/* ===== YourHomework — giao diện khớp yourhomework.net (brand #0a8fdc, Be Vietnam Pro, Ant Design) ===== */
@import url('https://fonts.googleapis.com/css2?family=Be+Vietnam+Pro:wght@400;500;600;700;800&family=Quicksand:wght@500;600;700&display=swap');
:root{
  --primary:#0a8fdc; --primary-d:#006db5; --primary-h:#31abe8;
  --primary-l:#e6f7ff; --primary-l2:#f0faff; --primary-border:#87dfff;
  --green:#52c41a; --green-l:#f6ffed; --green-b:#b7eb8f;
  --red:#ff4d4f; --red-l:#fff2f0; --red-b:#ffccc7;
  --amber:#faad14; --amber-l:#fffbe6;
  --bg:#f5f7fa; --card:#fff;
  --line:#f0f0f0; --line2:#d9d9d9;
  --text:rgba(0,0,0,.88); --muted:rgba(0,0,0,.45); --muted2:rgba(0,0,0,.65);
  --radius:8px; --radius-lg:12px;
  --shadow:0 1px 2px rgba(0,0,0,.03),0 1px 6px -1px rgba(0,0,0,.02),0 2px 4px rgba(0,0,0,.02);
  --shadow-lg:0 6px 16px 0 rgba(0,0,0,.08),0 3px 6px -4px rgba(0,0,0,.12);
}
*{box-sizing:border-box}
body{margin:0;font-family:'Be Vietnam Pro',-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;background:var(--bg);color:var(--text);font-size:14px;line-height:1.5715}
a{color:var(--primary);text-decoration:none}
a:hover{color:var(--primary-h);text-decoration:none}
h1,h2,h3{margin:0 0 .4em;color:var(--text);font-weight:700}

/* layout */
.app-shell{display:flex;min-height:100vh}
.sidebar{width:248px;background:#fff;border-right:1px solid var(--line);display:flex;flex-direction:column;position:fixed;top:0;bottom:0;left:0;z-index:40}
.brand{display:flex;align-items:center;gap:8px;padding:14px 18px;height:64px}
.brand:hover{text-decoration:none}
.brand img{height:30px;width:auto;display:block}
.brand-mark{background:var(--primary);color:#fff;width:34px;height:34px;border-radius:8px;display:grid;place-items:center;font-size:14px;font-weight:800;font-family:'Quicksand',sans-serif}
.brand-text{font-family:'Quicksand',sans-serif;font-weight:700;font-size:20px;color:var(--primary)}
.nav{flex:1;overflow-y:auto;padding:6px 8px}
.nav::-webkit-scrollbar{width:6px}.nav::-webkit-scrollbar-thumb{background:#e0e0e0;border-radius:3px}
.nav-group{font-size:11px;text-transform:uppercase;letter-spacing:.04em;color:var(--muted);margin:14px 12px 4px;font-weight:700}
.nav-item{display:flex;align-items:center;gap:10px;padding:9px 12px;border-radius:8px;color:var(--muted2);font-weight:500;margin-bottom:2px;transition:all .15s}
.nav-item:hover{background:var(--primary-l2);color:var(--primary);text-decoration:none}
.nav-item.active{background:var(--primary-l);color:var(--primary);font-weight:600}
.nav-item .ico{width:18px;height:18px;display:inline-flex;flex:none}
.nav-item .ico svg{width:18px;height:18px}
.sidebar-foot{border-top:1px solid var(--line);padding:8px}

.main{flex:1;margin-left:248px;display:flex;flex-direction:column;min-width:0}
.topbar{height:64px;background:#fff;border-bottom:1px solid var(--line);display:flex;align-items:center;gap:14px;padding:0 24px;position:sticky;top:0;z-index:30}
.topbar-title{font-weight:600;font-size:16px}
.topbar-right{margin-left:auto;display:flex;align-items:center;gap:14px}
.hamb{display:none;border:0;background:none;font-size:20px;cursor:pointer;color:var(--muted2)}
.user-chip{display:flex;align-items:center;gap:8px;color:var(--text)}
.user-chip:hover{text-decoration:none;color:var(--text)}
.avatar{width:32px;height:32px;border-radius:50%;background:var(--primary);color:#fff;display:grid;place-items:center;font-weight:600;font-size:14px}
.uname{font-weight:600;font-size:14px}
.content{padding:24px;max-width:1240px;width:100%}

