/* ==========================================================================
   Website Tuyển sinh Sau Đại học - HVPGVN tại Hà Nội
   Quy chuẩn UI/UX theo Mục 8 BRD_CongTuyenSinh_HVPGVN_2026
   ========================================================================== */

:root {
  /* 8.1 Color palette */
  --bg: #FAF6EF;            /* Trắng kem (Beige) */
  --primary: #1B5E20;       /* Xanh lá đậm (Forest Green) */
  --secondary: #C59B27;     /* Vàng đồng */
  --text: #333333;          /* Xám đen (Dark Charcoal) */
  --accent: #D32F2F;        /* Đỏ đun (Crimson) - cảnh báo lỗi */
  --white: #FFFFFF;
  --footer-bg: #4A3728;     /* Nâu trầm */
  --footer-text: #FDF5E6;   /* Trắng ngà / Kem nhạt */
  --success-bg: #E8F5E9;
  --warn: #E65100;
  --warn-bg: #FFF3E0;
  --border: #D8D0C0;

  /* 8.2 Typography */
  --font-heading: 'Merriweather', Georgia, serif;
  --font-body: 'Roboto', Arial, sans-serif;

  /* 8.3 UI components */
  --control-h: 44px;        /* Chiều cao nút bấm & ô nhập */
  --radius: 4px;            /* Bo góc */
  --space: 8px;             /* Hệ lưới 8px */
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-body);
  font-size: 18px;              /* Body Text 18px Roboto Regular */
  font-weight: 400;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
}

img { max-width: 100%; }

.container {
  max-width: 1160px;
  margin: 0 auto;
  padding: 0 calc(var(--space) * 2);
}
.container-narrow { max-width: 760px; }

.text-center { text-align: center; }

/* ===== Typography hierarchy (8.2) ===== */
.h1 {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 36px;
  color: var(--primary);
  line-height: 1.3;
  margin-bottom: calc(var(--space) * 2);
}
.h2 {
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 28px;
  color: var(--secondary);
  line-height: 1.35;
  margin-bottom: calc(var(--space) * 3);
}
.h3 {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 22px;
  color: var(--primary);
  text-transform: uppercase;
  margin-bottom: calc(var(--space) * 3);
}

/* ===== Header / Menu bar ===== */
.site-header {
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: calc(var(--space) * 2);
  padding-top: var(--space);
  padding-bottom: var(--space);
}
.brand {
  display: flex;
  align-items: center;
  gap: calc(var(--space) * 1.5);
  text-decoration: none;
}
.brand-logo { width: 56px; height: 56px; object-fit: contain; }
.brand-text { display: flex; flex-direction: column; }
.brand-name-1 {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 20px;          /* Brand Name 1 */
  color: var(--primary);
  line-height: 1.25;
}
.brand-name-2 {
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 16px;          /* Brand Name 2 */
  color: var(--secondary);
  letter-spacing: 1px;
}
.site-nav {
  display: flex;
  align-items: center;
  gap: calc(var(--space) * 3);
}
.nav-link {
  font-family: var(--font-body);
  font-weight: 500;
  font-size: 16px;          /* Menu Text */
  text-transform: uppercase;
  color: var(--text);
  text-decoration: none;
  transition: color .2s;
}
.nav-link:hover { color: var(--secondary); }  /* Hover: vàng đồng */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 24px;
  color: var(--primary);
  cursor: pointer;
}

/* ===== Buttons (8.3) ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: var(--control-h);
  padding: 0 calc(var(--space) * 3);
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-family: var(--font-body);
  font-weight: 500;
  font-size: 16px;          /* Button 16px Roboto Medium in hoa */
  text-transform: uppercase;
  text-decoration: none;
  cursor: pointer;
  transition: background .2s, opacity .2s;
}
.btn-primary {
  background: var(--primary);
  color: var(--white);
}
.btn-primary:hover { background: #14471a; }
.btn-primary:disabled {
  background: #9E9E9E;
  cursor: not-allowed;
  opacity: .7;
}
.btn-lg { padding: 0 calc(var(--space) * 4); }

/* ===== Sections ===== */
.section { padding: calc(var(--space) * 8) 0; }
.section-alt { background: #F3EDE1; }

.hero { padding-top: calc(var(--space) * 6); }
.hero-actions {
  display: flex;
  justify-content: center;
  margin: calc(var(--space) * 3) 0 calc(var(--space) * 5);
}
.timeline-figure {
  margin: 0 0 calc(var(--space) * 6);
  text-align: center;
}
.timeline-figure img {
  border-radius: var(--radius);
  box-shadow: 0 4px 18px rgba(74, 55, 40, .12);
}

