/* ============================================================
   FDU.email — Premium Registration UI
   ============================================================ */

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

:root {
  /* ── 调色板 ── */
  --c-bg: #07060e;
  --c-surface: rgba(255,255,255,.035);
  --c-surface-hover: rgba(255,255,255,.06);
  --c-border: rgba(255,255,255,.07);
  --c-border-active: rgba(129,140,248,.45);
  --c-text: #eef0f6;
  --c-text-2: #a1a8c0;
  --c-text-3: #5e6580;
  --c-primary: #818cf8;
  --c-primary-vivid: #6366f1;
  --c-accent: #c084fc;
  --c-success: #34d399;
  --c-error: #f87171;
  --c-warning: #fbbf24;
  /* ── 尺寸 ── */
  --radius: 18px;
  --radius-sm: 12px;
  --radius-xs: 8px;
}

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  background: var(--c-bg);
  color: var(--c-text);
  min-height: 100vh;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ================================================================
   背景效果
   ================================================================ */

.bg-canvas {
  position: fixed; inset: 0; z-index: 0; pointer-events: none;
}

.mesh-gradient {
  position: absolute; inset: 0;
  background:
    radial-gradient(ellipse 80% 60% at 20% 10%, rgba(99,102,241,.18) 0%, transparent 60%),
    radial-gradient(ellipse 60% 80% at 80% 90%, rgba(168,85,247,.14) 0%, transparent 55%),
    radial-gradient(ellipse 50% 40% at 55% 45%, rgba(56,189,248,.08) 0%, transparent 50%);
  animation: meshShift 25s ease-in-out infinite alternate;
}

@keyframes meshShift {
  0%   { filter: hue-rotate(0deg) brightness(1); }
  50%  { filter: hue-rotate(15deg) brightness(1.1); }
  100% { filter: hue-rotate(-10deg) brightness(0.95); }
}

.grid-overlay {
  position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,.02) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,.02) 1px, transparent 1px);
  background-size: 60px 60px;
  mask-image: radial-gradient(ellipse 70% 50% at 50% 30%, black 30%, transparent 70%);
  -webkit-mask-image: radial-gradient(ellipse 70% 50% at 50% 30%, black 30%, transparent 70%);
}

#particles {
  position: absolute; inset: 0; width: 100%; height: 100%;
}

/* ================================================================
   布局
   ================================================================ */

.page-wrapper {
  position: relative; z-index: 1;
  display: flex; flex-direction: column;
  min-height: 100vh;
}

.main-content {
  flex: 1;
  max-width: 540px;
  width: 100%;
  margin: 0 auto;
  padding: 0 20px;
}

/* ================================================================
   导航栏
   ================================================================ */

.navbar {
  display: flex; align-items: center; justify-content: space-between;
  max-width: 900px; width: 100%;
  margin: 0 auto;
  padding: 20px 24px;
}

.nav-logo {
  display: flex; align-items: center; gap: 10px;
}

.nav-logo-text {
  font-size: 18px; font-weight: 800;
  letter-spacing: -.3px;
  color: var(--c-text);
}

.nav-logo-text .dot {
  color: var(--c-accent);
}

.nav-link {
  display: flex; align-items: center; gap: 6px;
  font-size: 13px; font-weight: 500;
  color: var(--c-text-3);
  text-decoration: none;
  padding: 6px 14px;
  border-radius: 8px;
  border: 1px solid var(--c-border);
  transition: all .25s;
}

.nav-link:hover {
  color: var(--c-text-2);
  border-color: rgba(255,255,255,.15);
  background: var(--c-surface);
}

/* ================================================================
   Hero
   ================================================================ */

.hero {
  text-align: center;
  padding: 60px 0 40px;
  animation: fadeUp .7s ease-out;
}

.hero-badge {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 5px 14px 5px 8px;
  border-radius: 100px;
  background: rgba(34,197,94,.08);
  border: 1px solid rgba(34,197,94,.18);
  font-size: 12px; font-weight: 600;
  color: var(--c-success);
  margin-bottom: 24px;
}