/* badges */
.badge{font-size:12px;font-weight:600;padding:1px 9px;border-radius:4px;border:1px solid transparent;line-height:20px;display:inline-block}
.badge-admin{background:var(--red-l);color:var(--red);border-color:var(--red-b)}
.badge-teacher{background:var(--primary-l);color:var(--primary-d);border-color:var(--primary-border)}
.badge-student{background:var(--green-l);color:var(--green);border-color:var(--green-b)}
.pill{display:inline-block;font-size:12px;font-weight:500;padding:1px 8px;border-radius:4px;background:#fafafa;color:var(--muted2);border:1px solid var(--line)}

/* cards / grid */
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius-lg);box-shadow:var(--shadow)}
.card-pad{padding:20px}
.grid{display:grid;gap:16px}
.grid-2{grid-template-columns:repeat(2,1fr)}
.grid-3{grid-template-columns:repeat(3,1fr)}
.grid-4{grid-template-columns:repeat(4,1fr)}
.page-head{display:flex;align-items:center;gap:12px;margin-bottom:20px}
.page-head h1{font-size:20px;margin:0;font-weight:700}
.page-head .spacer{flex:1}
.muted{color:var(--muted)}
.small{font-size:13px}

/* stat */
.stat{padding:20px;border-radius:var(--radius-lg);background:#fff;border:1px solid var(--line);box-shadow:var(--shadow)}
.stat .num{font-size:30px;font-weight:700;color:var(--text)}
.stat .lbl{color:var(--muted);font-size:13px;margin-top:2px}
.stat .ico{float:right;font-size:24px;opacity:.9;color:var(--primary)}

/* buttons (antd style) */
.btn{display:inline-flex;align-items:center;gap:7px;border:1px solid var(--primary);background:var(--primary);color:#fff;padding:7px 16px;border-radius:6px;font-weight:500;cursor:pointer;font-size:14px;font-family:inherit;transition:all .15s;box-shadow:0 2px 0 rgba(5,145,255,.06)}
.btn:hover{background:var(--primary-h);border-color:var(--primary-h);text-decoration:none;color:#fff}
.btn-ghost{background:#fff;color:var(--text);border-color:var(--line2)}
.btn-ghost:hover{background:#fff;color:var(--primary);border-color:var(--primary)}
.btn-danger{background:var(--red);border-color:var(--red)}.btn-danger:hover{background:#ff7875;border-color:#ff7875}
.btn-success{background:var(--green);border-color:var(--green)}.btn-success:hover{background:#73d13d;border-color:#73d13d}
.btn-sm{padding:3px 11px;font-size:13px;border-radius:6px}
.btn-block{width:100%;justify-content:center}

/* tables */
.table{width:100%;border-collapse:collapse;background:#fff;border-radius:var(--radius-lg);overflow:hidden;box-shadow:var(--shadow);border:1px solid var(--line)}
.table th,.table td{padding:12px 16px;text-align:left;border-bottom:1px solid var(--line)}
.table th{background:#fafafa;font-size:13px;font-weight:600;color:var(--muted2)}
.table tr:last-child td{border-bottom:0}
.table tbody tr:hover td{background:var(--primary-l2)}

/* forms */
.form-row{margin-bottom:16px}
.form-row label{display:block;font-weight:500;font-size:14px;margin-bottom:6px;color:var(--text)}
.input,.select,.textarea{width:100%;padding:7px 11px;border:1px solid var(--line2);border-radius:6px;font-size:14px;font-family:inherit;background:#fff;transition:all .15s;color:var(--text)}
.input:focus,.select:focus,.textarea:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 2px rgba(10,143,220,.1)}
.textarea{min-height:84px;resize:vertical}
.row{display:flex;gap:12px}.row>*{flex:1}

/* alerts */
.alert{padding:9px 16px;border-radius:8px;margin-bottom:16px;font-weight:500;border:1px solid transparent}
.alert-info{background:var(--primary-l);color:var(--primary-d);border-color:var(--primary-border)}
.alert-success{background:var(--green-l);color:#389e0d;border-color:var(--green-b)}
.alert-warn{background:var(--amber-l);color:#d48806;border-color:#ffe58f}
.alert-error,.alert-danger{background:var(--red-l);color:var(--red);border-color:var(--red-b)}