/* ===== Compare table ===== */
.table-wrap { overflow-x: auto; }
.compare-table {
  width: 100%;
  border-collapse: collapse;
  background: var(--white);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 2px 10px rgba(74, 55, 40, .08);
}
.compare-table th, .compare-table td {
  padding: calc(var(--space) * 1.5) calc(var(--space) * 2);
  text-align: left;
  border-bottom: 1px solid var(--border);
}
.compare-table thead th {
  background: var(--primary);
  color: var(--white);
  font-family: var(--font-heading);
  font-size: 18px;
}
.compare-table tbody tr td:first-child { font-weight: 500; }
.compare-table tbody tr:nth-child(even) { background: #FBF8F2; }

/* ===== Steps ===== */
.steps-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: calc(var(--space) * 3);
  margin-bottom: calc(var(--space) * 8);
}
.step-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: calc(var(--space) * 3);
  box-shadow: 0 2px 8px rgba(74, 55, 40, .06);
}
.step-badge {
  width: 48px; height: 48px;
  display: flex; align-items: center; justify-content: center;
  background: var(--primary);
  color: var(--white);
  border-radius: 50%;
  font-size: 20px;
  margin-bottom: calc(var(--space) * 2);
}
.step-title {
  font-family: var(--font-heading);
  font-size: 19px;
  color: var(--primary);
  margin-bottom: var(--space);
}

/* ===== FAQ accordion ===== */
.faq-heading { margin-top: calc(var(--space) * 2); }
.faq-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: calc(var(--space) * 3);
  align-items: start;
}
.faq-col { display: flex; flex-direction: column; gap: calc(var(--space) * 2); }
.faq-item {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}
.faq-item summary {
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space);
  padding: calc(var(--space) * 2);
  font-weight: 500;
  cursor: pointer;
  color: var(--text);
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-icon::before {
  content: '+';
  font-size: 24px;
  font-weight: 500;
  color: var(--secondary);
  line-height: 1;
}
.faq-item[open] .faq-icon::before { content: '\2212'; }
.faq-item[open] summary { color: var(--primary); }
.faq-answer {
  padding: 0 calc(var(--space) * 2) calc(var(--space) * 2);
  border-top: 1px dashed var(--border);
  padding-top: calc(var(--space) * 1.5);
}
.faq-answer p + p, .faq-answer p + ul, .faq-answer ul + p { margin-top: var(--space); }
.faq-answer ul, .faq-answer ol { padding-left: calc(var(--space) * 3); }
.faq-answer li + li { margin-top: calc(var(--space) / 2); }

/* ===== Form card & tabs ===== */
.form-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: 0 4px 16px rgba(74, 55, 40, .08);
  overflow: hidden;
}
.tabs { display: flex; }
.tab-btn {
  flex: 1;
  height: calc(var(--control-h) + 8px);
  border: none;
  background: #E8E0D0;
  color: var(--text);
  font-family: var(--font-body);
  font-weight: 500;
  font-size: 16px;          /* Tab 16px Roboto Medium in hoa */
  text-transform: uppercase;
  cursor: pointer;
  transition: background .2s, color .2s;
}
.tab-btn.active {
  background: var(--primary);
  color: var(--white);
}
.tab-btn:not(.active):hover { color: var(--secondary); }

.reg-form { display: none; padding: calc(var(--space) * 4); }
.reg-form.active { display: block; }

.form-section-title {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 20px;
  color: var(--primary);
  text-transform: uppercase;
  margin: calc(var(--space) * 3) 0 calc(var(--space) * 2);
  padding-bottom: var(--space);
  border-bottom: 2px solid var(--secondary);
}
.reg-form .form-section-title:first-child { margin-top: 0; }
.form-sub-title {
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 18px;
  color: var(--secondary);
  margin: calc(var(--space) * 3) 0 calc(var(--space) * 2);
}

/* ===== Fields (8.3: input 44px, radius 4px, border 1px) ===== */
.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0 calc(var(--space) * 3);
}
.grid-2.nested { gap: 0 calc(var(--space) * 2); }
.field { margin-bottom: calc(var(--space) * 2); }
.field label, .field .label {
  display: block;
  font-size: 16px;
  font-weight: 500;
  margin-bottom: calc(var(--space) / 2);
}
.req { color: var(--accent); }
.field input[type="text"],
.field input[type="tel"],
.field input[type="email"] {
  width: 100%;
  height: var(--control-h);
  padding: 0 calc(var(--space) * 1.5);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-family: var(--font-body);
  font-size: 18px;          /* chữ người dùng gõ vào form */
  color: var(--text);
  background: var(--white);
  outline: none;
  transition: border-color .2s;
}
.field input::placeholder { color: #9E9E9E; font-size: 16px; }
.field input:focus { border-color: var(--primary); }        /* Focus: viền xanh lá */
.field input.invalid { border-color: var(--accent); }       /* Lỗi: viền đỏ đun */