.hero-title {
  font-size: clamp(32px, 6vw, 48px);
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -1.5px;
  margin-bottom: 18px;
}

.gradient-text {
  background: linear-gradient(135deg, #818cf8 0%, #c084fc 40%, #f0abfc 100%);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-desc {
  font-size: 16px; line-height: 1.7;
  color: var(--c-text-2);
  max-width: 420px; margin: 0 auto;
}

.inline-code {
  font-family: 'JetBrains Mono', monospace;
  font-size: 14px; font-weight: 500;
  padding: 2px 8px;
  border-radius: 6px;
  background: rgba(129,140,248,.12);
  color: var(--c-primary);
  border: 1px solid rgba(129,140,248,.15);
}

/* ================================================================
   步骤指示器
   ================================================================ */

.stepper {
  display: flex; align-items: center; justify-content: center;
  gap: 0; margin-bottom: 24px;
  animation: fadeUp .7s ease-out .1s both;
}

.step-item {
  display: flex; align-items: center; gap: 8px;
  opacity: .3;
  transition: opacity .4s, transform .3s;
}

.step-item.active { opacity: 1; }
.step-item.done   { opacity: .65; }

.step-num {
  width: 30px; height: 30px;
  border-radius: 50%;
  display: grid; place-items: center;
  font-size: 12px; font-weight: 700;
  background: var(--c-surface);
  border: 1.5px solid var(--c-border);
  position: relative;
  transition: all .4s;
}

.step-check { display: none; }

.step-item.active .step-num {
  background: linear-gradient(135deg, var(--c-primary-vivid), var(--c-accent));
  border-color: transparent;
  color: #fff;
  box-shadow: 0 0 18px rgba(99,102,241,.45), 0 0 4px rgba(99,102,241,.3);
}

.step-item.done .step-num {
  background: var(--c-success);
  border-color: transparent;
  color: #fff;
}

.step-item.done .step-digit { display: none; }
.step-item.done .step-check { display: block; }

.step-text {
  font-size: 12px; font-weight: 600;
  color: var(--c-text-3);
  letter-spacing: .3px;
}

.step-item.active .step-text { color: var(--c-text); }

.step-connector {
  width: 48px; height: 2px;
  background: var(--c-border);
  border-radius: 1px;
  margin: 0 6px;
  overflow: hidden;
}

.step-connector-fill {
  width: 0; height: 100%;
  background: var(--c-primary);
  border-radius: 1px;
  transition: width .5s ease;
}

/* ================================================================
   卡片
   ================================================================ */

.card {
  position: relative;
  border-radius: var(--radius);
  overflow: hidden;
  transition: transform .35s, opacity .35s;
}

.card-glow {
  position: absolute; inset: 0;
  border-radius: var(--radius);
  padding: 1px;
  background: linear-gradient(135deg, rgba(129,140,248,.25), rgba(192,132,252,.15), rgba(255,255,255,.05));
  -webkit-mask: linear-gradient(#fff,#fff) content-box, linear-gradient(#fff,#fff);
  mask: linear-gradient(#fff,#fff) content-box, linear-gradient(#fff,#fff);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
}

.success-glow {
  background: linear-gradient(135deg, rgba(34,197,94,.3), rgba(16,185,129,.2), rgba(255,255,255,.05));
}

.card-inner {
  background: rgba(12,11,25,.75);
  backdrop-filter: blur(40px) saturate(1.3);
  -webkit-backdrop-filter: blur(40px) saturate(1.3);
  padding: 36px 32px;
  border-radius: var(--radius);
}

.step-card {
  display: none;
}

.step-card.visible {
  display: block;
  animation: cardIn .5s ease-out;
}

@keyframes cardIn {
  from { opacity: 0; transform: translateY(14px) scale(.98); }
  to   { opacity: 1; transform: none; }
}

