/* =========================================================
 *  雅思4分英语助手 —— 样式
 * ========================================================= */

:root {
  --primary: #4f46e5;
  --primary-dark: #4338ca;
  --green: #10b981;
  --red: #ef4444;
  --bg: #f4f5fb;
  --card: #ffffff;
  --text: #1f2430;
  --muted: #6b7280;
  --border: #e5e7eb;
  --radius: 14px;
  --shadow: 0 1px 3px rgba(16,24,40,.06), 0 6px 16px rgba(16,24,40,.06);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
}

/* ---------- 头部 ---------- */
.header {
  background: linear-gradient(135deg, #4f46e5, #7c3aed);
  color: #fff;
  padding: 22px 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
}
.brand { display: flex; align-items: center; gap: 14px; }
.logo {
  font-size: 32px;
  width: 56px; height: 56px;
  background: rgba(255,255,255,.18);
  display: grid; place-items: center;
  border-radius: 16px;
}
.brand h1 { font-size: 22px; font-weight: 700; }
.brand p { font-size: 13px; opacity: .85; }
.header-stats { display: flex; gap: 10px; flex-wrap: wrap; }
.stat-pill {
  background: rgba(255,255,255,.15);
  border: 1px solid rgba(255,255,255,.25);
  padding: 7px 14px; border-radius: 999px; font-size: 13px;
}
.stat-pill b { font-weight: 700; }

/* ---------- 导航 ---------- */
.nav {
  background: var(--card);
  border-bottom: 1px solid var(--border);
  display: flex; gap: 4px;
  padding: 10px 20px;
  overflow-x: auto;
  position: sticky; top: 0; z-index: 20;
}
.tab {
  border: none; background: transparent;
  padding: 10px 18px; border-radius: 10px;
  font-size: 15px; cursor: pointer; color: var(--muted);
  white-space: nowrap; transition: all .15s;
}
.tab:hover { background: #eef0f7; }
.tab.active { background: var(--primary); color: #fff; font-weight: 600; }

/* ---------- 主体 ---------- */
.main { max-width: 1080px; margin: 0 auto; padding: 24px 20px 60px; }
.module { display: none; }
.module.active { display: block; }

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 22px;
}
.section-title { font-size: 20px; margin-bottom: 4px; }
.section-desc { color: var(--muted); font-size: 14px; margin-bottom: 18px; }
.hidden { display: none !important; }
.muted { color: var(--muted); }

/* ---------- 首页 ---------- */
.hero {
  background: linear-gradient(135deg, #4f46e5, #7c3aed);
  color: #fff;
  border-radius: var(--radius);
  padding: 28px;
  margin-bottom: 20px;
}
.hero h2 { font-size: 24px; margin-bottom: 8px; }
.hero p { opacity: .92; font-size: 15px; max-width: 680px; }

.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 14px;
  margin-bottom: 22px;
}
.stat-card {
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow); padding: 18px;
}
.stat-card .num { font-size: 28px; font-weight: 800; color: var(--primary); }
.stat-card .label { font-size: 13px; color: var(--muted); }

.quick-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 14px;
  margin-bottom: 22px;
}
.quick-card {
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow);
  padding: 20px; cursor: pointer; transition: transform .15s, box-shadow .15s;
}
.quick-card:hover { transform: translateY(-3px); box-shadow: 0 10px 24px rgba(16,24,40,.12); }
.quick-card .icon { font-size: 28px; }
.quick-card h3 { font-size: 16px; margin: 8px 0 4px; }
.quick-card p { font-size: 13px; color: var(--muted); }

.today-plan { margin-top: 8px; }
.today-plan h3 { margin-bottom: 10px; }
.today-plan li { list-style: none; padding: 8px 0; font-size: 14px; }

/* ---------- 单词 ---------- */
.topic-chips { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 20px; }
.chip {
  border: 1px solid var(--border); background: var(--card);
  padding: 8px 14px; border-radius: 999px; cursor: pointer; font-size: 14px;
  transition: all .15s;
}
.chip:hover { border-color: var(--primary); color: var(--primary); }
.chip.active { background: var(--primary); color: #fff; border-color: var(--primary); font-weight: 600; }

.vocab-layout { display: grid; grid-template-columns: 1fr 320px; gap: 18px; }
@media (max-width: 820px) { .vocab-layout { grid-template-columns: 1fr; } }

.flashcard { perspective: 1000px; height: 300px; cursor: pointer; }
.flashcard-inner {
  position: relative; width: 100%; height: 100%;
  transition: transform .5s; transform-style: preserve-3d;
}
.flashcard.flipped .flashcard-inner { transform: rotateY(180deg); }
.face {
  position: absolute; inset: 0; backface-visibility: hidden;
  border-radius: var(--radius);
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  text-align: center; padding: 24px; border: 1px solid var(--border); box-shadow: var(--shadow);
}
.face.front { background: var(--card); }
.face.back { background: linear-gradient(135deg, #eef2ff, #faf5ff); transform: rotateY(180deg); }
.face .word { font-size: 36px; font-weight: 800; color: var(--primary); }
.face .pos { color: var(--muted); margin-top: 6px; font-size: 14px; }
.face .hint { color: var(--muted); font-size: 13px; margin-top: 16px; }
.face .meaning { font-size: 24px; font-weight: 700; }
.face .example { font-size: 16px; font-style: italic; color: #4338ca; margin: 10px 0 4px; }
.face .example-zh { font-size: 14px; color: var(--muted); }