/* auth pages */
.auth-wrap{min-height:100vh;display:grid;place-items:center;background:linear-gradient(135deg,#eafbe3 0%,#cfeebb 50%,#aee08e 100%);padding:20px}
.auth-card{background:#fff;border-radius:16px;padding:36px;width:100%;max-width:420px;box-shadow:var(--shadow-lg)}
.auth-card .brand{justify-content:center;padding:0 0 8px;height:auto}
.auth-sub{text-align:center;color:var(--muted);margin-bottom:24px}
.auth-alt{text-align:center;margin-top:18px;font-size:14px}

/* modal (antd style) */
.ym-mask{position:fixed;inset:0;background:rgba(0,0,0,.45);z-index:1000;display:none;align-items:flex-start;justify-content:center;overflow:auto;padding:60px 16px}
.ym-mask.open{display:flex}
.ym{background:#fff;border-radius:8px;width:100%;max-width:560px;box-shadow:var(--shadow-lg);animation:ymin .2s}
@keyframes ymin{from{transform:translateY(-12px);opacity:.6}to{transform:none;opacity:1}}
.ym-head{padding:16px 20px;border-bottom:1px solid var(--line);font-weight:600;font-size:16px;display:flex;align-items:center}
.ym-head .x{margin-left:auto;cursor:pointer;color:var(--muted);font-size:18px;border:0;background:none}
.ym-body{padding:20px;max-height:60vh;overflow:auto}
.ym-foot{padding:12px 20px;border-top:1px solid var(--line);display:flex;justify-content:flex-end;gap:8px}

/* section title (form mục) */
.sec-title{font-size:15px;font-weight:700;color:var(--primary-d);margin:0 0 14px;padding-bottom:8px;border-bottom:1px solid var(--line)}

/* tabs */
.tabs{display:flex;gap:4px;border-bottom:2px solid transparent}
.tab{border:0;background:none;padding:8px 16px;cursor:pointer;font-size:14px;font-weight:500;color:var(--muted2);font-family:inherit;border-bottom:2px solid transparent;margin-bottom:-15px}
.tab:hover{color:var(--primary)}
.tab.active{color:var(--primary);border-bottom-color:var(--primary)}

/* empty state */
.empty{text-align:center;padding:48px 20px;color:var(--muted)}
.empty .big{font-size:40px;margin-bottom:8px}

/* flashcard */
.flash-stage{max-width:600px;margin:0 auto}
.flashcard{perspective:1400px;height:320px;cursor:pointer}
.flashcard-inner{position:relative;width:100%;height:100%;transition:transform .5s;transform-style:preserve-3d}
.flashcard.flip .flashcard-inner{transform:rotateY(180deg)}
.flash-face{position:absolute;inset:0;backface-visibility:hidden;border-radius:16px;display:grid;place-items:center;text-align:center;padding:24px;box-shadow:var(--shadow-lg);border:1px solid var(--line);background:#fff}
.flash-face .big{font-size:38px;font-weight:700;color:var(--text)}
.flash-face .ph{color:var(--muted);margin-top:8px}
.flash-back{transform:rotateY(180deg);background:var(--primary-l)}
.flash-controls{display:flex;justify-content:center;gap:12px;margin-top:20px;align-items:center}

/* quiz / test */
.q-card{background:#fff;border:1px solid var(--line);border-radius:var(--radius-lg);padding:20px;margin-bottom:16px;box-shadow:var(--shadow)}
.q-head{display:flex;gap:10px;margin-bottom:12px}
.q-num{background:var(--primary);color:#fff;width:28px;height:28px;border-radius:8px;display:grid;place-items:center;font-weight:600;flex:none}
.opt{display:flex;align-items:center;gap:10px;padding:10px 14px;border:1px solid var(--line2);border-radius:8px;margin-bottom:8px;cursor:pointer;transition:all .15s}
.opt:hover{background:var(--primary-l2);border-color:var(--primary-border)}
.opt input{width:16px;height:16px;accent-color:var(--primary)}
.opt.correct{background:var(--green-l);border-color:var(--green-b)}
.opt.wrong{background:var(--red-l);border-color:var(--red-b)}
.result-score{text-align:center;padding:30px}
.result-score .big{font-size:54px;font-weight:800;color:var(--primary)}