.card-head {
  text-align: center; margin-bottom: 28px;
}

.icon-circle {
  width: 52px; height: 52px;
  border-radius: 16px;
  display: grid; place-items: center;
  margin: 0 auto 16px;
  background: linear-gradient(135deg, rgba(129,140,248,.15), rgba(192,132,252,.08));
  border: 1px solid rgba(129,140,248,.2);
  color: var(--c-primary);
  transition: transform .3s;
}

.icon-circle.accent {
  background: linear-gradient(135deg, rgba(192,132,252,.15), rgba(244,114,182,.08));
  border-color: rgba(192,132,252,.2);
  color: var(--c-accent);
}

.icon-circle.success {
  background: linear-gradient(135deg, rgba(52,211,153,.15), rgba(16,185,129,.08));
  border-color: rgba(52,211,153,.2);
  color: var(--c-success);
}

.card-head h2 {
  font-size: 20px; font-weight: 700;
  margin-bottom: 6px;
  letter-spacing: -.3px;
}

.card-head p {
  font-size: 14px; color: var(--c-text-3); line-height: 1.5;
}

.card-head strong {
  color: var(--c-primary); font-weight: 600;
  font-family: 'JetBrains Mono', monospace; font-size: 13px;
}

/* ================================================================
   表单元素
   ================================================================ */

.form-field {
  margin-bottom: 22px;
}

.form-field label {
  display: block;
  font-size: 11px; font-weight: 700;
  color: var(--c-text-2);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 8px;
}

.input-combo {
  display: flex; align-items: center;
  background: rgba(255,255,255,.03);
  border: 1.5px solid var(--c-border);
  border-radius: var(--radius-sm);
  transition: border-color .3s, box-shadow .3s;
  overflow: hidden;
}

.input-combo:focus-within {
  border-color: var(--c-border-active);
  box-shadow: 0 0 0 3px rgba(129,140,248,.12);
}

.input-icon {
  display: grid; place-items: center;
  padding: 0 0 0 14px;
  color: var(--c-text-3);
  flex-shrink: 0;
}

.input-combo input {
  flex: 1; min-width: 0;
  background: transparent; border: none; outline: none;
  padding: 14px 12px;
  font-size: 15px; font-family: inherit;
  color: var(--c-text);
}

.input-combo input::placeholder {
  color: var(--c-text-3);
}

.input-tag {
  padding: 14px 14px;
  font-size: 13px; font-weight: 500;
  color: var(--c-text-3);
  background: rgba(255,255,255,.025);
  border-left: 1px solid var(--c-border);
  white-space: nowrap;
  font-family: 'JetBrains Mono', monospace;
  letter-spacing: -.3px;
}

.field-note {
  display: block;
  font-size: 11px; color: var(--c-text-3);
  margin-top: 8px; line-height: 1.5;
}

/* ── 验证码格子 ── */

.code-grid {
  display: flex; align-items: center;
  justify-content: center; gap: 8px;
}

.code-cell {
  width: 48px; height: 56px;
  text-align: center;
  font-size: 22px; font-weight: 700;
  font-family: 'JetBrains Mono', monospace;
  background: rgba(255,255,255,.03);
  border: 1.5px solid var(--c-border);
  border-radius: var(--radius-xs);
  color: var(--c-text);
  outline: none;
  caret-color: var(--c-primary);
  transition: all .25s;
}

.code-cell:focus {
  border-color: var(--c-border-active);
  box-shadow: 0 0 0 3px rgba(129,140,248,.12);
  background: rgba(99,102,241,.05);
}

.code-cell.filled {
  border-color: var(--c-primary);
  background: rgba(99,102,241,.07);
  color: var(--c-primary);
}

.code-dash {
  font-size: 20px; color: var(--c-text-3);
  margin: 0 2px; user-select: none;
}

/* ── 别名反馈 ── */

.alias-feedback {
  min-height: 22px;
  margin-top: 8px;
  font-size: 13px; font-weight: 500;
  display: flex; align-items: center; gap: 6px;
}

.alias-feedback.ok      { color: var(--c-success); }
.alias-feedback.taken   { color: var(--c-error); }
.alias-feedback.loading { color: var(--c-text-3); }
.alias-feedback.invalid { color: var(--c-warning); }

