  .plans-section{padding:16px 14px 40px}

  /* TICKER */
  .ticker-track{animation-duration:500s}

  /* FOOTER */
  .footer{padding:14px}

  /* FLASH */
  .flash-container{right:10px;left:10px;max-width:none;top:70px}

  /* AUTH */
  .auth-wrap{padding:20px 10px}
  .auth-card{padding:20px 16px;width:95%;max-width:95vw}
  .auth-logo img{height:70px}

  /* CHAT LAYOUT */
  .chat-layout{
    display:flex;flex-direction:column;
    min-height:calc(100dvh - 60px)
  }
  .sidebar{
    position:fixed;left:-280px;top:0;height:100%;width:260px;
    z-index:300;transition:left .3s ease;
    overflow-y:auto;padding-top:60px
  }
  .sidebar.open{left:0;box-shadow:4px 0 24px rgba(0,0,0,.7)}
  .sidebar-toggle-btn{display:flex}

  .chat-main{flex:1;height:calc(100dvh - 60px);min-height:0}
  .chat-input-area{
    padding:10px 12px;
    padding-bottom:max(10px,env(safe-area-inset-bottom))
  }
  #mode-chat .chat-input-area{left:0}
  .msg-bubble{max-width:86%}

  /* EXAM */
  .exam-wrap{height:calc(100dvh - 60px)}
  .exam-header-bar{margin:10px 12px 0}
  .exam-progress{padding:8px 12px 0}

  /* PROFESSOR */
  .prof-form{grid-template-columns:1fr}
  .prof-form .full{grid-column:span 1}
  .prof-output{margin:0 12px 16px}
  .prof-notice{margin:10px 12px 0}

  /* SETTINGS */
  .settings-page{padding:16px 14px}

}