.error-msg {
  display: none;
  color: var(--accent);
  font-size: 14px;
  margin-top: calc(var(--space) / 2);
}
.field input.invalid ~ .error-msg { display: block; }

/* ===== Radio & branch ===== */
.radio-row {
  display: flex;
  flex-wrap: wrap;
  gap: calc(var(--space) * 4);
  padding: var(--space) 0;
}
.radio-row.radio-col { flex-direction: column; gap: var(--space); }
.radio {
  display: flex;
  align-items: center;
  gap: var(--space);
  font-size: 17px;
  cursor: pointer;
}
.radio input { width: 20px; height: 20px; accent-color: var(--primary); cursor: pointer; }

.branch {
  border-left: 3px solid var(--secondary);
  padding: calc(var(--space) * 2) 0 0 calc(var(--space) * 2);
  margin-bottom: calc(var(--space) * 2);
}

/* ===== Alerts (BR-02) ===== */
.alert {
  border-radius: var(--radius);
  padding: calc(var(--space) * 1.5) calc(var(--space) * 2);
  font-size: 16px;
  margin-top: var(--space);
}
.alert-success { background: var(--success-bg); color: var(--primary); border: 1px solid var(--primary); }
.alert-warn { background: var(--warn-bg); color: var(--warn); border: 1px solid var(--warn); }

/* ===== Upload (BR-03) ===== */
.upload-intro { font-size: 16px; margin-bottom: calc(var(--space) * 2); }
.upload-intro em { color: #6b6b6b; }
.upload-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: calc(var(--space) * 2) calc(var(--space) * 3);
}
.upload-field { min-width: 0; }
.btn-upload {
  width: 100%;
  height: auto;
  min-height: var(--control-h);
  padding: var(--space) calc(var(--space) * 2);
  background: var(--white);
  border: 1px dashed var(--primary);
  color: var(--primary);
  text-transform: none;
  font-size: 15px;
  font-weight: 500;
  gap: var(--space);
  text-align: left;
  justify-content: flex-start;
}
.btn-upload:hover { background: var(--success-bg); }
.btn-upload.has-file { border-style: solid; background: var(--success-bg); }
.btn-upload-optional { border-color: #8D8D8D; color: #555; }
.btn-upload-optional:hover { background: #F5F5F5; }
.file-name {
  display: block;
  font-size: 14px;
  color: var(--primary);
  margin-top: calc(var(--space) / 2);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.upload-hint {
  font-size: 14px;
  color: #6b6b6b;
  margin-top: calc(var(--space) / 2);
}
.upload-note {
  background: var(--warn-bg);
  border-left: 3px solid var(--secondary);
  border-radius: var(--radius);
  font-size: 15px;
  padding: var(--space) calc(var(--space) * 1.5);
  margin: var(--space) 0;
}

/* ===== Commit & submit (BR-04) ===== */
.commit-box {
  margin-top: calc(var(--space) * 4);
  background: #FBF8F2;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: calc(var(--space) * 2);
}
.checkbox {
  display: flex;
  align-items: flex-start;
  gap: calc(var(--space) * 1.5);
  cursor: pointer;
  font-size: 16px;
}
.checkbox input {
  width: 22px; height: 22px;
  flex-shrink: 0;
  margin-top: 2px;
  accent-color: var(--primary);
  cursor: pointer;
}
.submit-row {
  display: flex;
  justify-content: center;
  margin-top: calc(var(--space) * 3);
}

/* ===== Lookup (Section 4) ===== */
.lookup-form {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: calc(var(--space) * 3);
  box-shadow: 0 2px 10px rgba(74, 55, 40, .06);
}
.lookup-form .btn { width: 100%; margin-top: var(--space); }
#lookupError { margin-top: calc(var(--space) * 1.5); }
#lookupError.show { display: block; }