/* ================================================================
   按钮
   ================================================================ */

.btn-main {
  display: flex; align-items: center; justify-content: center; gap: 8px;
  width: 100%;
  padding: 14px 24px;
  border: none; border-radius: var(--radius-sm);
  font-size: 15px; font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  background: linear-gradient(135deg, var(--c-primary-vivid), var(--c-accent));
  color: #fff;
  box-shadow: 0 4px 20px rgba(99,102,241,.3), inset 0 1px 0 rgba(255,255,255,.12);
  transition: all .3s;
  position: relative; overflow: hidden;
}

.btn-main::before {
  content: '';
  position: absolute; inset: 0;
  background: linear-gradient(135deg, transparent, rgba(255,255,255,.08));
  opacity: 0;
  transition: opacity .3s;
}

.btn-main:hover:not(:disabled)::before { opacity: 1; }

.btn-main:hover:not(:disabled) {
  transform: translateY(-1px);
  box-shadow: 0 8px 28px rgba(99,102,241,.4), inset 0 1px 0 rgba(255,255,255,.15);
}

.btn-main:active:not(:disabled) {
  transform: translateY(0);
  box-shadow: 0 2px 12px rgba(99,102,241,.3);
}

.btn-main:disabled {
  opacity: .4; cursor: not-allowed;
}

.btn-main.loading .btn-label,
.btn-main.loading .btn-arrow { display: none; }
.btn-main.loading .btn-spinner { display: block; }

.btn-spinner {
  display: none;
  width: 20px; height: 20px;
  border: 2.5px solid rgba(255,255,255,.25);
  border-top-color: #fff;
  border-radius: 50%;
  animation: spin .65s linear infinite;
}

.btn-arrow { flex-shrink: 0; transition: transform .25s; }
.btn-main:hover:not(:disabled) .btn-arrow { transform: translateX(3px); }

@keyframes spin { to { transform: rotate(360deg); } }

.card-actions {
  display: flex; justify-content: space-between; align-items: center;
  margin-top: 14px;
}

.link-btn {
  display: inline-flex; align-items: center; gap: 4px;
  background: none; border: none;
  color: var(--c-text-3); font-size: 13px; font-weight: 500;
  font-family: inherit; cursor: pointer;
  padding: 6px 2px;
  transition: color .25s;
}

.link-btn:hover:not(:disabled) { color: var(--c-primary); }
.link-btn:disabled { opacity: .35; cursor: not-allowed; }

/* ================================================================
   消息
   ================================================================ */

.msg {
  margin-top: 16px; min-height: 0;
  font-size: 13px; text-align: center;
  border-radius: var(--radius-xs);
  transition: all .3s;
  overflow: hidden;
}

.msg:empty { padding: 0; }

.msg.err {
  color: var(--c-error);
  background: rgba(248,113,113,.08);
  padding: 10px 14px;
  border: 1px solid rgba(248,113,113,.18);
}

.msg.ok {
  color: var(--c-success);
  background: rgba(52,211,153,.08);
  padding: 10px 14px;
  border: 1px solid rgba(52,211,153,.18);
}

/* ================================================================
   成功页
   ================================================================ */

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

.success-badge {
  margin: 0 auto 20px;
  animation: popIn .5s cubic-bezier(.175,.885,.32,1.275);
}

@keyframes popIn {
  0%   { transform: scale(0); opacity: 0; }
  60%  { transform: scale(1.15); }
  100% { transform: scale(1); opacity: 1; }
}

.success-title {
  font-size: 26px; font-weight: 800;
  background: linear-gradient(135deg, var(--c-success), #6ee7b7);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 16px;
}

.success-address {
  display: inline-block;
  font-family: 'JetBrains Mono', monospace;
  font-size: 20px; font-weight: 700;
  color: var(--c-primary);
  padding: 14px 28px;
  background: rgba(99,102,241,.08);
  border: 1.5px solid rgba(99,102,241,.2);
  border-radius: var(--radius-sm);
  margin-bottom: 8px;
  cursor: pointer;
  transition: all .25s;
  user-select: all;
}