/* rich text editor (bài đọc) */
.rt-wrap{border:1px solid var(--line2);border-radius:10px;overflow:hidden}
.rt-tools{display:flex;flex-wrap:wrap;gap:2px;background:#fafbff;border-bottom:1px solid var(--line);padding:6px}
.rt-tools button{border:1px solid var(--line);background:#fff;border-radius:6px;padding:4px 9px;cursor:pointer;font-size:13px}
.rt-tools button:hover{border-color:var(--primary);color:var(--primary)}
.rt-ed{min-height:280px;max-height:520px;overflow:auto;padding:14px 16px;outline:none;font-size:15px;line-height:1.7;border:2px solid var(--line2);border-top:0;background:#fff}
.rt-ed:focus{border-color:var(--primary);box-shadow:inset 0 0 0 1px var(--primary)}
.rt-wrap{border:0}
.rt-tools{border:2px solid var(--line2);border-bottom:0;border-radius:10px 10px 0 0}
.rt-ed img{max-width:100%}
.rt-ed iframe{max-width:100%}

/* question type bar */
.qtype-bar{display:flex;flex-wrap:wrap;gap:8px}
.qtbtn{border:1px solid var(--line2);background:#fff;color:var(--text);padding:7px 14px;border-radius:6px;font-size:13px;font-weight:500;cursor:pointer;font-family:inherit;transition:all .15s}
.qtbtn:hover{border-color:var(--primary);color:var(--primary);background:var(--primary-l2)}

/* question builder */
.qb-item{border:1px solid var(--line);border-radius:var(--radius-lg);padding:16px;margin-bottom:14px;background:#fff;box-shadow:var(--shadow)}
.qb-card-head{display:flex;align-items:center;gap:6px;flex-wrap:wrap;padding-bottom:10px;border-bottom:1px solid var(--line)}
.qb-cau{color:var(--primary-d)}
.qb-item .qb-head{display:flex;gap:10px;align-items:center;margin-bottom:12px}
.opt-row{display:flex;gap:8px;align-items:center;margin-bottom:6px}
.opt-row input[type=text]{flex:1}
.match-row{display:flex;gap:8px;margin-bottom:6px}

/* landing */
.hero{background:linear-gradient(135deg,#0a8fdc 0%,#31abe8 60%,#87dfff 100%);color:#fff;padding:84px 20px;text-align:center}
.hero h1{font-size:42px;margin-bottom:14px;color:#fff;font-weight:800}
.hero p{font-size:18px;opacity:.96;max-width:640px;margin:0 auto 28px}
.hero .btn-ghost{background:rgba(255,255,255,.16);color:#fff;border-color:rgba(255,255,255,.5)}
.hero .btn-ghost:hover{background:rgba(255,255,255,.26);color:#fff}
.landing-nav{display:flex;align-items:center;padding:14px 28px;gap:12px;background:#fff;border-bottom:1px solid var(--line)}
.landing-nav .brand{padding:0;height:auto}
.feature-sec{max-width:1080px;margin:60px auto;padding:0 20px}
.feature-sec .card-pad>div:first-child{color:var(--primary)}

@media(max-width:860px){
  .grid-3,.grid-4{grid-template-columns:repeat(2,1fr)}
  .sidebar{transform:translateX(-100%);transition:.25s}
  .sidebar.open{transform:none}
  .main{margin-left:0}
  .hero h1{font-size:32px}
}
@media(max-width:560px){.grid-2,.grid-3,.grid-4{grid-template-columns:1fr}.row{flex-direction:column}}
/* ===== Tối ưu mobile bổ sung (PWA, 2026-06-17) ===== */
@media(max-width:860px){
  /* Bảng dài -> cuộn ngang trên điện thoại, không vỡ layout */
  .main table{display:block;overflow-x:auto;max-width:100%;-webkit-overflow-scrolling:touch}
}
@media(max-width:480px){
  .main{padding:14px 12px}
  h2{font-size:20px}
  .topbar-title{font-size:15px}
  .stat .num{font-size:24px}
  .btn{padding:10px 15px}
  /* Nút/ô chạm tối thiểu 42px cho dễ bấm */
  .btn,.input,.select,input[type=text],input[type=password]{min-height:42px}
}