/* ========== متغيّرات الثيم ========== */
:root {
  --clr-bg: #f4f7fa;
  --clr-card: #ffffff;
  --clr-primary: #3949ab;
  --clr-primary-hover: #303f9f;
  --clr-text: #2c3e50;
  --clr-subtext: #666;
  --clr-error-bg: #ffefef;
  --radius: 12px;
  --transition: 0.25s ease;
  --shadow-light: 0 4px 14px rgba(0,0,0,0.05);
  --shadow-hover: 0 6px 18px rgba(0,0,0,0.1);
}

/* ========== إعدادات عامة ========== */
* {
  box-sizing: border-box;
}
body {
  font-family: 'Tajawal', sans-serif;
  background-color: var(--clr-bg);
  color: var(--clr-text);
  margin: 0;
  padding: 0;
  direction: rtl;
  text-align: center;
}
.container {
  max-width: 400px;
  margin: 0 auto;
  padding: 2rem 1rem;
}

/* ========== الرأس ========== */
header img {
  max-width: 100px;
  margin-bottom: 0.5rem;
  transition: transform var(--transition);
}
header img:hover {
  transform: scale(1.1);
}
header h1 {
  font-size: 1.8rem;
  margin: 0.2rem 0;
  color: var(--clr-primary);
}
.subtitle {
  font-size: 1rem;
  color: var(--clr-subtext);
  margin-bottom: 1.5rem;
}

/* ========== الآلة الحاسبة ========== */
.calculator {
  background-color: var(--clr-card);
  padding: 1.5rem;
  border-radius: var(--radius);
  box-shadow: var(--shadow-light);
  transition: box-shadow var(--transition);
}
.calculator:hover {
  box-shadow: var(--shadow-hover);
}

/* شاشة العرض */
#display {
  width: 100%;
  height: 50px;
  font-size: 1.4rem;
  padding: 0.4rem 0.8rem;
  margin-bottom: 1rem;
  border: 1px solid #ccc;
  border-radius: var(--radius);
  background-color: #eef1f5;
  text-align: right;
}

/* شبكة الأزرار */
.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.6rem;
}

/* أزرار الأرقام والعمليات */
button {
  padding: 0.8rem;
  font-size: 1.1rem;
  border: none;
  border-radius: var(--radius);
  background-color: var(--clr-primary);
  color: #fff;
  cursor: pointer;
  transition: 
    background-color var(--transition),
    transform var(--transition),
    box-shadow var(--transition);
  box-shadow: 0 2px 6px rgba(0,0,0,0.1);
}
button:hover {
  background-color: var(--clr-primary-hover);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}
button:active {
  transform: translateY(0);
  box-shadow: 0 1px 4px rgba(0,0,0,0.1);
}

/* ========== التذييل ========== */
footer {
  margin-top: 2rem;
  font-size: 0.9rem;
  color: var(--clr-subtext);
}
footer a {
  color: var(--clr-primary);
  text-decoration: none;
  font-weight: bold;
  transition: color var(--transition);
}
footer a:hover {
  color: var(--clr-primary-hover);
}

/* ========== استجابة الموبايل ========== */
@media (max-width: 480px) {
  header h1 { font-size: 1.6rem; }
  .subtitle { font-size: 0.9rem; }
  #display { font-size: 1.2rem; height: 45px; }
  button { font-size: 1rem; padding: 0.7rem; }
}