.success-address:hover {
  background: rgba(99,102,241,.12);
  border-color: rgba(99,102,241,.35);
}

.success-hint {
  font-size: 13px; color: var(--c-text-3);
  margin-bottom: 28px;
}

.feature-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px;
  text-align: left;
}

.feature-card {
  padding: 18px 16px;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  transition: all .25s;
}

.feature-card:hover {
  background: var(--c-surface-hover);
  border-color: rgba(255,255,255,.12);
  transform: translateY(-2px);
}

.feature-icon {
  width: 36px; height: 36px;
  border-radius: 10px;
  display: grid; place-items: center;
  background: rgba(129,140,248,.1);
  color: var(--c-primary);
  margin-bottom: 12px;
}

.feature-card h3 {
  font-size: 13px; font-weight: 700;
  margin-bottom: 4px; color: var(--c-text);
}

.feature-card p {
  font-size: 12px; line-height: 1.5;
  color: var(--c-text-3);
}

/* ================================================================
   特性展示区
   ================================================================ */

.features-section {
  margin-top: 64px;
  padding: 0 0 40px;
  animation: fadeUp .7s ease-out .3s both;
  max-width: 720px;
  margin-left: auto;
  margin-right: auto;
}

.section-title {
  text-align: center;
  font-size: 20px; font-weight: 800;
  letter-spacing: -.3px;
  margin-bottom: 28px;
  color: var(--c-text);
}

.flow-cards {
  display: flex; align-items: stretch;
  gap: 0; justify-content: center;
  padding: 0 20px;
}

.flow-card {
  flex: 1;
  padding: 24px 20px;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  transition: all .25s;
}

.flow-card:hover {
  background: var(--c-surface-hover);
  border-color: rgba(255,255,255,.12);
  transform: translateY(-3px);
}

.flow-num {
  font-family: 'JetBrains Mono', monospace;
  font-size: 28px; font-weight: 700;
  background: linear-gradient(135deg, var(--c-primary), var(--c-accent));
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 10px;
}

.flow-card h3 {
  font-size: 15px; font-weight: 700;
  margin-bottom: 6px;
}

.flow-card p {
  font-size: 13px; color: var(--c-text-3); line-height: 1.6;
}

.flow-card code {
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px; padding: 1px 5px;
  background: rgba(129,140,248,.1);
  border-radius: 4px; color: var(--c-primary);
}

.flow-arrow {
  display: grid; place-items: center;
  color: var(--c-text-3); padding: 0 8px;
  flex-shrink: 0;
}

/* ================================================================
   底部
   ================================================================ */

.site-footer {
  padding: 24px 20px;
  text-align: center;
}

.footer-inner {
  font-size: 12px; color: var(--c-text-3);
  line-height: 1.6;
}

.footer-dot {
  margin: 0 6px; opacity: .4;
}

/* ================================================================
   动画
   ================================================================ */

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(18px); }
  to   { opacity: 1; transform: none; }
}

/* ================================================================
   响应式
   ================================================================ */

@media (max-width: 560px) {
  .hero { padding: 40px 0 28px; }
  .hero-title { font-size: 30px; letter-spacing: -1px; }
  .hero-desc { font-size: 14px; }

  .card-inner { padding: 28px 22px; }

  .code-cell { width: 42px; height: 50px; font-size: 19px; }
  .code-grid { gap: 6px; }
  .code-dash { margin: 0; }

  .step-text { display: none; }
  .step-connector { width: 32px; }

  .feature-grid {
    grid-template-columns: 1fr;
  }

  .flow-cards {
    flex-direction: column; gap: 12px;
  }

  .flow-arrow {
    transform: rotate(90deg);
    padding: 4px 0;
  }

  .navbar { padding: 16px; }

  .footer-dot { display: none; }
  .footer-inner { display: flex; flex-direction: column; gap: 4px; }

  .success-address { font-size: 16px; padding: 12px 20px; }
}