.word-controls { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 16px; }
.progress-bar { height: 8px; background: var(--border); border-radius: 999px; overflow: hidden; margin-top: 16px; }
.progress-bar > span { display: block; height: 100%; background: var(--primary); transition: width .3s; }
.progress-text { font-size: 12px; color: var(--muted); margin-top: 4px; }

.word-side h3 { font-size: 15px; margin-bottom: 12px; }
.word-list { max-height: 340px; overflow-y: auto; }
.wl-item {
  display: flex; justify-content: space-between; align-items: center;
  padding: 8px 10px; border-radius: 8px; cursor: pointer; font-size: 14px;
}
.wl-item:hover { background: #f1f3f9; }
.wl-item.current { background: #eef2ff; color: var(--primary); font-weight: 600; }
.wl-dot.known { color: var(--green); font-weight: 700; }

/* ---------- 按钮 ---------- */
.btn {
  border: none; border-radius: 10px; padding: 10px 18px;
  font-size: 14px; cursor: pointer; font-weight: 600; transition: all .15s;
}
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); }
.btn-ghost { background: #fff; color: var(--text); border: 1px solid var(--border); }
.btn-ghost:hover { border-color: var(--primary); color: var(--primary); }
.btn-green { background: var(--green); color: #fff; }
.btn-red { background: #fff; color: var(--red); border: 1px solid #fecaca; }
.btn-sm { padding: 6px 12px; font-size: 13px; }

/* ---------- 测验 ---------- */
.quiz-box { margin-top: 18px; }
.tag {
  display: inline-block; padding: 4px 12px; border-radius: 999px;
  background: #eef2ff; color: var(--primary); font-size: 13px; font-weight: 600;
}
.q-word { font-size: 30px; font-weight: 800; color: var(--primary); margin-bottom: 16px; }
.quiz-options { display: grid; gap: 10px; }
.option {
  border: 1px solid var(--border); border-radius: 10px; padding: 12px 16px;
  cursor: pointer; font-size: 15px; background: #fff; transition: all .12s;
}
.option:hover { border-color: var(--primary); }
.option.correct { background: #ecfdf5; border-color: var(--green); color: #047857; }
.option.wrong { background: #fef2f2; border-color: var(--red); color: #b91c1c; }
.quiz-result { text-align: center; padding: 30px 0; }
.quiz-result .big { font-size: 44px; font-weight: 800; color: var(--primary); }

/* ---------- 听力 / 阅读 ---------- */
.lesson-list { display: grid; gap: 12px; }
.lesson-card {
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow); padding: 18px;
  cursor: pointer; display: flex; justify-content: space-between; align-items: center;
  transition: border-color .15s;
}
.lesson-card:hover { border-color: var(--primary); }
.done-badge { color: var(--green); font-weight: 600; font-size: 13px; }

.script-box {
  background: #f8fafc; border: 1px dashed var(--border);
  border-radius: 10px; padding: 16px; font-size: 15px; line-height: 1.9; margin-bottom: 16px;
}
.passage { font-size: 16px; line-height: 1.9; color: #2b303b; }
.question { margin-top: 16px; }
.q-text { font-weight: 600; margin-bottom: 8px; }
.q-options { display: grid; gap: 8px; }

/* ---------- 写作 / 口语 ---------- */
.prompt-box {
  background: #f8fafc; border-left: 4px solid var(--primary);
  padding: 14px 16px; border-radius: 8px; margin-bottom: 16px; font-size: 15px;
}
.practice {
  width: 100%; min-height: 160px; border: 1px solid var(--border); border-radius: 10px;
  padding: 14px; font-size: 15px; font-family: inherit; resize: vertical; line-height: 1.8;
}
.practice:focus { outline: 2px solid var(--primary); border-color: transparent; }
.word-count { font-size: 13px; color: var(--muted); text-align: right; margin-top: 6px; }
.model-answer {
  background: #f0fdf4; border: 1px solid #bbf7d0; border-radius: 10px;
  padding: 16px; line-height: 1.9; white-space: pre-wrap;
}
.phrase-list { padding-left: 20px; }
.phrase-list li { margin: 6px 0; }
.listen-result {
  margin-top: 12px; padding: 12px 14px; border-radius: 10px;
  background: #eef2ff; font-size: 14px;
}

/* ---------- 页脚 ---------- */
.footer {
  text-align: center; padding: 18px 20px; color: var(--muted); font-size: 13px;
  border-top: 1px solid var(--border); background: var(--card);
}