.lookup-result {
  margin-top: calc(var(--space) * 4);
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: calc(var(--space) * 3);
}
.stepper {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: calc(var(--space) * 1.5);
  margin-top: calc(var(--space) * 2);
}
.step { text-align: center; position: relative; opacity: .45; }
.step.active, .step.done { opacity: 1; }
.step-dot {
  width: 48px; height: 48px;
  margin: 0 auto calc(var(--space));
  display: flex; align-items: center; justify-content: center;
  border-radius: 50%;
  background: #E0E0E0;
  color: #757575;
  font-size: 18px;
  position: relative;
  z-index: 1;
}
.step::before {
  content: '';
  position: absolute;
  top: 24px;
  left: calc(-50% + 24px);
  width: calc(100% - 48px);
  height: 3px;
  background: #E0E0E0;
}
.step:first-child::before { display: none; }
.step.done .step-dot, .step.active .step-dot { background: var(--primary); color: var(--white); }
.step.done::before, .step.active::before { background: var(--primary); }
.step-warn.active .step-dot { background: var(--warn); }   /* Cần bổ sung: màu cam */
.step-ok.active .step-dot { background: var(--primary); }  /* Hợp lệ: màu xanh */
.step-label { font-weight: 500; font-size: 15px; }
.step-desc { font-size: 13px; color: #757575; }

/* ===== Notice (Section 5) ===== */
.notice-box {
  display: flex;
  align-items: flex-start;
  gap: calc(var(--space) * 2);
  background: var(--warn-bg);
  border: 1px solid var(--secondary);
  border-radius: var(--radius);
  padding: calc(var(--space) * 3);
}
.notice-icon { font-size: 28px; color: var(--secondary); margin-top: 4px; }

/* ===== Footer ===== */
.site-footer {
  background: var(--footer-bg);
  color: var(--footer-text);
  padding: calc(var(--space) * 6) 0;
  margin-top: calc(var(--space) * 4);
}
.footer-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: calc(var(--space) * 4);
}
.footer-logo { width: 84px; margin-bottom: calc(var(--space) * 1.5); }
.footer-brand {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 17px;
  margin-bottom: 2px;
}
.footer-sub {
  font-family: var(--font-heading);
  font-size: 14px;
  color: var(--secondary);
  letter-spacing: 1px;
  margin-bottom: calc(var(--space) * 1.5);
}
.footer-copy { font-size: 14px; opacity: .85; }
.footer-title {
  font-family: var(--font-heading);
  font-size: 18px;
  color: var(--secondary);
  margin-bottom: calc(var(--space) * 2);
}
.footer-col p {
  font-size: 15px;
  margin-bottom: var(--space);
  display: flex;
  gap: var(--space);
  align-items: baseline;
}
.footer-col a { color: var(--footer-text); }
.footer-col i { color: var(--secondary); width: 18px; flex-shrink: 0; }

/* ===== Modal ===== */
.modal-overlay[hidden] { display: none; }
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, .55);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: calc(var(--space) * 2);
}
.modal {
  background: var(--white);
  border-radius: var(--radius);
  max-width: 520px;
  width: 100%;
  padding: calc(var(--space) * 5) calc(var(--space) * 4);
  text-align: center;
  box-shadow: 0 12px 40px rgba(0, 0, 0, .25);
}
.modal-icon { font-size: 56px; color: var(--primary); margin-bottom: calc(var(--space) * 2); }
.modal-title {
  font-family: var(--font-heading);
  font-size: 26px;
  color: var(--primary);
  margin-bottom: calc(var(--space) * 2);
}
.modal-body { margin-bottom: calc(var(--space) * 3); }
.modal-body strong { color: var(--primary); }

/* ===== Responsive ===== */
@media (max-width: 900px) {
  .h1 { font-size: 30px; }
  .h2 { font-size: 24px; }
  .steps-grid { grid-template-columns: 1fr; }
  .faq-grid { grid-template-columns: 1fr; }
  .upload-grid { grid-template-columns: 1fr; }
  .grid-2 { grid-template-columns: 1fr; }
  .grid-2.nested { grid-template-columns: 1fr 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .stepper { grid-template-columns: repeat(2, 1fr); gap: calc(var(--space) * 3) var(--space); }
  .step::before { display: none; }

  .nav-toggle { display: block; }
  .site-nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0; right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    padding: calc(var(--space) * 2);
    gap: calc(var(--space) * 2);
  }
  .site-nav.open { display: flex; }
  .brand-name-1 { font-size: 16px; }
  .brand-name-2 { font-size: 13px; }
}

@media (max-width: 480px) {
  .h1 { font-size: 26px; }
  .section { padding: calc(var(--space) * 5) 0; }
  .reg-form { padding: calc(var(--space) * 2); }
  .tab-btn { font-size: 13px; }
}